#⚛️┃physics | Official Unity Discord | Page 38

lapis plaza May 16, 2019, 2:52 PM

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well, you can technically move physics bodies or some query purpose only duplicates temporarily in interpolated places for queries on Update in some cases

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but yeah, I wouldn't expect engine to do that out of the box as it's kinda hacky

ocean horizon May 16, 2019, 3:18 PM

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well, you can technically move physics bodies or some query purpose only duplicates temporarily in interpolated places for queries on Update in some cases
I don't follow.

lapis plaza May 16, 2019, 3:32 PM

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I mean, you can temporarily have some colliders you trace against on regular Update that use the interpolated transform

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to match the gameplay visuals

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there was some specific use case for this but I haven't really been in situation where I'd really need it myself

ocean horizon May 16, 2019, 3:38 PM

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I still don't follow what you mean and why you're tell me that based upon what I said but it don't matter. 😃

lapis plaza May 16, 2019, 3:40 PM

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I mean, if player queries things on screen, assuming they are where they render and you use interpolation, your traces etc will not always hit where the player thinks they would

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same with extrapolation too

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imagine a 90Hz VR game with default 50Hz physics update rate for example (I wouldn't make VR game with lower physics update rate tho)

ocean horizon May 16, 2019, 3:42 PM

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Yes, that's really just stating what I said that transform != physics-pose-state when interpolation/extrapolation is used. Exactly.

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If that's required then manually stepping per-frame can be done assuming that's acceptable.

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Most of the time however, the difference is trivial unless you've got fast moving objects.

lapis plaza May 16, 2019, 3:44 PM

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sure, agree on that 😃

ocean horizon May 16, 2019, 3:44 PM

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The biggest issues I see in projects are when devs use transform.pos to base rb movement on

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when it should obvs be rigidbody.pos when inter/extrapolation is used.

tropic hamlet May 16, 2019, 5:03 PM

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Does anyone actually use extrapolate really? I mean, has it ever been useful?

ocean horizon May 16, 2019, 5:06 PM

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You'd need to do a poll. 😃

tropic hamlet May 16, 2019, 5:08 PM

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I'd need to do a poll but you can just leaf through editor analytics :D

lapis plaza May 16, 2019, 5:10 PM

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It has it's places

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Interpolation will always lag one frame behind

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Extrapolation tries to show the thing where it should be at that given time

ocean horizon May 16, 2019, 5:12 PM

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Note that Interpolation can be an arbitrary number of frames behind the actual physics pose.

lapis plaza May 16, 2019, 5:13 PM

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I mean rendered frame now, as interpolation technically shows the position in past

ocean horizon May 16, 2019, 5:14 PM

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Yes, that's what I mean too.

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If there were 10 rendered frames between each fixed-update then each one would be "behind" the actual physics pose.

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I'd need to do a poll but you can just leaf through editor analytics
There are no detailed analytics for that kind of stuff AFAIK

tropic hamlet May 16, 2019, 5:15 PM

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a shame I think

ocean horizon May 16, 2019, 5:16 PM

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Maybe so. I think a lot of internal devs went crazy when analytics came out but then budgets on what we can/should be looking at came in.

lapis plaza May 16, 2019, 5:17 PM

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ah, I guess you can view it that way too

ocean horizon May 16, 2019, 5:17 PM

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Maybe we break stuff occasionally just to see if it's being used.

tropic hamlet May 16, 2019, 5:17 PM

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was hilarious when sales started looking at what people were doing in editor and pushing emails to people offering advice with it, freaked a whole lot of people out :)

ocean horizon May 16, 2019, 5:17 PM

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That is (of course) a joke. 😉

lapis plaza May 16, 2019, 5:17 PM

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I always draw these on paper when I do interpolation math myself

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the example on https://gafferongames.com/game-physics/fix-your-timestep isn't correct either

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(well, that site seem to be down now but most physics programmers probably know what was there)

ocean horizon May 16, 2019, 5:21 PM

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In Unity it's quite simple. Each fixed-update (actually when the physics simulate is called) we copy the current pose and make it the previous pose then run the sim which means of course that we have a from->to (current) pose to work with. Then during update (per-frame) we simply set the pose to be between from->to according to the time-elapsed. Then a new fixed-update happens at some time interval in the future and it starts all over again.

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Unfortunately, this is based upon the player-loop that is beyond our control so has a few issues.

lapis plaza May 16, 2019, 5:22 PM

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yeah, I've done it like that too as it's simpler

ocean horizon May 16, 2019, 5:22 PM

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One is that fixed-update can be called multiple times back to back.

lapis plaza May 16, 2019, 5:23 PM

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technically you'd get more accurate results if you stored each fixedupdate transforms and lerped only between the two states that are closest to the point you want

ocean horizon May 16, 2019, 5:23 PM

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That's what we do unless I'm misunderstanding what "closest to the point you want" is.

lapis plaza May 16, 2019, 5:24 PM

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I understood that you lerp between previous runs state and current runs final physics states

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there could be x states in between, depending how many times physics ran there

ocean horizon May 16, 2019, 5:25 PM

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Yes, that's what I was trying to explain above with multiple steps

lapis plaza May 16, 2019, 5:25 PM

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and sometimes you don't run any steps at all

ocean horizon May 16, 2019, 5:25 PM

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and sometimes you don't run any steps at all
?

lapis plaza May 16, 2019, 5:26 PM

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depending on your framerate and how much time you got left from previous pass, you may not have enough time to run any fixedupdate on the game loop

ocean horizon May 16, 2019, 5:27 PM

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Well it isn't limited like that.

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None of this is realtime anyway, it's based upon game-time

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multiple fixed-updates are called to "catch-up" to game-time

lapis plaza May 16, 2019, 5:28 PM

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I think we talk about different things now 😃

ocean horizon May 16, 2019, 5:28 PM

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Maybe so. My point is to highlight how it's done in Unity.

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That multiple-fixed-update issue is stupid and tbh, could be sorted.

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Interpolation also shouldn't be something that is done by physics. It should be part of the transform system.

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This is likely how we'll see it in dots.

lapis plaza May 16, 2019, 5:30 PM

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I'd just wish they do the whole fixedupdate fully in dots

ocean horizon May 16, 2019, 5:31 PM

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The playerloop is exposed and more of that is coming.

lapis plaza May 16, 2019, 5:31 PM

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right now that part of the implementation is open

inner cloud May 18, 2019, 2:37 PM

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originaly i did this

rb.velocity = (rotor.forward * 40) * Time.fixedDeltaTime;
```which gave me de results i wanted but by setting the velocity it also meant that if i ran into a wall i would always keep the same velocity thus not resetting and making the player shoot out once it doesn't run into the wall

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So i figured that i'll do this instead

rb.velocity += (rotor.forward * 40) * Time.fixedDeltaTime;
``` but now my player is sliding like on ice because it keeps also the previous velocity and adding onto it

sly violet May 18, 2019, 3:28 PM

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If you want the physics to work, you must work with the physics instead of against it. The easiest way to maintain relatively constant velocity is to use AddForce with a decently high drag. This will keep you from going too fast, give you nice acceleration and deceleration curves, and respect walls and other colliders.

inner cloud May 18, 2019, 3:31 PM

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but with AddForce i will still slide because of the velocity right ?

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i would like sharp turns

sly violet May 18, 2019, 3:48 PM

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You can mitigate that by cranking the drag, but yes. A character controller might be what you need. Those operate by detecting colliders in front of them as they move.

inner cloud May 18, 2019, 3:49 PM

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Unfortunatly i need a full rotation for the player and the character controller can't rotate

tropic hamlet May 18, 2019, 3:51 PM

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@ocean horizon agreed with the transform thing, it's really not physics job to do anything except simulate the world in steps. the visuals aren't physical, and even cause people to write bad physics code because they're so confused about if they should use rb.position or transfom.position, and I've had to fix many people's code like that (for example rigidbody controllers)

inner cloud May 18, 2019, 3:52 PM

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i'll see if i can adjust the drag but i i think i am gonna have to do it from scratch

tropic hamlet May 18, 2019, 3:55 PM

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@inner cloud check https://docs.unity3d.com/Manual/ExecutionOrder.html when working with velocity to ensure your work enters the system at the right time

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The order is: fixedupdate (your code) -> unity's physics update -> callbacks (ontrigger etc)

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so usually you're reacting to things frame late

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and you need to bear in mind that your changes hit just before the simulation step and your changes are based on the previous simulation step

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this is not complex to work with just know that the velocity can change right after you set it

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sliding is something that could definately happen but maybe not why you think it's happening

inner cloud May 18, 2019, 4:00 PM

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Sorry but i don't understand the sliding is a normal behavior by doing CS rb.velocity += (rotor.forward * 40) * Time.fixedDeltaTime;
im just adding this velocity onto the last one

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right ?

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doing CS rb.velocity = (rotor.forward * 40) * Time.fixedDeltaTime;
was good because i was only modifying the velocity on a single axis but at the price of the "world awareness"

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like running into a wall makes my player stops because of the the physic calculation under the hood but as soon as it doesn't faceplant on the wall it shoots out at the velocity i set wich is high

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maybe i could add a flag that says "if im running into a wall eg. rigidbody.velocity.magnitude <= 0, decelerate or return

sly violet May 18, 2019, 4:19 PM

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Just remember if you crank the drag you have to crank the force, too, but you can get almost arbitrarily small sliding and frankly I think that a little bit makes it look more realistic and feel better.

inner cloud May 18, 2019, 4:21 PM

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what about the angular drag isn't this a drag for the rotation ?

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it look like something i could use

sly violet May 18, 2019, 4:23 PM

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Yeah, angular drag is for angular momentum and is "opposed" by torque (AddTorque).

inner cloud May 18, 2019, 4:24 PM

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Ok i'll give it a try then, at least until i find a way to not use a rigidbody

strong plaza May 19, 2019, 1:49 PM

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you could draw the line of the raycast, for example in OnDrawGizmos to check if the ray goes into the right direction, for example: have you made sure that the z+ direction of the aim transform points forward?

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this runs on a headless instance of unity?

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I mean you could debug in text but,
okay
next is that raycasts have an interaction parameter: include triggers too or only colliders, but I guess the enemy has a regular collider so it should be fine,
next is the collision mask, if you have certain layers, make sure this is covered (well not really an issue either I suppose, because if you don't provide a layermask, it should check against all layers),
what could also be is that you hit something before the ray even hits the enemy

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maybe it is hitting something that is on your character then

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there is raycastall too

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or you could put enemies on a separate layer

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raycastall will report all hits along the passed ray

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with the distance

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you haven't worked with layers?

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they are used to make physic queries more efficient

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or to instruct cameras to only render specific layers

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called culling mask

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ah okay

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that is really all the input I can give I think

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you could try, or you define a separate layermask for the raycast and make sure that the objects on your player and environment are not on it

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maybe you can just go with raycastall

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a 500m ray could be a little expensive for that though, depending on how many colliders you have in the scene

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maybe take a look into a documentation

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you get an array of hits

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you iterate over it and check if one is the enemy

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but that also means that if there is an obstacle between the enemy and you, you still have the enemy

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so you could check the distances between your player and the hit point of the hit

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if you want to make sure

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btw, the current approach will only ever work for 1 enemy

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you have an equality comparison with Enemy.NativePlayer

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maybe you can just give the special enemies a specific component and query for that

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or something

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or hold them in an array

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seems complicated

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well

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enemy can only ever be one person?

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okay, then it should work like any of the approaches above I think

strong plaza May 19, 2019, 2:27 PM

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you could try to use more console outputs at places you expect to be executed

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yeah, that is not fancy, but if it works for now, you can probably change it later,
I don't really get where the problem is to compare the direct references, but 🤷

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if you instead of comparing the positions you compare the transform reference?

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odd, maybe the collider that is hit is just a child object of the player transform

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could be a lot of things, don't really know

sly violet May 19, 2019, 3:44 PM

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FixedUpdate should execute 20+ times per second so long as the fixed time step is 0.05 or less. The default value is 0.02, which is 50 times per second.

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I would be worried about calling serverSendMessage every fixed update.

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Raycasts can get expensive if you use a lot of them.

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I would be worried about calling serverSendMessage every fixed update.

lapis plaza May 19, 2019, 4:23 PM

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Why would one send any networking related on fixedupdate?

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You can have multiple fixedupdates executed one after another, there is no real delay between them in real time so you could just sent the state from last one after fixedupdates are done

zinc furnace May 21, 2019, 8:14 AM

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Has anyone here created their own physics system from scratch? @me if you reply :)

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Im trying to figure out how i want to model constraints. Should i make drag consistent, unrelated to weight, in regards to movement and rotation? In my case friction doesnt much matter as its in space, and all movement is through empty void. So, drag coefficients based on speed of movement only, and the application of forces calculates the final speed change considering the weight. Sound good?

shell isle May 21, 2019, 10:56 AM

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using com.unity.physics, Am i able to apply acceleration by using ApplyLinearImpulse, since it requires the entity mass (i assume for the acceleration formula)?
Ps.: i'm using pure ECS.

inner cloud May 21, 2019, 7:35 PM

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can i restrict rigidbody velocity to a axis ?

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like a car who will go down a hill if facing downward but doing nothing if perpendicular to it

hollow echo May 22, 2019, 2:04 AM

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You can use functions like Vector3.Project to find the component of the slope that you want to apply to your vehicle

desert pecan May 22, 2019, 2:09 AM

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any idea how I could make an arrow with a 2d raycast to check for collision instead of OnTriggerEnter2D

lapis plaza May 22, 2019, 6:59 AM

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@stuck bay that's a seriously old entities you have there

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blob assets don't exist on it

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physics package wants preview 30

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you don't have to add all these manually on your manifest tho

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just add the things you want to use and they will sort out the dependencies

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yeah but they are not the latest

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if you look at your package manager, it will show up arrow next to entities etc

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by installing them like that is manually messing up the dependencies

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just open the manifest.json manually and swap the lines you pasted here to this:```json
"com.unity.physics": "0.0.2-preview.1",
"com.unity.entities": "0.0.12-preview.30",

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preview 31 could work too, preview.32 does have issues with Unity Physics package (Unity is working on physics package upgrade)

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yeah, you didn't list you used hybrid

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😃

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oh right

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unity physics wants it

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I dunno why

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probably because of the conversion tools in it etc

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you have to put one extra package there

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I think json "com.unity.rendering.hybrid": "0.0.1-preview.10", is compatible with that entities version

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yay 😃

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normally I'd advice to use the latest versions but like mentioned, there are some issues with entities.preview.32 right now

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p31 could be fine too but p30 is what definitely works with the current physics package

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as for the package manager, it tends to want to install some ancient versions first

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I don't know why

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you can use the drop down menu per package to pick the newer versions before you even install it

inner cloud May 22, 2019, 7:32 AM

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@hollow echo I dont get it i dont want to align the rotation of the car to the normals of a surface, i want to kind of restrict the rigidbody velocity to a axis
lets say that i have made a car with rigidbody in mind, if i drop my car on a hill it should go down the hill even if i dont break or accelerate like a real car and if i turn while going down still without the engine on and without breaks i should go toward the direction i am stearing with the speed i have built up by going down the hill

hollow echo May 22, 2019, 7:38 AM

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I'm pretty sure wheel colliders would handle all this, but I don't do vehicles, but when I've worked with characters along similar lines (redirecting velocity) you just need to find the slope vector and the direction of travel (the steering vector) and project one onto the other, which gives you the amount the slope vector is contributing in relation to the steering vector. Then you use that to calculate the force it should be adding to the vehicle.
You can also find the contribution the current velocity has on the vector perpendicular to the steering vector, and add force to counteract that (ie. the traction force), more complex models would figure out the amount of down-force based on the slope or how much downward velocity the vehicle also has.

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Basically it's all a bunch of messing around with cross products and projections

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But I can't really help beyond this, perhaps someone else would have the maths on hand, or a nice tutorial, I'd just be doing the work for you 😛

inner cloud May 22, 2019, 7:40 AM

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Its ok i kind of understand how i should do this thanks 😄

pseudo flame May 22, 2019, 10:23 AM

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Hello people. I have a question. What do I do to make enemy units rigidbody kinematic towards player units rigidbody but not kinematic towards other enemy units rigidbody?

desert pecan May 22, 2019, 11:45 AM

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@pseudo flame layers

pseudo flame May 22, 2019, 11:46 AM

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@desert pecan I did split them into two separate layers, but how do I make one layer kinematic towards the other?

desert pecan May 22, 2019, 11:47 AM

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go into your project settings

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and change the layer matrix

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so enemy doesn't collide with enemy

pseudo flame May 22, 2019, 11:48 AM

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I want them to collide. I do not want one layer to affect the other

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Means enemy should push away player, but NOT vice versa

desert pecan May 22, 2019, 11:49 AM

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so everything collides but the player can't push the enemy away?

pseudo flame May 22, 2019, 11:49 AM

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Yeah

desert pecan May 22, 2019, 11:50 AM

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how are the enemies pushing the player

pseudo flame May 22, 2019, 11:51 AM

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Both player and enemies are moved by code via rigidbody.MovePosition

desert pecan May 22, 2019, 11:53 AM

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check if the player is colliding with the enemy, if it does stop the movement

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you can do this with raycasting a line in the direction you're walking

pseudo flame May 22, 2019, 11:54 AM

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The issue here is I have a little swarm of player units. Even 30 units raycasting each update on mobile device would be a little bit of FPS trouble

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And not simply raycasting but also trying to find out how close can they get to the enemy they're raycasting against as well

desert pecan May 22, 2019, 11:56 AM

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a simple raycast wouldn't be too much on the performance?

pseudo flame May 22, 2019, 11:56 AM

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I'll give it a try. Thanks @desert pecan

desert pecan May 22, 2019, 11:57 AM

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np

sly violet May 22, 2019, 2:31 PM

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@pseudo flame : You can do exactly what you're asking by having the Players and Enemies on separate Layers, and then making a kinematic Rigidbody for each Enemy that follows its movement on the Players Layer.

pseudo flame May 22, 2019, 2:32 PM

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@sly violet In this case two adjacent kinematic enemies can move through each other

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kinematic is not interacting with kinematic in any way

sly violet May 22, 2019, 2:43 PM

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No, there's an Enemy Layer where they interact with each other normally. The kinematic bodies on the Player layer don't interact with that, they're just there to push the Player.

pseudo flame May 22, 2019, 2:43 PM

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Aaaaaah

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But that means that I have to join them with a fixed joint

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Good point. Thanks @sly violet

sly violet May 22, 2019, 3:00 PM

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Don't use a joint! You don't want the kinematic "ghost" bodies pushing the regular physics bodies. Just have the kinematic bodies follow in code.

pseudo flame May 22, 2019, 3:10 PM

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@sly violet That's exactly what I want them to do

sly violet May 22, 2019, 3:42 PM

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You want the kinematic body, which by nature does not move under its own power, to utterly prevent the Fixed-Joint-Connected Enemy bodies from moving?

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Clearly I misunderstood your proposition. 😉

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Look, maybe you should just make the Enemies have a much larger mass than the Players. You don't seem to be grasping the Layers stuff.

inner cloud May 22, 2019, 7:32 PM

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I have this for a car to be able to gain speed while going down a hill and also by accelerating

rb.velocity = Vector3.Project(rb.velocity, wheel.forward) * Force * Time.fixedDeltaTime;  ```
but when i use this code it teleports me out of the reality because it has to be normalized

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but i dont know how i could add the Force var the axis velocity

sly violet May 22, 2019, 7:46 PM

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I think you can just take out the Force and delta time parameters and get something sort of close.

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rb.velocity = Vector3.Project(rb.velocity, wheel.forward);```
That should extract the forward velocity from the total velocity and apply it back to the current velocity.

inner cloud May 22, 2019, 7:48 PM

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Yes i know this works but i also want to add force to this

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the Force would be the acceleration but i dont know to add this float to the this projected velocity

sly violet May 22, 2019, 7:55 PM

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Maybe just use AddForce. Can't you find an asset that'll do what you need without spending days puttering around with the physics?

inner cloud May 22, 2019, 7:57 PM

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Well no this would miss the point of trying to learn

sly violet May 22, 2019, 7:57 PM

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Okay. The reason your code didn't work is that you're multiplying the force instead of adding it.

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You were right that you need to have a normalized vector.

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I think you'll need to split that into two operations, because you need the projection twice.

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First, you get the projection as a Vector. This is your current velocity, in the forward (or backwards) direction.

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Then you get the normal of that Vector - which is just Vector3.normalized - and multiply that times your force and your delta time. This gives you your acceleration in the forward direction.

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Finally, you add those two vectors together to get your new velocity.

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Vector3 projection = Vector3.Project(rb.velocity, wheel.forward);
Vector3 acceleration = projection.normalized * Force * Time.deltaTime;
rb.velocity = projection + acceleration;```

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BTW, I used just "Time.deltaTime" because that's equivalent to Time.fixedDeltaTime inside FixedUpdate.

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This means code can be transported between Update and FixedUpdate without breaking. Not really important in this case, but a good practice in general.

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Hope that helps. Sorry I snarked earlier.

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Wait, that's dumb.

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projection.normalized is just wheel.forward.

inner cloud May 22, 2019, 8:03 PM

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Its ok i got used to it when i did network 😄

sly violet May 22, 2019, 8:03 PM

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Let me try that again.

inner cloud May 22, 2019, 8:03 PM

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well yeah wheel is the normalized axis

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but it seems to be working at first glance

sly violet May 22, 2019, 8:04 PM

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So all you need is:

rb.velocity = Vector3.Project(rb.velocity, wheel.forward) + (wheel.forward * Force * Time.deltaTime);```

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Yeah, it should work, it's equivalent, but "normalized" requires a square root and is relatively expensive, so no point in doing an extra one.

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Normalizing a vector is really just dividing it by its magnitude, giving it a magnitude of 1. And getting a magnitude takes a square root.

inner cloud May 22, 2019, 8:07 PM

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It seems to be working aswell thanks a lot ! 😃

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im just going through some walls but i think thats because i need to put the Time.fixedDeltaTime back

sly violet May 22, 2019, 8:09 PM

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I think any time you hard-set velocity you put yourself in danger of going through walls. I had hoped that since you were just using a projection with an acceleration, it wouldn't have that effect (because collisions can still push you back out), but I guess apparently not?

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Are you going through walls slowly, or skipping through them at high speed?

inner cloud May 22, 2019, 8:12 PM

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i had the Force set too high and i just got frozen stuck in the wall

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fully inside but at the start

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its ok though i'll remove the rigidbody at some point thats why i hard code the velocity so i dont have to change too much when i'll remove it

sly violet May 22, 2019, 8:15 PM

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BTW strictly speaking that's being used as an acceleration factor and not a force. If it was a force, it would need to be divided by mass to get the equivalent acceleration.

inner cloud May 22, 2019, 8:16 PM

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ahh ok thats why i kind of slowly accelerate

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It makes sense yeah

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should i divide the whole thing by the mass ?

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i tried it but it doesn't look like it changed much

sly violet May 22, 2019, 8:21 PM

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Well, if the mass is 1, it won't actually change anything... You can just play with the acceleration factor until it works about how you want.

gilded sparrow May 23, 2019, 8:56 AM

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I have a prefab with Collider and Rigidbody set to Collision Detection: Continuous
Clicking on another and back to this prefab, the Collision Detection switches back to Continuous Speculative.
Why is this happening?

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It only respects the change if it's set to Discrete or Continous Speculative. If changed to the other 2 options, it always reverts back to the Speculative, after selecting other object..

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K nvm, it doesnt work on kinematic i guess..

stuck bay May 23, 2019, 4:50 PM

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Im new and i have problem with my code

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I cant jump

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using System.Collections.Generic;
using UnityEngine;

public class Moving2D : MonoBehaviour
{
    public float moveSpeed;
    public float jumpHeight;
    public Rigidbody2D rb;
    public bool isGrounded;
    void Update()
    {

            Jump();

        if (Input.GetKey(KeyCode.D))
        {
            rb.velocity = new Vector2(moveSpeed, rb.velocity.y);
        }

        if (Input.GetKey(KeyCode.A))
        {
            rb.velocity = new Vector2(-moveSpeed, rb.velocity.y);
        }
    }

    void Jump()
    {
        if (Input.GetKeyDown(KeyCode.Space) && isGrounded)
        {
            rb.velocity = new Vector2(rb.velocity.x, jumpHeight);
            isGrounded = false;
        }
    }
    void OnCollisionStay()
    {
        isGrounded = true;
    }
}

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I tried 3 other codes for jump but all of theme didnt work at me

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So can anybody help me with that?

frigid pier May 23, 2019, 5:02 PM

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@stuck bay OnCollisionStay has to have a parameter to be recognized as a reserved method and be triggered https://docs.unity3d.com/ScriptReference/MonoBehaviour.OnCollisionStay.html

stuck bay May 23, 2019, 5:14 PM

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I think im too new becouse i copied this jump script from internet and i dont know whats wrong and what to do with this now even after help of others

frigid pier May 23, 2019, 5:18 PM

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Look up examples, make use of Debug.Log() to listen what its doing.

stuck bay May 23, 2019, 5:19 PM

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ok

quartz wyvern May 24, 2019, 6:56 AM

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say i have a RB of 1 unit mass and i want it to jump 4 units up . how do i know how many units my impulse force should be ?

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i put 4 but it only jumped 1 meter

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doesn't quite make much sense

sly violet May 24, 2019, 7:32 AM

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If you apply 4 impulse to mass of 1, you get a velocity of 4. That's not the same thing as the height you'll reach. Standard gravity is 9.8/s/s, which means that in a single second your velocity goes from 4 all the way to -5.8!

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For an actual answer based on real-world physics, maybe try something like this:
https://www.quora.com/How-do-I-find-max-height-when-only-given-an-initial-velocity

How to find max height when only given an initial velocity - Quora

This question can be solved in many different ways. Lets solve it by applying energy conservation principle. Let us assume “u “is the initial velocity. Let us also assume that Potential energy at the point of projection to be 0. Then.. Total energ...

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However, note that in-game physics will be a bit off from real-world physics, and any drag will make things extra wonky.

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...Experimenting may be more efficient.

quartz wyvern May 24, 2019, 8:46 AM

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I think I'll use animation for jump with physics on since I can't easily control how quickly to jump with the height of the jump from just forces

sly violet May 26, 2019, 3:39 AM

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Report a bug is the standard, though you might consider posting on the Unity forums in Physics, I know some of the devs frequent there, at least more than here. BTW, what's the problem? I avoid non-basic colliders whenever possible, but sometimes it just seems more efficient.

kindred aspen May 26, 2019, 6:13 AM

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I'm using springs for the wheels and locking them in place with basic code, but it seems to have somehow "disabled" the friction... Is there a different way to simply lock the wheels so they don't move (except for up and down ofc)?
I'm just using this as the code to keep the wheels in place in Update:

transform.localPosition = new Vector3(startCoords.x, startCoords.y, transform.localPosition.z);
transform.localRotation = Quaternion.Euler(transform.localRotation.eulerAngles.x, 0, 0);

📎 vid.gif

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ignore the horrible compression, its not a shader i swear

hollow echo May 26, 2019, 6:27 AM

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@kindred aspen Is there a reason to not use a wheel collider?
I'm fairly certain that by avoiding using forces you are avoiding using the physics system entirely

kindred aspen May 26, 2019, 6:28 AM

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I already know the answer - go look at the documentation - but I have no idea how they work... I guess I'll have to look into it?
have any tips for understanding it?

hollow echo May 26, 2019, 6:28 AM

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Nope, I don't do vehicle stuff, sorry!

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Doesn't seem too hard though, it even handles suspension for you

kindred aspen May 26, 2019, 6:29 AM

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alright - thanks anyways. I just needed something to look at.

sly violet May 27, 2019, 12:51 AM

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...One second you're evaluating the C# backing code, the next second you don't know anything about the timing basics? That's covered in the basic documentation.

lapis plaza May 27, 2019, 5:45 AM

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@stuck bay it's a side effect from entities simulation group change right before unity shipped unity physics package

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They'll sort it out eventually

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There is some fixed timestep spawner example on the repo, I dunno if that could be used to temp fix physics too

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There was also few line hack to fix the simulationgroup on p30 but I think it broke on p31+

muted rivet May 28, 2019, 10:15 AM

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Hello guys,
I'm trying to write a code for double jumping in a FPS game, but the problem is it does both jumps at the same time when I hit space. I tried to delay two jump with a "StartCoroutine" but it didn't work
This is the code:

        if (characterController.isGrounded)
        {
            jumpCount = 0;
        }
        if (jumpCount == 0 && Input.GetButton("Jump") && characterController.isGrounded)
        {
            verticalVelocity = jumpStrenght;
            jumpCount = 1;
            Debug.Log("Jumpcount: " + jumpCount);
        }
        if (jumpCount == 1 && Input.GetButton("Jump"))
        {
            verticalVelocity = jumpStrenght * 2;
            jumpCount = 2;
            Debug.Log("Jumpcount: " + jumpCount);
        }```

muted rivet May 28, 2019, 11:46 AM

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@stuck bay It worked, Thanks a lot

gilded sparrow May 28, 2019, 6:05 PM

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Hi guys. I'm trying to animate a sword, and when hit the target collider, it stops right on the OnTriggerEnter. Is this possible?
Or does it have to be collider (not trigger)?
I'm taking Time.time upon point of OnTriggerEnter, and use it with Time.time of start of the animation to "re set" the animator normalizedTime to it. The Enter triggers, but it's still passing through..

tardy tendon May 30, 2019, 8:51 PM

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Animation is seperate from physics

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you'd need to detect an on collision enter and interrupt the animation mid swing

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theoretically possible but if the animation is not at one of the keyframe points or at least close near one you might see some popping

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the point of an animation is to interpolate from keypoint a to keypoint b and if you stop it mid way.. it doesn't really retain that data for long

glacial tendon May 31, 2019, 12:19 AM

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(holding objects in VR) Is there a reason for a non kinematic rigidbody gameobject to lose all friction when MoveRotation is being applied? I'm trying to use MovePosition and MoveRotation with a non kinematic rigidbody so that the object will collide with static objects, but I cannot hold stacked objects because the object being held loses all friction.

sly violet May 31, 2019, 1:49 AM

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Move methods on non-kinematic rbs act as teleports rather than moves. Don't ask me why... That's why it acts frictionless.

glacial tendon May 31, 2019, 1:52 AM

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Thanks @sly violet . looks like ill be making my own solution then.

glacial tendon May 31, 2019, 3:27 AM

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I'm trying to hold the rotation of the rigidbody with force. For some reason it only rotates at a maximum speed, unlike with its position which does not 'lag' behind with the object. Is there something I'm missing to make sure it rotates with the grab rotation at any speed?

Quaternion grabbableRotation = rot * m_grabbedObjectRotOff;
        Quaternion rotDelta = grabbableRotation * Quaternion.Inverse(grabbedObject.transform.rotation);

        float angle;
        Vector3 axis;
        rotDelta.ToAngleAxis(out angle, out axis);
        Vector3 angleTarget = angle * axis;
        grabbedObject.rb.angularVelocity = Vector3.MoveTowards(grabbedObject.rb.angularVelocity, angleTarget, 10000f * Time.deltaTime);

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📎 rotationforce.gif

glacial tendon May 31, 2019, 6:24 AM

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I fixed my issue. Turns out I needed to change the rigidbody maxAngularVelocity .

lapis plaza May 31, 2019, 2:06 PM

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new PhysX 4.1 editor build: https://forum.unity.com/threads/physx-4-1-in-unity-experimental-builds.634960/page-2#post-4599571

Unity Forum

PhysX 4.1 in Unity - experimental builds

That said, why would some be unhappy.

Yeah, i don't want to sound too negative here. The new physics engine looks amazing! There is a bunch of stuff...

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now based on 2019.2

quartz wyvern Jun 3, 2019, 5:53 AM

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can rigidbodies inherit other rigidbodies

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eg if an object is moving on a platform thats also moving

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how do allow it to inherit the platform movement so any forces added to the rb will compound with the movement of the platform

gleaming shell Jun 3, 2019, 6:04 AM

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Making it a child should work if I understand your question correctly

quartz wyvern Jun 3, 2019, 6:05 AM

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maybe

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ill try it to find out

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its kinda annoying since i need to use transform rotations but there is no method for it in rigidbodies

gleaming shell Jun 3, 2019, 6:06 AM

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angularVelocity?

quartz wyvern Jun 3, 2019, 6:09 AM

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i need to use RotateAround()

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kinda tricky to work out with just angular velocity

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plus i need to control the motion more like an animation than actual physics - whilst still having collisions work

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so not sure the correct way to do it

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this is in Update so by the time it hits fixed update its not kinematic. would this still allow collisions to work correctly

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never mind my approach wont work anyway

gleaming shell Jun 3, 2019, 6:27 AM

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2d or 3d?

quartz wyvern Jun 3, 2019, 6:28 AM

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3d

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i cant make the object a child of the moving platform because it inherits the rotations and scales

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so i dunno how to get this to work

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this is the problem

📎 capture.gif

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it needs to go with it but not inherit rotation or scales

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suggestions ?

gusty sleet Jun 3, 2019, 6:32 AM

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Add the platform movement vector to your players movement vector

quartz wyvern Jun 3, 2019, 6:32 AM

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its a kinematic tho

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so wouldnt the platform have 0 velocity vector

gusty sleet Jun 3, 2019, 6:33 AM

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Why would it be kinematic if you're moving it..?

quartz wyvern Jun 3, 2019, 6:33 AM

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because im not using forces

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i need to use animations

gleaming shell Jun 3, 2019, 6:34 AM

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Your moving the platform using animation?

quartz wyvern Jun 3, 2019, 6:34 AM

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it follows a spline

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so its just lerping along the spline

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but still need collisions to work

gleaming shell Jun 3, 2019, 6:36 AM

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Maybe try adding the position difference from the base to the sphere in fixed update

quartz wyvern Jun 3, 2019, 6:37 AM

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this is the problem with setting it a child. it inherits the animation rotations and the like which i don't want

📎 capture.gif

gleaming shell Jun 3, 2019, 6:41 AM

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Well, I'm on my phone rn, but maybe you could set the spheres velocity to the distance between the last frames position and this frames position, divided by time, and multiplied by the direction the platform is going in

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Like the classic velocity=distance/time

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Though my worry is you won't get enough precision between frames

quartz wyvern Jun 3, 2019, 6:50 AM

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yeh

gleaming shell Jun 3, 2019, 6:51 AM

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Another solution, is having the scale and rotation on a separate sub-object, and then do just the movement on a parent object, and then attach the sphere to the parent

quartz wyvern Jun 3, 2019, 6:56 AM

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hm true

naive summit Jun 3, 2019, 12:40 PM

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I've seen this question asked a million times and every time I feel like the best answer is always to just add the offet from the platforms last position to that of the object sitting on it. @quartz wyvern

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Player on platform, begin tracking offsets.

Platform moved 1f Y over a frame, move player 1f Y

blissful shore Jun 3, 2019, 6:27 PM

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tracking offsets with the collision checks is how I do it

still quail Jun 4, 2019, 6:33 AM

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@quartz wyvern make the platform stationary, animate the whole world around it :)

brave niche Jun 4, 2019, 5:47 PM

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https://forum.unity.com/threads/rigidbody-doesnt-move-with-transform.688303/#post-4612075

Unity Forum

Rigidbody doesn't move with transform!!

I realized that sometimes my Rigidbody is not being moved along with my transform's position. This is with a trigger collider and kinematic rigidbody....

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anyone recognize this issue? I think the update to physX 3.4 stopped kinematic rigidbodies from following rigidbody parents.

drifting skiff Jun 4, 2019, 9:52 PM

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Hello i need some help im newbie on programing i want make a mobile game but i have a weird bug i don't believe this is a mistake i need some help

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📎 bandicam_2019-06-05_00-49-58-801.mp4

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Is it from rigidbody2D?

quartz wyvern Jun 5, 2019, 2:32 AM

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@naive summit late reply but isn't that the same as making it a child ?

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since child RBs inherit parent RBs ?

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ohh

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forgot about that

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so i need something like public Vector3 Delta => _lastFrame-_platformRB.position;
and
_objectRB.MovePosition(transform.position + platform.Delta); ?

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the Delta is on the platform class

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with _rb being the object on the platform

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ah ok same thing i probably should have used better variable names there

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shouldnt it be in fixed update ?

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hm i could increase physics tick rate

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my scenes ain't too complicated in reality

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well the platform is kinematic

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ill try it see how it goes

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the object on the platform is not kinematic since it uses forces

hoary crane Jun 5, 2019, 12:22 PM

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Omg it's Sir

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I am pretty sure that is the same sir from a server I used to be in

hoary crane Jun 5, 2019, 1:18 PM

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Is there a way to set force of a specific axes?

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Using Rigidbody 2D and the problem is, I add force to Y when they jump and use MovePosition for X axis but it completely screws the Y force

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I fixed it by creating a new vector2 for the velocity. At the start of the update I set x to 0 and y to the current y velocity

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If they press a key it sets the x velocity to either -2 or 2. when they jump it sets velocity to 5 and it works nicely now

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No longer overriding velocities when moving

quartz wyvern Jun 5, 2019, 7:29 PM

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apply the force in the desired direction

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that would then be the specific axis

gilded sparrow Jun 6, 2019, 4:50 AM

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Hi guys. Is it possible to have 2 colliders detect OnCollisionEnter, but ignore the resulting knockback (so i can do it in code instead) ?

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2 kinematics doesn't detect collision, it seems...

frigid pier Jun 6, 2019, 4:55 AM

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You probably need to exclude them from interaction in physics and use dedicated trigger collider to handle collision event instead.

gilded sparrow Jun 6, 2019, 4:57 AM

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Yeah that'd be the simpler way, but just wondering if i can use collider so i get the collision point + normals

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But anyways i just googled and found u can have non kinematic + freeze everything (position, rotation). So i'm trying that now

lapis plaza Jun 6, 2019, 5:39 AM

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@gilded sparrow yeah, you can't have two kinematics to create a collision

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you need something that's physics simulated for that

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as it's a thing fired by physics sim

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you can have to kinematics to use overlaps tho

gilded sparrow Jun 6, 2019, 5:40 AM

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FreezeAll-ing + non kinematic seems to work. But im not done trying it.
It's for networked and i wanna override the push value too

uncut glacier Jun 6, 2019, 11:56 AM

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why can I not select Continuous Dynamic on my rigidbody in 2019 while I'm perfectly capable of doing so in 2017? (I'm in the middle of porting to 2019)
It automatically swaps to Continouos Speculative

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but it makes my physic objects kinda "stick" to another. If I say move a platform from underneath another physic objects it follows the platform rather then fall downwards...

lapis plaza Jun 6, 2019, 12:55 PM

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@uncut glacier 2018.3 and newer use PhysX 3.4.2

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so it's probably related to that change

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Unity 5, 2017 and 2018.1 - 2018.2 used PhysX 3.3

uncut glacier Jun 6, 2019, 2:04 PM

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@lapis plaza Quick question, idk if you know but tagging you anyway :p
A static collider object (so an object with a collider and no rigidbody) is put into an "optimization" list for pure static colliders. Because you're basically never supposed to move these. however you can move them but if you do it's a performance hit. Is this performance hit still there and present if this pure static collider is turned into a trigger only? Will the object still be part of this "optimization" list and have a performance hit when it is moved?

lapis plaza Jun 6, 2019, 2:05 PM

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you shouldn't move static objects in general, regardless if it's a trigger or collider

uncut glacier Jun 6, 2019, 2:08 PM

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I have this "Touchreceiver" object on one of my gameobject that is basically used to trigger interaction. now it's static in relation to the object, but the object itself might move around in the world

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Should I add a kinematic rigidbody to this, locally, static collider?

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📎 unknown.png

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basiclaly this is the entire touchreceiver object...

lapis plaza Jun 6, 2019, 2:08 PM

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just add kinematic rb and don't mark it static

uncut glacier Jun 6, 2019, 2:10 PM

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so a trigger that moves in the world, wether it is static relative to it's parent, should always contain a kinematic rb ?

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so my setup (screenshot) will result in performance hits?

sly violet Jun 6, 2019, 3:57 PM

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"Static relative to its parent" is not really a thing for colliders, except insofar as that parent has a rigidbody and the child doesn't (in which case the collider is associated with that parent rigidbody).

royal briar Jun 6, 2019, 5:56 PM

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Does anyone know how to prevent two rigidbodies from pushing each other? (Enemy and player) I've tried looking for an answer for hours and haven't had any luck.

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https://gyazo.com/5d22823b24eca5495827fe9c887eddb0

Gyazo

▶ Play video

tropic hamlet Jun 6, 2019, 6:47 PM

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With code?

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On collision use Vector3.ProjectOnPlane to nullify the movement vector against a plane which is defined by subtracting one object against the other (similar to wall sliding).

In 2D this is significantly easier, just check the velocities and act accordingly. I suggest damping the x velocity rather than setting to 0 to prevent jitter

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If you want this to be automatic or have one be authoritative or never push player ever but stop you can consider making player kinematic or a way higher mass as a quick hack

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if its just enemies you don't want to push player then this is just OnCollisionEnter2D

royal briar Jun 6, 2019, 7:10 PM

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Alright, thanks @tropic hamlet

gilded sparrow Jun 6, 2019, 10:18 PM

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@uncut glacier
RB's shouldn't be able to be set to be COntinuous if they're kinematic.
Continuous speculative is a new thing that allows even kinematics to be set to a.. well, some kind of a Continuous

And @royal briar
My (most recent) case is a bit different than yours but, i thought the only way to "disregard" an RB from the reactiveness of physics is to set it kinematic.
But keeping it dynamic and FreezeAll constraints also works.

Although i'm not sure if the "push-ness" of another RB can be "nullified" this way too. The pushing RB has to be FreezeAll'd too.
And i'm assuming all the RB's are moved via code.

Really, the only reason why i chose to do this is because i want collider's OnCollisionX stuff but without it to actually result in physics movement.
The only real way are:

Use triggers. No collision whatsoever
Kinematics. But kinematics don't trigger OnCollision with each other
Keep at dynamic, then hippocoder's way of nullifying each OnCollision
The FreezeAll way, but as i only recently found this too, i'm not sure how many cases this can be applied to. I mainly use this to still get OnCollision's collision point, nullify the physics result, override the resulting collisions if needed, and have full control of those values to be sync'd in network

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And now my own question, hopefully someone knows something about PhysicsScene.Simulate(time)
I've been using it for my replay system and it works great, even for fraction times for slow-mo. But simulating in different speed, i'm noticing the collision values are different. Anyone know why and how to avoid it?

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I'm checking the value not in FixedUpdate (just reading in the docs that it's independent than Simulate time rate),
but in OnCollisionEnter.
Is it possible that making Simulate slow-mo calls the OnCollision earlier/later, diverging the physics story slightly differently?

quartz wyvern Jun 6, 2019, 10:39 PM

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ok so my RB has zero velocity (0,0,0) and zero angular velocity (0,0,0) yet is Sleeping is still false . is this because i am using MovePosition ?

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so confused how it defines what sleeping means here

sly violet Jun 7, 2019, 3:06 AM

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It certainly won't sleep if you're moving it.

quartz wyvern Jun 7, 2019, 3:40 AM

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@sly violet right so it also includes move position even if no forces are used

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i assumed it was relative to velocity and angular velocity

quartz wyvern Jun 7, 2019, 4:03 AM

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any one know how to smooth the movement out for displacements ? i have tried interpolate and extrapolate but they still jitter

📎 capture.gif

uncut glacier Jun 7, 2019, 9:00 AM

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https://gyazo.com/44364a7ff1805eadf8e8aac31ebf09af

Gyazo

▶ Play video

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manually moving a box by like 5 - 10 units it sometimes goes straight through the ball. How do I fix this??

gusty sleet Jun 7, 2019, 9:47 AM

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Don't move it manually

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You're teleporting the box

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(Even though it seems smooth)

uncut glacier Jun 7, 2019, 10:00 AM

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@gusty sleet It's a kinematic so it should move

gusty sleet Jun 7, 2019, 10:01 AM

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Nah, kinematic rigidbodies shouldn't move

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And moving in the scene view always teleports the object without caring about physics

uncut glacier Jun 7, 2019, 10:01 AM

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I have a hand (in VR) that I obviously move around and want to be physic enabled and I'm having the same issue as my little setup where my hand with kinematic rb's moves through objects sometimes

gusty sleet Jun 7, 2019, 10:01 AM

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You can probably improve it by using the interpolation setting on the rigidbody

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And using Rigidbody.MovePosition

uncut glacier Jun 7, 2019, 10:03 AM

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Rigidbody is attached to the hands so it automatically moves even wthout doing it in code (again, VR) and I also have an issue where sometimes my hand and objects kinda "stick" togheter

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I'm baffled by these physics and just trying to understand it. starting with my little test scene...

sly violet Jun 7, 2019, 1:24 PM

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That's unfortunate; means you don't know what kind of movement it's doing. Teleportation versus movement. You might just have to not attach it to the hands and instead place it in code. You'll need a kinematic rigidbody with continuous collision detection moved with Rigidbody.MovePosition.

uncut glacier Jun 7, 2019, 2:21 PM

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what is the differencce between rigidbodies not using gravity but one has kinematic enabled and one has kinematic disabled, how do they handle differently? I must admit I'm so confused with these physics >.<

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@sly violet you sound knowledgeable, you think you can shed some light?

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Also what happens if a child , who has a collider, is attached to a parent with it's own collider and rigidbody and you attach a rigidbody to that child? How will they behave? Would you even advice doing this? or no? I'm hella confused as you can tell about what happens with all these possible combinations...

sly violet Jun 7, 2019, 4:18 PM

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@uncut glacier : Kinematic objects don't move based on physics. You have to move them in code/animation/whatever. Consequently they aren't moved by forces, velocity, collisions, and so on.
If you give a child a Rigidbody, it becomes independent of its parent's Rigidbody, moving with its own Rigidbody/physics and not those of its parent. Note that in the Scene Editor it moves like a normal child instead, but in-game, not so much. Generally speaking I would avoid using parent-child relationships between Rigidbodies, but sometimes they're handy to organize prefabs.
If you need to connect two Rigidbodies with something that acts similar to a parent/child transform relationship, you typically use a FixedJoint (assuming you can't just have multiple colliders on the same Rigidbody to get the desired effect).

uncut glacier Jun 7, 2019, 8:32 PM

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That actually helped a ton! Thank you @sly violet

quartz wyvern Jun 8, 2019, 2:37 AM

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we can use MoveRotation for non kinematic objects right ?

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or will that cause issues

sly violet Jun 8, 2019, 3:16 AM

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Well, you can, but it can cause issues because it'll teleport instead of move.

quartz wyvern Jun 8, 2019, 3:26 AM

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its hard to figure it out from torques tho

sly violet Jun 8, 2019, 4:23 AM

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There's always trial and error. 😉

quartz wyvern Jun 8, 2019, 4:30 AM

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@sly violet if you're pushing a sphere, for it to spin do you use torque or just normal pushing force

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whats more correct by physX's standards

sly violet Jun 8, 2019, 4:31 AM

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If you want it to roll by friction on the ground, just give it a push.

gusty hazel Jun 8, 2019, 4:39 AM

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Hi I downloaded one of those asset packs where things are modular, I put it all together in the shape I wanted and thats all fine, I added mesh convex colliders to everything that needs collision, except I have these things that hold up a bar, and the holders are supposed to be fixed to the wall to hold the bar up, but when I added collision / rigidbodys now the holders just fall to the floor, any idea how I can make them become part of another asset basically? I have tried parenting the wall to the holder but it doesn't seem to have an affect

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Think I got it by freezing rotation / position as long as its under the parent

sly violet Jun 8, 2019, 4:42 AM

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The holders aren't static?
You could affix them with a FixedJoint.

gusty hazel Jun 8, 2019, 5:00 AM

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Is there a collider that will actually take the shape of something]

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I'm using Mesh convex but its laying a flat top on something that should be a crescent shape

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📎 unknown.png

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Shouldn't have that top to it

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so that something cylindrical can recede in it

gusty hazel Jun 8, 2019, 6:00 AM

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Any idea why my object might be falling through terrain, it is spawned above it, it has a mesh collider with convex checked, it has a rigidbody, mass of 2, gravity checked, collision detection discrete

quartz wyvern Jun 8, 2019, 6:08 AM

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@gusty hazel don't make it convex

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or use lots of smaller convex shapes to make the overall shape

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possibly lots of box colliders

gusty hazel Jun 8, 2019, 6:10 AM

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it is a bunch of smalls just not sure why it falls through floor

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Seems like it only falls through terrain when an external force acts on it, if i bump it in game, or try to move it in the scene when the game is running thats when it falls, but it will spawn and stay in place just fine

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even with just a box collider still falls through the earth

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Ok narrowed it down to being caused by the RigidBody component

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the collider alone works fine

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But rigidbody is causing it to act weirdf

inner cloud Jun 8, 2019, 8:11 AM

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Why are these grenades going through the floor but only some times ?

📎 new1.gif

#

The rigidbody is set to continous speculative and the colider to convex so what is wrong ?

📎 ccccc.png

mystic pawn Jun 8, 2019, 4:07 PM

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Why aren't you using a capsule collider? It'll be way more efficient.

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The physics guidelines I remember are mesh colliders should be used for large static objects and primitives (box, sphere, capsule) should be used on rigid body objects.

quartz wyvern Jun 8, 2019, 5:54 PM

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@inner cloud why such a complex collider shape lol

inner cloud Jun 8, 2019, 5:56 PM

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i didn't do it Unity did it but yeah i went back on a a primitive colider anyway

chilly crag Jun 9, 2019, 6:51 AM

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I have a bike model (not made by me) and when i add torque to the wheel the tyre comes out of the position and then moves ahead due to torque and friction....
And the bike remains there
How do i deal with this?
How can joint tyres with the bike
So that when i rotate tyre the bike would move ahead....

chilly crag Jun 9, 2019, 7:18 AM

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????

uncut glacier Jun 11, 2019, 9:43 AM

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https://gyazo.com/70cdac5fe339ad7f927dac174306995e

Gyazo

▶ Play video

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Both view windows use the same objects, same drag, same rigidbody settings, same script, same everything, the only difference is left is 2019.1 and right is 2017.1
I know the physics has changed between these 2 versions but what exactly might be causing the huge difference in reactiveness (right seems to have more drag than left (both set to 5))

lapis plaza Jun 11, 2019, 9:46 AM

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@uncut glacier hard to tell from that gif but visually it looks like the drag is exactly same on that

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what looks different is the part with collision response instead

uncut glacier Jun 11, 2019, 9:47 AM

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yea that's what I meant. why the left one get shot off into oblivion while right is nudged upwards ever so slightly

lapis plaza Jun 11, 2019, 9:47 AM

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I'd check the collision settings

uncut glacier Jun 11, 2019, 9:48 AM

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both left and right are Interpolate: None and Collision Detection: Discrete

lapis plaza Jun 11, 2019, 9:48 AM

#

also is that the same speed?

#

it looks like the left is running faster

#

(the paddle)

uncut glacier Jun 11, 2019, 9:48 AM

#

no "standard" settings have been altered and both are recorded in realtime

#

if you look at the cube going up and down you can see they're the same speed

#

it's the same script

lapis plaza Jun 11, 2019, 9:49 AM

#

they don't move the same speed on that gif

#

also same script doesn't mean they can't move different speed, it depends on how you move them there

uncut glacier Jun 11, 2019, 9:49 AM

#

        int frequency = 20;
        Vector3 change = new Vector3(0, Mathf.Sin(Time.time * frequency), 0);
        rb.MovePosition(gameObject.transform.position + change);

#

inside Update()

#

and they move the same speed to me... the right one is a slight bit behind because 2019 still continues playing when Window isn't active whereas 2017 needs to be active before antyhing happens
so there might be a slight offset on right but they move in sync

lapis plaza Jun 11, 2019, 9:51 AM

#

they start more in sync, then further the clip goes, more they drift

#

at one point they are in sync

#

anyway, to get 1:1 same situation on both, you'd have to lock the rendering/update interval too

#

but for the actual issue

#

I'd check if there's some depenetration value you can tweak

#

I think Unity has one - at least now

uncut glacier Jun 11, 2019, 9:52 AM

#

where would I find this setting?

lapis plaza Jun 11, 2019, 9:52 AM

#

so if it's exploding for that reason, that could be the case

#

would expect it to be on the rigidbody

#

might be only available through API / script

#

here https://docs.unity3d.com/ScriptReference/Rigidbody-maxDepenetrationVelocity.html

#

downside of putting small velocity to that is that then you can risk the object not bouncing from the target and just going through the paddle there

#

but you could still play with that and see if it helps

#

also

#

you really shouldn't move rigidbodies in Update at all

#

even kinematic ones

#

do it on FixedUpdate

#

when you put it on FixedUpdate, it will make physics consistent

#

altho I dunno if that Time.time will work there

#

ah "When called from inside MonoBehaviour's FixedUpdate, returns fixedTime property."

uncut glacier Jun 11, 2019, 9:55 AM

#

ugh, you're saying the complete opposite of someone on answers.unity >.<

#

who to believe...

lapis plaza Jun 11, 2019, 9:56 AM

#

well, I can explain why I say this

#

you know how Unity's main loop works?

uncut glacier Jun 11, 2019, 9:56 AM

#

📎 unknown.png

#

Here's his explanation

#

and uh, somewhat?

#

I've got the printed main loop right in front of me

lapis plaza Jun 11, 2019, 9:57 AM

#

ah, you are now mixing concepts

#

if you read that response, he specifically says you need fixedupdate if you need interactions with normal rigidbodies

uncut glacier Jun 11, 2019, 9:57 AM

#

this answer is on a thread called "How to move a kinematic rigidbody smoothly" Which is what I'm doing

#

oh I interpretted that complete wrong then. I interpretted it as... That if you're forced to use FixedUpdate but still wanna interact with normal rb's you have to increase the rate

lapis plaza Jun 11, 2019, 9:59 AM

#

let me do bit longer explanation. the idea is that when the main loop runs, it first checks how big deltatime was between this and previous time the loop ran (practically time between your Update's)

uncut glacier Jun 11, 2019, 9:59 AM

#

Time.deltaTime, yes?

lapis plaza Jun 11, 2019, 10:00 AM

#

from this time, Unity calculates how many time physics simulation can be run using fixedDeltaTime and what was left from previous frame. so at this point FixedUpdate runs and it can vary how many times based on how long deltaTime you have (yes, Time.deltaTime)

#

only after it has run all physics iterations, it moves to Update

#

but if you move your kinematic rigidbodies only on Update, those previous iterations have to use the values you set to it on your PREVIOUS update (which also is framerate dependent)

#

meaning your dynamic rigidbodies colliding with things that only update on Update get same value many times instead of getting actually true and updated positions on each FixedUpdate

#

so while you still take deltaTime or time into account in Update, it still makes your game play differently at different framerates if you have dynamic rigidbodies in the mix

#

then... the reason why Bunny said to do movement regular Update is because it's practically in sync with the rendering, if you don't have physics interactions, you just want things to be in sync and move smoothly

#

FixedUpdates are NOT in sync with the rendering

#

this is why rigidbodies have that interpolation and extrapolation options so you can render them smoothly despite the actual simulation doesn't run at the same pace as your frames update

#

you can think of fixedupdates as steps that run at virtually fixed intervals (they still don't run at fixed time between them in real time) and updates as variable time steps synced to your frame update speed

#

this probably confused more than helped tho 😄

#

as for the main loop. there's a nice chart at the end of this page: https://docs.unity3d.com/Manual/ExecutionOrder.html

uncut glacier Jun 11, 2019, 10:07 AM

#

fixed update will bascially output the same behaviour no matter what the actual framerate is?

lapis plaza Jun 11, 2019, 10:08 AM

#

as far as physics simulation go, yes

#

it's not 100% deterministic but it's close enough

uncut glacier Jun 11, 2019, 10:08 AM

#

And yeah thats the piece I've got printed in front of me. It confused me alot actually, what you wrote, but I've read it 3 times now and I think i'm starting to understand it.
It's better to understand the bigger picture anyway so I thank you for this explanation

lapis plaza Jun 11, 2019, 10:08 AM

#

so basically if you rely on physics interactions to work the same always, you handle all code that can alter physics on FixedUpdate

uncut glacier Jun 11, 2019, 10:09 AM

#

I changed my script to fixedUpdate though... and now I'm getting even weirder results... :p

lapis plaza Jun 11, 2019, 10:09 AM

#

basically that's also only reason why you even want to use FixedUpdate at all

uncut glacier Jun 11, 2019, 10:09 AM

#

gimme a sec for a gif....

lapis plaza Jun 11, 2019, 10:09 AM

#

put everything else on Update or LateUpdate

uncut glacier Jun 11, 2019, 10:10 AM

#

https://gyazo.com/08abc8ee1ab30f8472d5348f2ead26e7

Gyazo

▶ Play video

#

Only thing changed is Update to FixedUpdate...

#

now my paddles aren't even in sync :p

lapis plaza Jun 11, 2019, 10:12 AM

#

the way you move it isn't all that accurate either

#

I'm frankly surprised if it doesn't drift up or down as the time goes by

uncut glacier Jun 11, 2019, 10:13 AM

#

the thing that bothers me most is wether I'm doing it wrong or right...
It results in completely different results in 2 different version. You'd think that the result, however right or wrong, would result in similar enough results >.<

#

Like why are the results so different, yet scenes and code are the same...

lapis plaza Jun 11, 2019, 10:14 AM

#

well, your code in fixedupdate can run different amount of times from Update

uncut glacier Jun 11, 2019, 10:15 AM

#

right sure but nothing is being done in Update so that shouldn't be a question.?

#

FPS's are similar aswell. both at around 70 consistently

safe flare Jun 11, 2019, 11:32 PM

#

Anyone know what my particles sink through the floor after coming to a stop unless high quality collisions is on? They're just boxes, but they fall through the floor after bouncing once or twice.

quartz wyvern Jun 11, 2019, 11:58 PM

#

i can't get smooth movement on platforms 😢

#

ive tried displacement updates and child transform

#

it still jitters

#

any suggestions on how i can figure out how to solve it

idle rock Jun 12, 2019, 1:47 AM

#

Hello, Pretty new to unity, doing a 2D top down project. Does Raycast fall under physics? I'm doing a Debug.DrawRay to show where it is pointing but it seems to point in often random directions, not related to my objects. I have a Ray2D with transform.position and player.transform.position and then Debug.DrawRay is ray.origin and ray.direction * ray.Distance .. (also first time asking a question, not sure if there are specific things I am missing from the question)

languid comet Jun 12, 2019, 1:50 AM

#

if you're using 2D colliders, the raycast would be Physics2D.Raycast() rather than Physics.Raycast2D (i've ran into this confusion as well, hope this helps)

idle rock Jun 12, 2019, 1:50 AM

#

I am using Physics2D.Raycast, though not because I know to do that, but because the code i copied/tutorial i followed used it.. lol

languid comet Jun 12, 2019, 1:51 AM

#

so what is the problem exactly?

idle rock Jun 12, 2019, 1:52 AM

#

As my player object approaches the "portal" object in this case, the ray actually moves away from the player object, at about the same rate I approach. It starts out pointing up/off in a random direction, and as I approach, goes in a clockwise direction, if I move away, goes anti clockwise.

#

I will see if i can do a gif or something.

languid comet Jun 12, 2019, 1:52 AM

#

that'd help, thanks

#

ping me once you got it, since it might take a bit

idle rock Jun 12, 2019, 1:53 AM

#

kk

#

@languid comet https://gfycat.com/jovialaccuratebirdofparadise - let me know if that is not helping, or if you need to see something else., - also this is the code associated with the "portal". Basically I want the portal to be invisible unless you are within line of sight, and within a certain distance (5f in this case), touching the portal generate a new "random" level. https://pastebin.com/a5QQcX3Z

Gfycat

Pastebin

[C#] using System.Collections; using System.Collections.Generic; ...

languid comet Jun 12, 2019, 2:04 AM

#

hmm

#

the line seems to never be pointing in the right direction

idle rock Jun 12, 2019, 2:06 AM

#

yeah, it should point to my player all the time, but it never seems to. I have considered redoing the raycasting and having the player cast to the portal and set the portal to visible if they hit it, but there could eventually be a lot of items (enemies etc) that it needs to do this with, it'll kind of be a fog of war.. so unsure if that will cause performance issues later. But I can't even get this simple one to work.

languid comet Jun 12, 2019, 2:07 AM

#

so what is the point of the raycast exactly

#

do you want a line to appear in the game between the player and the portal?

idle rock Jun 12, 2019, 2:07 AM

#

to tell if the portal and player are in line of sight and within a specific distance, if so, make the portal visible.

languid comet Jun 12, 2019, 2:08 AM

#

or do you want to check the distance between the two

#

ahhh

#

ok i know

idle rock Jun 12, 2019, 2:08 AM

#

check the distance and los. the map/walls are procedurally generated so it needs to not show it if the walls block los.

languid comet Jun 12, 2019, 2:08 AM

#

you should be going for Vector3.Distance() rather than telling the length of a ray

#

have a variable something like

#

float minPortalDist = 1

#

and say in update

#

oh fuck

#

shit ok

#

never mind i'm a dumbass

#

hold up

hollow echo Jun 12, 2019, 2:12 AM

#

@idle rock can you just post the code behind your raycast?

#

(surround it in three backticks to get code formatting, with the first line being cs to get C# formatting)

idle rock Jun 12, 2019, 2:12 AM

#

kk one sec.

#

tells me its over the limit, is a C# formatted pastebin link ok ?

hollow echo Jun 12, 2019, 2:14 AM

#

sure, but I don't really think you need to send that much code 😛

#

hastebin is also a much nicer website 😄

idle rock Jun 12, 2019, 2:14 AM

#

(you assume i know which bit is important.. lol)

#

https://hastebin.com/ituropubed.cpp 😄

hollow echo Jun 12, 2019, 2:17 AM

#

player.transform.position is not a direction

#

When you construct the ray, it takes a position, and a direction

#

the direction you would want is:

(player.transform.position - transform.position).normalized```

idle rock Jun 12, 2019, 2:18 AM

#

ahh ok, so maybe that thing that Copper showed me above, the Vector3.Direction() is what I need ?

#

ok sweet, i will try that. I thought it might be something like that.. i also thought maybe it would magically work that out as unity magically seems to most everything else sometimes. lol.

#

would Vector3.Distance() do the same thing? (given the 2 positions) ?

#

oh nice, it's spot on.

hollow echo Jun 12, 2019, 2:20 AM

#

No, it's entirely unrelated

#

It gets the distance between two points, the logic above gets a normalised direction vector from point A to B:

(B - A).normalized```

#

The Ray2D constructor actually normalises the vector already so you can even skip that step and just write B - A

#

Here's the docs page talking about this sort of thing https://docs.unity3d.com/Manual/DirectionDistanceFromOneObjectToAnother.html

idle rock Jun 12, 2019, 2:23 AM

#

nice, yep it makes sense. and now, I see the raycast, but even if I am within the 5f and there is a wall in the way, the portal doesnt show up... when i pop around the wall, boom.. shows up. so question on the concept I am doing. Is it better to have the player object raycast to all the things it's keep ing track of, enemies, loot, portals etc, or to have each of them raycast to the player and just show themselves once they can see the player or are inside the view range? Is there a better way to do this kind of fog of war ?

#

Especially if I could have 40 or 50 or more objects on screen in a really busy part of the dungeon. I kind of want to "turn off" some things that are outside of view range. Eventually the enemies will have a flocking type AI and want to follow/approach the player, so it could get busy.

quartz wyvern Jun 12, 2019, 10:45 PM

#

is it 100% certain that you can move rigidbodies by its transform if its kinematic ?

#

because i cant understand why im getting problems with my scene

frigid lake Jun 13, 2019, 4:39 AM

#

What problems are you getting

quartz wyvern Jun 13, 2019, 5:22 AM

#

ive fixed some of the issues

#

but its still detecting a collision where two colliders touch

#

ive adjusted the contact value in settings to like 1 and 0.0000001

#

both extremes still do the same thing

#

im trying to roll a ball over the colliders but edge where the ground colliders are adjoining its colliding =/

#

see here

📎 capture.gif

#

its acting like its hitting an invisible object where the two floor tiles are touching

frigid lake Jun 13, 2019, 6:43 AM

#

Can you select the floor colliders too, and post ? Hard to tell which colliders you are talking about

strong plaza Jun 13, 2019, 12:20 PM

#

sure you can move them with the transform, the transform change will force the rigidbody to be updated too, even if kinematic

#

but a direct transform change behaves like "teleportation" of the body, so keep that in mind

#

meaning, teleporting a too long distance might mean you miss collisions, I don't know if the interpolation setting would account for position changes made by the transform itself, but I doubt it

muted rivet Jun 13, 2019, 5:58 PM

#

Hello everyone,
I'm trying to write a script for my character to "dash forward" when player hits "E"
This code works ok, but the problem is my character teleports to the destination. How can I make it a bit slower? Something like Genji in Overwatch
Thank you

        moveDirection = new Vector3(0f, 0f, 20f);
        moveDirection *= dashDistance;
        if (Input.GetKeyDown(KeyCode.E))
        {
            characterController.Move(transform.rotation * moveDirection * Time.deltaTime);
        }```

vale dagger Jun 14, 2019, 10:39 AM

#

Any idea how to stop a NavMeshAgent from getting pushed by my character? (not sure if #⚛️┃physics related but it looks appropriate)

frigid pier Jun 14, 2019, 11:32 AM

#

you can increase its mass

vale dagger Jun 14, 2019, 11:34 AM

#

It doesn't have any mass. He doesn't have a rigidbody, just a navmesh boi doing navmesh things 😦

#

Unless I'm missing something and NavMeshActors inherit some kind of mass... Doesn't have any gravity effects too, when he's near my NavMesh he snaps on it and when I move him in the air (away from the mesh) he just hovers

frigid pier Jun 14, 2019, 11:39 AM

#

They can have rigidbodies, IIRC mass will only be used in interactions with other objects, won't affect their settings. So you can make them heavy enough not to be pushed around.

vale dagger Jun 14, 2019, 12:26 PM

#

Turns out my character has a Rigidbody 🤔

#

Well at least that's what prototypes are for! To use the wrong stuff and then toss them away to start from scratch! Right guys? ... No? Oh well 😛

manic stream Jun 16, 2019, 11:51 AM

#

Hello everyone. I have a question. I have a fractured cube (done in C4D) in Unity. Each fracture part has a rigid body and mesh collider (with convex) enabled. When I hit Play the entire object falls apart. How can I stop it from collapsing and only react to collisions of other objects? Thanks!

frigid pier Jun 16, 2019, 11:57 AM

#

Convex will make some parts intersect. So they will try to push themselves out.

manic stream Jun 16, 2019, 12:00 PM

#

When I disabled Convex and try to play I get an error saying "non convex mesh collider with non-kinematic rigidbody is no longer supported"

frigid pier Jun 16, 2019, 12:00 PM

#

You can try cutting it in a way that doesn't create parts with hollows

manic stream Jun 16, 2019, 12:00 PM

#

It doesn't have hollows

frigid pier Jun 16, 2019, 12:00 PM

#

yea, dynamic object can't be non-convex

manic stream Jun 16, 2019, 12:00 PM

#

It's a voronoi fracture

frigid pier Jun 16, 2019, 12:02 PM

#

You can try using slightly scaled down collider if they don't intersect

manic stream Jun 16, 2019, 12:02 PM

#

OK. I will try that

hollow echo Jun 16, 2019, 12:02 PM

#

could also just have a cube with the fractured sub objects disabled, and swap when you have the collision you need

manic stream Jun 16, 2019, 12:03 PM

#

Yes, I know what you mean vertx, but I wanted to have the effect of "shooting at the wall" where parts of the wall fall off

#

If you know what I mean

hollow echo Jun 16, 2019, 12:04 PM

#

You could make all your objects kinematic, and then disable that property on the pieces you find relevant when the collision occurs

#

That is, if your object isn't moving until the collision events

manic stream Jun 16, 2019, 12:06 PM

#

I guess that would work. I will give it a go. Thanks for the tips guys

sly violet Jun 16, 2019, 3:58 PM

#

@manic stream If it's just falling apart and not exploding apart, you could try connecting them with FixedJoints that have relatively low Break Force and Break Torque. That would be a more realistic way of modeling it.

manic stream Jun 16, 2019, 6:12 PM

#

Hey Pyrian. Yes, it's just falling apart. I will try FixedJoints. Thanks a lot

placid stirrup Jun 16, 2019, 6:57 PM

#

Hello, anyone had any luck detecting collision between 2 balls in unity physics (ECS)?? I have been struggling with that for a while, I am just trying to get a callback whenever 2 balls collide, any pointers/references would be very much appreciated :). I have been reading this doc https://docs.unity3d.com/Packages/com.unity.physics@0.1/manual/collision_queries.html multiple times but I can't achieve simple 2 body collision detection

marble rose Jun 16, 2019, 7:24 PM

#

@placid stirrup For me collisions are not working when both bodies are kinematic. Maybe that's the cause

placid stirrup Jun 16, 2019, 7:25 PM

#

@marble rose only one of my objects is kinematic

#

if only there was an equivalency tutorial like the equivalent of OnTriggerEnter, or OnCollissionEnter, it's so confusing since I just recently started exploring ECS

marble rose Jun 16, 2019, 7:29 PM

#

@placid stirrup All right, you should be able to get it with ICollisionEventsJob

placid stirrup Jun 16, 2019, 7:34 PM

#

thanks for the pointer, I will go through the demo project, and see if I can get the callback I want

cosmic mica Jun 17, 2019, 10:06 AM

#

Why is most of physics work done in the frame containing fixedupdate instead of spreading over frames? In our case we have fixedupdate set at 10hz, but in practice the peaks are the same as the default 50hz, just less frequent.

lapis plaza Jun 17, 2019, 12:06 PM

#

You sure about that?

#

Wait, are you talking about DOTS physics package @cosmic mica ?

#

I ask because it's physics stepping is faulty atm

#

For regular physics, if that happens there is something funky going on

#

I wouldnt expect Unity to have a bug on such simple logic

#

Basically how the thing works is that each time in the main loop Unity adds deltatime to physics counter, timebank whatever you want to call it, and then checks how many fixed timesteps fits to that timebank, it then removes physics step*fixedDeltaTime from it and then runs fixedupdates as many time it thought it could fit in available time

#

Running physx at 10Hz is not a good idea though, you'd need at least 20-30 Hz to keep it stable, depending on your gameplay

cosmic mica Jun 17, 2019, 12:21 PM

#

@lapis plaza I meant regular unity physics

#

Well for our game 10 hz works well enough, though we may increase it to 15

#

It's in space so mostly for debris and crashing into various things

oak axle Jun 17, 2019, 5:31 PM

#

Hey guys, does anyone know if there "stylized" vehicle packages out there (mario kart-esque handling loops, heavily tilted roads)? preferably working in 2019.1.4. I found randomation which looks perfect, but its only supported with up to Unity 5.6. Any suggestions would be super appreciated. Thanks guys

lapis plaza Jun 17, 2019, 5:43 PM

#

should be somewhat trivial to port it to 2018 or 2019

#

also since it's open source an on github now, chances are that some have already done that and shared it

#

hmmmm, actually it doesn't have

#

but still, shouldn't be too hard to make it work

uncut glacier Jun 18, 2019, 12:27 PM

#

is it better to call rb.MovePosition/Rotation in Update or FixedUpdate?

quartz wyvern Jun 19, 2019, 2:24 AM

#

fixed

#

physics sim only runs on the fixed rate so if you update in update method i believe it might overstep collisions

uncut glacier Jun 19, 2019, 7:52 AM

#

got it, thanks!

I got into a new issue though, when I throw a character with joints and colliders on these joint to the same character, half the time they bug out and go flying into infinity. I already set all of their rigidbodies' max depenetrationvelocity to like 10. but it doesn't seem to work... What's the cause of this and how do I fix it?

uncut glacier Jun 19, 2019, 8:33 AM

#

every joint also has a Rigidbody

wraith minnow Jun 19, 2019, 7:22 PM

#

guys how to do 2D physics 😄 does someone have an script for that?

lapis plaza Jun 19, 2019, 7:32 PM

#

you keep asking for people to send you scripts for thing x and y.

#

this is not what gamedev is about

wraith minnow Jun 19, 2019, 7:36 PM

#

yeah but i wanna to do different things than coping script for 40 mins.... when icant get it and im not in the right mood for it... @lapis plaza

#

for example level design

wraith minnow Jun 19, 2019, 7:56 PM

#

And yeah.... im completly beginner dude....

vale valve Jun 21, 2019, 5:01 AM

#

trying to get a simple jump sorted but on play my player character immediately starts hovering upwards instead on button down like intended

#

 void Update()
    {
        print(Input.GetAxis("Horizontal"));
        inputVector = new Vector3(Input.GetAxisRaw("Horizontal") * 10f, 0, 0);

        if (Input.GetButton("Jump")) ;

        {

            //playerBody.AddForce(new Vector3(0, 1, 0), ForceMode.Impulse);
            Physics.gravity = new Vector3(0, -5.0F, 0);

        }

        
    }

frigid pier Jun 21, 2019, 5:09 AM

#

@vale valve You are changing physics for the whole universe. You want to collect all input in Update() and apply it and everything physics related in FixedUpdate() , using https://docs.unity3d.com/ScriptReference/Rigidbody2D.AddForce.html for the jump and side movement.

#

Using physical model you also want to have friction on surface and when in the air to apply additional drag on the character (switching from friction to drag to slow down player) and adding additional downforce to compensate vertical drag

#

Also setting at least double gravity works well for platformers

#

https://docs.unity3d.com/ScriptReference/MonoBehaviour.OnCollisionStay2D.html to detect if you are in the air

vale valve Jun 21, 2019, 5:14 AM

#

oh, okay. thanks. I already have playerBody.velocity = inputVector; in fixedupdate for the horizontal but I'll move the other stuff there, thanks

frigid pier Jun 21, 2019, 5:15 AM

#

changing velocity directly wipes out any previous object interaction

#

If you want to work with physics use forces

vale valve Jun 21, 2019, 5:16 AM

#

hmm, alright. good to know

obsidian willow Jun 21, 2019, 4:47 PM

#

Hey guys, how are you? I got a question..do you guys use the GameObject Scale based on real life or use it as a property to literally only change the size of the object? I mean, Unity uses Scale to apply phisics proccess and recomends to use the Scale unit as meters (if I'm not wrong), but I don't usually see devs using this approach.

maiden grove Jun 21, 2019, 5:20 PM

#

I think its fine to generally look at world space as meters and have your models imported to reflect that

#

generally speaking - we rarely modify transform.scale aside from special effects, and try and keep things 1:1 with how the model was exported

obsidian willow Jun 21, 2019, 6:09 PM

#

@maiden grove And in case of sprites?

maiden grove Jun 21, 2019, 6:10 PM

#

same I think - you'll generally want to try and keep it pixel perfect

sly violet Jun 21, 2019, 8:53 PM

#

Generally speaking you only want to use the Unity Transform Scale for rapid prototyping/iteration and for things that will dynamically change their scale in game. In all but a handful of other scenarios, you're just better off scaling the asset in some other way, usually outside of Unity altogether.

obsidian willow Jun 21, 2019, 8:59 PM

#

By consequence, all the objects in scene will have the same scale (0,0,0) and if i need to make some object behave different of other I will handle mass, drag and force values right?

sly violet Jun 21, 2019, 9:00 PM

#

I recommend scale (1,1,1). You won't like the results of scale (0,0,0). 😄

#

But otherwise, yes, that's about right.

obsidian willow Jun 21, 2019, 9:15 PM

#

@sly violet (1,1,1), that was what I mean XDDD

stuck bay Jun 21, 2019, 9:15 PM

#

hi I have qestion about baouncing ball

obsidian willow Jun 21, 2019, 9:15 PM

#

Thanks for the help o/

stuck bay Jun 21, 2019, 9:17 PM

#

I've made a ball moving by addforce function and for each step script create new ground for the character but after some time ball start bounce without any reason. I've made physics material with 0,0,0 for ground but it's doesn't help with this issue maybe anyone has similar problem?

sly violet Jun 21, 2019, 11:24 PM

#

Could be an issue with ground creation. "T"-shaped collider intersections are flat in theory but in physics-engines objects moving across them will almost always hit the corner.

stuck bay Jun 22, 2019, 8:02 AM

#

So I have a 2d collision circle and a ridgid body 2d component on a "bullet"... this bullet can go through projectiles of certain types (destroying the other projectile in the process). However, I notice that when a collision happens, the bullet just... stops moving... unless I call my Start(); function again which sets the velocity again.

#

er i guess how can i have rb2d and collider2d objects pass thru each other

sly violet Jun 22, 2019, 8:11 AM

#

Sounds like you're having a regular collision with zero bounciness? Look, if you have a non-trigger collider and destroy another projectile in the OnCollisionEnter events, it's going to impact that projectile THEN destroy it and not vice-versa. If you want it to be unaffected by the other projectile, you'll need it to be a trigger-collider. If you don't want it to be a trigger collider (perhaps because you want it to impart force to other targets) you can give it a child GameObject with a trigger collider and leverage Layers such that the child interacts with the "don't affect me" projectiles. Either way, you'll need to detect the event with an OnTriggerEnter.

stuck bay Jun 22, 2019, 8:20 AM

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gee thanks @sly violet i'll try checking "is trigger" under my collision component and rename OnCollisionEnter to OnTriggerEnter

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working great thanks ❤

inland birch Jun 22, 2019, 4:05 PM

#

I’m having an issue with the animator

#

It’s making my player stop whenever it transitions to the walk animation

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If anyone knows which aspects of the animator can affect the actual movement (not the animation but like speed)

#

Please let me know how I can fix this

desert lichen Jun 22, 2019, 4:19 PM

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@inland birch is your animator's root motion property checked in the inspector?

inland birch Jun 22, 2019, 4:19 PM

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Yes it is

desert lichen Jun 22, 2019, 4:19 PM

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Uncheck

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Probably your walk animation has not root motion

inland birch Jun 22, 2019, 4:20 PM

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I tried that, and it gets really weird

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I had it working with root motion checked

desert lichen Jun 22, 2019, 4:21 PM

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Generally its better controlling characters without root motion, it is easier to control and adds a gamey feel to it

inland birch Jun 22, 2019, 4:21 PM

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Maybe, I’m fairly new to this

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I should also mention it’s 2D

desert lichen Jun 22, 2019, 4:21 PM

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Oh

inland birch Jun 22, 2019, 4:22 PM

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So all I really need is simple left right up down

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Whenever it transitions to walking animation the speed turns into 0

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And I have no idea why

autumn jetty Jun 23, 2019, 10:46 AM

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Anyone know in the new ECS system if you can raycast vs a single collider? Similar as you can do with the old one with collider.Raycast() ?
(edit) Seems like it was similar to the old way of doing it, not on the assetBlob but on the colliding class : ) Not sure if you need to create an assetBlob however.

autumn jetty Jun 23, 2019, 5:53 PM

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Again at it, anyone know what the "Physics.ComputePenetration" answer is in the new Physics system?

autumn jetty Jun 24, 2019, 9:17 AM

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Hmm, so maybe anyone know if the "SurfaceNormal" in queries the normal of the point hit on a collider, or the inverse "ray" from the hit poisition of the collider to the query starting position? I really don't know if my parsing of the doc correct x)
SurfaceNormal : The normal to the surface at the point of intersection, in world space.

mighty sluice Jun 24, 2019, 11:48 AM

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Does the Unity Physics "Drag" property take into account object dimensions?

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Surely it uses some form of surface area, but does it actually take a silhouette in the direction of travel?

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in other words, would a thin object have lower drag if traveling along its thin dimension?

#

i guess i could find out

#

and the answer is : no

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it does not

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I was thinking that if it did, then it would be possible to make physics based flapping flyers

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but more practically, it would also work for swimming

lapis plaza Jun 24, 2019, 11:54 AM

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@mighty sluice first of all

#

it's not actually drag

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it's linear damping

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at least the new DOTS physics package calls it with it's real name

mighty sluice Jun 24, 2019, 11:54 AM

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lol

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i gguess it would be pretty easy to implement

lapis plaza Jun 24, 2019, 11:55 AM

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it basically does is velocity *= 1 - clamp( 0, 1, drag)

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in pseudocode

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yes, it's super simple

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if you want actual drag, you have to build it yourself with custom forces

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this is kinda issue I have with Unity's naming conventions

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they've tried to oversimplify things by calling them with terms that most people know from somewhere

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but calling damping drag is fundamentally wrong if you know any physics

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engine is full of similar things

vale valve Jun 24, 2019, 1:28 PM

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okay, I have an ultra basic barebones jump implemented in my 2d game but I want to make it actually usable. https://www.youtube.com/watch?v=7KiK0Aqtmzc I like the ideas this has for jumping but remember reading that directly manipulating gravity isn't a good idea so I'm unsure how to implement it

YouTube

Board To Bits Games

Better Jumping in Unity With Four Lines of Code

Eliminate the low-gravity feeling of a physics based jump with four lines of code. Actually, just two lines. The other two give you the ability to control ju...

▶ Play video

lapis plaza Jun 24, 2019, 2:03 PM

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jump tweaks with direct gravity manipulation? 😄

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who came up with that

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I guess it can work if you only have one dynamic rigidbody in total in your scene

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but most games are not like that

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you'd be better off just not applying any gravity to that rigidbody in that case and just implement it yourself then

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just use AddForce for it on FixedUpdate

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F = ma, where m is mass and a is acceleration, in this case your gravity value

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or just use AddForce with acceleration mode directly and you don't even have to take mass into account

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@vale valve

vale valve Jun 24, 2019, 2:08 PM

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Okay, I'll look into that, thank you!

autumn jetty Jun 24, 2019, 3:07 PM

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Anyone knows if there's anything like "Physics.ComputePenetration" in the new system?

craggy peak Jun 24, 2019, 6:28 PM

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Hi People, im developing a Tennis Game. I already do the ball colision with racket, and the shot manager for top spin/slice, etc. But the ball movement feels strange. Also i dont know how to do the service..

📎 unknown.png

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I want to emulate a Physics like this https://www.youtube.com/watch?v=c-yP206YjXc

YouTube

kreature kodeyellow

Dream Match Tennis Pro - Insane Difficulty

I got drowsy and couldn't keep up with the AI. It was a fun match and I played it till the end and walked out a proud loser. If only Top Spin 4 was ported to...

▶ Play video

#

I read this post but i didnt understand, literally, anything https://www.physicsforums.com/threads/trajectory-of-a-projectile-that-must-clear-an-obstruction.938077/

Physics Forums | Science Articles, Homework Help, Discussion

Trajectory of a Projectile that must clear an obstruction

I am trying to solve for Vy with given Vx. I know how to do this for the BLUE trajectory line, but I do not know how to solve this if there is an obstruction in the way (like the gray wall).

My givens are:
X1
X2
Y1
Y2
Vx
Gravity

Do I need to solve for the blue trajectory t...

#

Its the Magnus Force the correct answer ? Im feel so lose with this

autumn jetty Jun 24, 2019, 8:38 PM

#

@craggy peak Usually when it comes to sport, there is a lot of already done calculations in terms of physics. What forces act on it etc, what different constants exists with more. If you want to learn the basics I would go look in some book like "physics for game programmers".

#

Usually you can just do a quick google to get the constants and forces right.

craggy peak Jun 24, 2019, 8:41 PM

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Trully, i speak spanish, so is very difficult to learn because there is no much tutorials and guide about physics. Hopefully i speak and read english good, or i think so haha

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Yeh bro, i did a quick google search for tennis ball physics but i didnt find anything that i can use to emulate the ball like in that game

autumn jetty Jun 24, 2019, 8:50 PM

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@craggy peak Some basic things what happens to the ball http://ffden-2.phys.uaf.edu/webproj/211_fall_2014/Max_Hesser-Knoll/max_hesserknoll/Intro.htm.

craggy peak Jun 24, 2019, 8:52 PM

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Thanks @autumn jetty , i will take a look and try to implement in my code. Only with see the text Im start to feeling a headche haha

autumn jetty Jun 24, 2019, 8:53 PM

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Don't think it gives any specific code, or force equations in it, but check its sources. I saw some friction coefficients. But I would recommend reading a book about the force equations if you don't already know them. Ball physics in general^^

craggy peak Jun 24, 2019, 8:54 PM

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And how i can do the serve ? Like bounce ball, throw up and then hit, is like a forehand and backhand detecting the collide and then move the ball with forces, right ?

#

The problem is that i want to do more than one character, but i need to do the base then implement a general function to the other chars, right?

#

Yes, im reading, it explain how the ball forces are applied, so i need to understand that to apply in my code

autumn jetty Jun 24, 2019, 8:55 PM

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Depends on how much simulation you want I guess? x)

craggy peak Jun 24, 2019, 8:55 PM

#

The most possible for my brain

autumn jetty Jun 24, 2019, 8:56 PM

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VR? Or controllers? What input do you have? What parameters are most interesting for a serve?

craggy peak Jun 24, 2019, 8:57 PM

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Controllers, keyboard.. bounce the ball its a detail, i dont need it. only i need the ball in hand of player, and throw up so i can hit with an animation, and then collide

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But again, the problems are the physics when i hit the ball

mighty sluice Jun 25, 2019, 3:35 AM

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Does anyone know anything about JointMotor.targetVelocity?

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i understand that it "uses a force to achieve the target velocity"

#

but why?

#

is it just a way of limiting the maximum speed?

#

I'm trying to create a limb that uses two opposing joint forces (one motor and one spring), but the way velocity interacts with them is disturbingly unpredictable

#

is there a way to disable the targetVelocity parameter so that the motor applies a linear force?

#

or alternatively, is it possible to use a JointDrive instead of a JointMotor (hingeJoint vs CongifurableJoint) to achieve a linear force output?

#

as far as i can tell both the X andYZ and Slerp drives use position springs (which increase force applied with distance from the target angle or position

lapis plaza Jun 25, 2019, 3:16 PM

#

from https://forum.unity.com/threads/nvidia-physx-plugin-preview.645004/#post-4684205:
We're ready to share a different approach to exposing NVIDIA PhysX 4.1 inside Unity: we now have a low-level C# interface directly to the PhysX 4.1 API.

#

this is physx 4.1 plugin from nvidia, not the experimental physx 4 unity integration from Unity

#

📎 unknown.png

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this is clearly being limited by unity's rendering at this point

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16k rigidbodies simulated on gpu

autumn jetty Jun 25, 2019, 4:02 PM

#

Anyone know what structure holds the labels of Physics Category Names? I basically want to have them in inspector at some SO so I don't have to type it manually in code...

fringe locust Jun 27, 2019, 7:13 PM

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Hey, quick question: if two gameobjects have a rigidbody with the isKinematic property set to false, will OnCollisionEnter ever be called?

gleaming lily Jun 27, 2019, 7:47 PM

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No.

#

https://docs.unity3d.com/Manual/CollidersOverview.html

#

there is a table there

stone palm Jun 28, 2019, 1:18 AM

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So i'm building a character controller for my action spell casting game, I have it working really well with double jumps, dashes, slides sprinting and variable run speeds depending on the build up. I'm not using root motion tho and theres a slight sliding that bothers me. Is there a way to fix that without root motion?

autumn jetty Jun 28, 2019, 3:08 PM

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@stone palm Explain what you mean with sliding, have you checked your inputs vs some simpler controller to see that they sampled correctly? If so post some code so we can see what you got going.

stone palm Jun 28, 2019, 3:42 PM

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My issue is that I'm not using root motion for animations, I'm doing everything using various velocity in code so that I can later do net play easier. Because I'm using in place animations the steps dont always line up or looks like feet are sliding. Is there a way to fix that without using root motion and still using my physics based controller

autumn jetty Jun 28, 2019, 8:28 PM

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@stone palm If your root motion is synced and driven by inputs I don't see why it shouldn't be possible to be done with net code. You're asking if there is a way to fix sliding which is a artefact dependent on animations to be in sync with physics without looking at animations to drive physics? In that case look at physics to drive animations?

fathom ledge Jun 29, 2019, 11:51 AM

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Are there any good resources to learn more about the new Havoc physics?

lapis plaza Jun 29, 2019, 11:52 AM

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you mean DOTS Unity Physics package or the actual Havok physics that is yet to arrive this summer?

#

@fathom ledge

fathom ledge Jun 29, 2019, 11:53 AM

#

https://blogs.unity3d.com/2019/03/19/announcing-unity-and-havok-physics-for-dots/

Unity Technologies Blog

Announcing Unity and Havok Physics for DOTS – Unity Blog

During our GDC Keynote, we announced our partnership with Havok to build a next-generation physics system for Unity. Today, we want to give you more detail...

lapis plaza Jun 29, 2019, 11:53 AM

#

that doesn't answer to my question

#

that blog post talks about both things I mentioned

fathom ledge Jun 29, 2019, 11:53 AM

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I still haven't finished talking xD

lapis plaza Jun 29, 2019, 11:53 AM

#

so I'm asking which one you are asking about

#

ah

fathom ledge Jun 29, 2019, 11:53 AM

#

Oh yeah I didn't know they are 2

lapis plaza Jun 29, 2019, 11:53 AM

#

well, if you read that blog post, it should be obvious 😄

#

anyway

#

(DOTS) Unity Physics package is available already, it's in preview

#

Havok integration hasn't arrived yet

#

Havok will come with some cost

#

nobody knows what it will be

#

but I'd suspect they do some revenue share or subscription

fathom ledge Jun 29, 2019, 11:55 AM

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I see

#

Have you looked into the DOTS package with networking?

lapis plaza Jun 29, 2019, 11:56 AM

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nah, it's too early for that

#

they don't even have fixed timestepping working right now

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so their current version has physics that are directly tied to your framerate

#

I'm evaluating the package though, but it's nowhere near production ready

#

also while Unity Physics is designed to be deterministic, it'll not be that in crossplatform setup as burst doesn't support it yet

#

Burst is supposedly deterministic on same platform already but haven't seen anyone actually confirm that in practical testing

#

determinism itself bring new opportunities on the netcode side

fathom ledge Jun 29, 2019, 11:58 AM

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Right but I've not seen anything deterministic so far

lapis plaza Jun 29, 2019, 11:58 AM

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for example if you have a game server, you can just have clients send their player inputs to the server and let the server sim it from that

fathom ledge Jun 29, 2019, 11:59 AM

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I thought DOTS would bring something to the table

lapis plaza Jun 29, 2019, 11:59 AM

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well, you'd do that anyway in such setup but in this case, you don't have to send constantly the correct data back to the client as the sims will not drift

#

well, that's Unity Physics for you

#

it's technically there already, but like mentioned, it's still very early

#

there could have been some things on the Unity Physics that they still need to fix for full determinism but the ultimate goal is that it'll be able to do that

#

actual Havok integration will never support crossplatform determinism

#

only this new Unity Physics package will

#

but even that will happen somewhere next winter at earliest

fathom ledge Jun 29, 2019, 12:16 PM

#

Aha I see

inland grail Jul 1, 2019, 10:52 PM

#

Hi everyone, any masters of Unity #⚛️┃physics interested in doing some paid work? Send me a DM thanks.

bleak folio Jul 2, 2019, 9:24 AM

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Some more details about the kind of work required would be great

wispy wharf Jul 2, 2019, 3:21 PM

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Hi! In the joint drive, what is the unit for the maximum force? is it in newton?

sly violet Jul 2, 2019, 8:49 PM

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Neither distance nor mass have units in Unity, but if you think of them as meters and kilograms then force is in newtons, yes.

wispy wharf Jul 2, 2019, 8:51 PM

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Ah, I see... because I find it kinda weird that in the WalkerAgent example from ml-agents the maximum force limit is set to 25000, which seems way too high if it is in Newton...

scenic dock Jul 3, 2019, 5:48 AM

#

anyone been using simulated physics on a character controller?

quartz wyvern Jul 3, 2019, 7:03 AM

#

any one buoyancy physics before?

#

i cant get mine to look right it goes up and down too fast

frigid pier Jul 3, 2019, 7:16 AM

#

@quartz wyvern Stress test I made some time ago on my old PC using ideas from this talk https://youtu.be/OOeA0pJ8Y2s?t=360. There are 500 objects, each raycasting individually for buoyancy.

📎 500_objects_test_2017-07-12_14-44-48.gif

kind marsh Jul 3, 2019, 1:11 PM

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Does anyone know what space HingeJoint.angle is expressed in? When rotating the parent of a hinge joint (it's connected body), its angle changes, even though the local rotation stays put... I don't understand how that angle is calculated. I need it to dynamically set the hinge's spring.targetPosition.

unborn narwhal Jul 3, 2019, 1:21 PM

#

@quartz wyvern https://www.youtube.com/watch?v=_Ij24zRI9J0

YouTube

DitzelGames

Create Octave Water Waves - Unity Ocean Tutorial 1/4

In this tutorial we will create a beautiful water scene. The tutorial is divided into 4 chapters. Every chapter will explain how a specific step to create th...

▶ Play video

wispy wharf Jul 3, 2019, 2:22 PM

#

Does anyone know why using joint.targetRotation is not doing anything for me?

#

I set the configurable joint drive to slerp and the X rotation is limited with limits from -60 to 120. I do joint.targetRotation = Quaternion.Euler(120, 0, 0);

#

no matter what values I put in there, I don't see it updating..

wispy wharf Jul 3, 2019, 3:09 PM

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ok I figured out it was because I set the position damper to 0 in the slerp drive....

#

can someone explain to me what position and spring damper do and why they are important for setting a target rotation?

wispy wharf Jul 3, 2019, 3:45 PM

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also why is it that the angular limit drops back to 177 when I enter something bigger than that as soon as a I press start_

plain swift Jul 3, 2019, 3:55 PM

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I'm trying to make the player collide with a tilemap, but when I add the tilemap collider 2d the player ignores it, and if I try a box collider it creates collision, but it make the whole area of the tiles and the spaces in between a collider

frank forge Jul 3, 2019, 5:04 PM

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@plain swift dm’d you

quartz wyvern Jul 3, 2019, 7:59 PM

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@frigid pier @unborn narwhal thanks for the links i will check them out

tender gulch Jul 4, 2019, 12:09 PM

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Hello, anyone can help with setting up a ragdoll on an npc?

#

I have a problem that the parent gameobject( that contains colliders and logic) doesn't move together with the ragdoll...

#

https://cdn.discordapp.com/attachments/497872424281440267/596310055033503774/unknown.png

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that's the structure of the npc. The ragdoll components are assigned to the bones in armature.

wispy wharf Jul 4, 2019, 8:06 PM

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You have to move the parent and not the childs to move everything together. Moving only a child will only move that child and its children

obsidian geode Jul 4, 2019, 8:12 PM

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id like to use two mesh colliders of the same mesh, one convex for simple collisions with the gameworld and so on and one concave for higher precision projectile collisions

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not sure how to separate the two

wispy wharf Jul 4, 2019, 8:13 PM

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Can someone explain to me how joint.targetRotation is implemented? It only seems to work when setting the position spring value in the joint to something like 5000, when it should also work when it's set to 0 if the force can be big enough to overcome gravity. The problem with setting the position spring to a high value like this is that gravity is ignored, i.e. holding a pose requires no force whatsoever for the agent, just going to that position requires some.

#

@obsidian geode here they say you can't have 2 colliders of the same type on an object: https://answers.unity.com/questions/529918/is-it-possible-to-have-multiple-mesh-colliders-on.html

Is it possible to have multiple Mesh Colliders on a Gameobject? - ...

Unity is the ultimate game development platform. Use Unity to build high-quality 3D and 2D games, deploy them across mobile, desktop, VR/AR, consoles or the Web, and connect with loyal and enthusiastic players and customers.

obsidian geode Jul 4, 2019, 8:15 PM

#

oh. dang

wispy wharf Jul 4, 2019, 8:15 PM

#

So you could have one mesh collider and maybe one other collider

#

Maybe sphere or capsule or something

#

For the less detailed one

#

If anyone has the answer about my joint.targetRotation problem please let me know

sly violet Jul 4, 2019, 8:30 PM

#

@obsidian geode Non-convex mesh colliders are only supported on GameObjects without a rigidbody. Sometimes you can divide your mesh into separate convex colliders on child objects. Another thing you could try is having a non-convex collider on a separate GameObject, and detect when a projectile triggers against your normal convex collider, then teleport in your non-convex collider and see if it triggers, too.

#

@wispy wharf I'm confused by your question. "...it should also work when it's set to 0 if the force can be big..." How are you expecting that to ever work with a zero? Here's one example (in the manual) of how the engines work (rotation functions on torque, but the basics apply):

force = PositionSpring * (target position - position) + PositionDamper * (targetVelocity - velocity)

So if spring and damper are zero, no force applies.

" The problem with setting the position spring to a high value like this is that gravity is ignored, i.e. holding a pose requires no force whatsoever for the agent, just going to that position requires some."

I can't make much sense of this. If the anchor is null or otherwise fixed and the force is high, then yeah, gravity becomes minor. Holding a pose with a strong spring IS applying a lot of force against any change to that pose.

obsidian geode Jul 4, 2019, 8:47 PM

#

@sly violet teleporting in the concave version is a good idea, thanks!

#

actually, how fast does a collision trigger? is it on every fixedupdate presumably, or will it check immediately when a collider is enabled? if so i could probably have both colliders on the same object and just switch which one is enabled to check the collision

wispy wharf Jul 4, 2019, 8:52 PM

#

@sly violet oh thanks, but when I check how much force is applied to a rigid body when it's holding a pose, then the function only gives me the value for gravity*mass but not the force to hold the pose

#

Also why does position spring need to be something like 5000 for it to work?

#

Can you also send me the reference to the manual?

sly violet Jul 4, 2019, 8:56 PM

#

@obsidian geode : You can't have a non-convex mesh collider on a rigidbody. Collisions are normally checked one per FixedUpdate, but you can get around that with casts - maybe place the collider, run Physics.SyncTransforms, and then run a raycast or spherecast from the projectile.

obsidian geode Jul 4, 2019, 8:58 PM

#

you can if its kinematic, i believe it will still trigger collisions, just not update the parent transform

sly violet Jul 4, 2019, 9:00 PM

#

@wispy wharf "when I check how much force is applied" What are you using to do this?

Spring values tend to be high-ish because they're multiplied by the distance, so if you want a spring to still be applying significant force when you're near the target position, it's getting multiplied by a small number. You can set a lower max so it doesn't go crazy when pulled apart.

Here's the manual page. The section I'm referencing is "Drive forces" near the bottom.
https://docs.unity3d.com/Manual/class-ConfigurableJoint.html

#

@obsidian geode
https://docs.unity3d.com/Manual/class-MeshCollider.html

📎 unknown.png

obsidian geode Jul 4, 2019, 9:03 PM

#

huh, weird, thats not what the editor tells me

#

it says non-convex are deprecated for use with non-kinematic rigidbodies since version whatever

#

📎 unknown.png

sly violet Jul 4, 2019, 9:06 PM

#

What version are you using?

obsidian geode Jul 4, 2019, 9:06 PM

#

2019 1.8f

sly violet Jul 4, 2019, 9:07 PM

#

Seems like it's been this way since at least v2017.1.

wispy wharf Jul 4, 2019, 9:10 PM

#

@sly violet I use joint.currentForce to check it

#

Oh no wait

obsidian geode Jul 4, 2019, 9:11 PM

#

the documentation must be wrong then, because it definitely does work with a kinematic rigidbody

#

the description as per this page https://docs.unity3d.com/ScriptReference/Rigidbody-isKinematic.html seems to be correct

#

not that it helps me 😃

sly violet Jul 4, 2019, 9:12 PM

#

I don't see anything on that page about mesh colliders, convex or otherwise.

obsidian geode Jul 4, 2019, 9:17 PM

#

fair enough, i meant that the behaviour im getting is consistent with that description of a kinematic rigidbody so as far as that goes it seems right

wispy wharf Jul 4, 2019, 9:18 PM

#

Yes, I'm using joint.currentForce

obsidian geode Jul 4, 2019, 9:18 PM

#

but i also definitely do get correct collisions between non-kinematic convex mesh colliders and a kinematic concave mesh collider

wispy wharf Jul 4, 2019, 9:18 PM

#

And if I use joint.currentTorque it's just 0,0,0

obsidian geode Jul 4, 2019, 9:19 PM

#

and the editor leads me to believe thats the expected behaviour, so, the documentation is wrong as far as i can tell

sly violet Jul 4, 2019, 9:20 PM

#

Well, "not supported" isn't always the same thing as "doesn't work". 😉

#

@wispy wharf Two possibilities I can think of: (1), the force required to hold the position is just falling below what's being reported or (2) the "spring" engine isn't actually part of the "solver" at all., and isn't factored into those values. I'm not clear on how those functions work. Are they reporting high values when you're out of position?

obsidian geode Jul 4, 2019, 9:22 PM

#

agreed. the editor is specifically saying that its not supported with a non-kinematic rigidbody though

#

well, it doesnt matter for my use case anyway. just a sidenote

wispy wharf Jul 4, 2019, 9:25 PM

#

@sly violet they're high when I'm moving towards the position but as soon as I reach it they become close to zero and only the force of gravity is printed out

#

I.e. physics.gravity * object.mass

#

Could it maybe be because I'm using slerp drive?

#

The currentTorque also only changes when it moves towards the position but when it's there and holding it it's 0,0,0

sly violet Jul 4, 2019, 10:16 PM

#

Wait... It's holding position, against gravity, using an equivalent force to gravity? That makes perfect sense, doesn't it? If it were using any more or less, it would no longer remain in the target position, right? @wispy wharf

obsidian geode Jul 4, 2019, 10:24 PM

#

in case anyone is keen to know; i 'solved' it by raycasting in front of the projectiles, disabling their collision checking when theyre about to hit a low res collider and then manually tracking the projectiles, toggling low/high res colliders and raycasting toward the high res colliders on fixedupdates

#

it.. works. i wouldnt exactly call it elegant

#

thought about doing it with triggers but it seemed like a chore to set up different layers for props and real colliders etc. whatever else this is, at least its drop-in

wispy wharf Jul 4, 2019, 11:25 PM

#

@sly violet well, to me that would only make sense if the arm was held in the opposite direction of gravity, i.e. when holding the 180deg from the ground. but the force vector is always (0, -gravity*mass, 0), even when I am holding the target position down or to the front... note that the number at the Y position in the vector is positive.. so it is the opposite direction of gravity but it doesnt make sense when you hold the arm down

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if I want the arm just to hang down it shouldn't need any force then... and if the currentForce vector is supposed to be gravity + whatever other force to get to a position, then the force for holding your arm up should be higher

sly violet Jul 5, 2019, 12:48 AM

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It's the total force the joint is exerting. If the object isn't moving, and it's not resting on or jointed to another body holding it up, then it absolutely must be negative gravity no matter how it's arranged.

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Otherwise, it would move.

wispy wharf Jul 5, 2019, 1:15 AM

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Well, it is jointed to another body (a fixed rigidbody which is supposed to be the shoulder) which is holding it up

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@sly violet

wispy wharf Jul 5, 2019, 1:58 AM

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Do you actually know how the maximum force is calculated into this? Because when I set it to 0, it cannot hold it's position anymore but the currentForce vector stays the same

sly violet Jul 5, 2019, 2:29 AM

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If you set maximum force to zero, the "spring" doesn't do anything, but the joint will still hold. currentForce and currentTorque apparently include all forces applied by the joint.

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Keep in mind that the basic constraints of the joint are enforced through forces.

wispy wharf Jul 5, 2019, 1:32 PM

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Ok but my problem with this is that I want the agent to have an incentive to use as little force/torque as possible, e.g. for it being able to rest and hold its arm down when there is nothing to do. If I get the same force for holding the arm up and letting the arm hang, then there is no incentive for the agent to let it hang when it can just keep it up and wait for the next pointing task..... and joint.currentTorque also just returns (0, 0, 0) all the time, which is not right, is it?

sly violet Jul 5, 2019, 4:48 PM

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I think the fundamental problem there is that you're trying to use the current* functions to get at what the spring is doing but they actually return what the entire joint is doing.
Maybe just write your own spring function. It's not a particularly complicated equation, and you can tune it to get the exact results you want and query any part of it you want.

autumn jetty Jul 5, 2019, 7:55 PM

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I'm using the new physics system, and trying to combine it with the networking system. For statics it works fine. But for dynamics it seems that the translation I get from ExportPhysics world is NaN, but it seems the one added on BuildPhysicsWorld is valid. Anyone who could take a guess what is going on?

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There doesn't seem to be anything running in between that shouldn't...

📎 unknown.png

autumn jetty Jul 5, 2019, 9:05 PM

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It's weird cause "world.DynamicBodies[i].WorldFromBody.pos" provides the correct position after ExportPhysicsWorld, but not the translation of the entity that represents it.
Solved: I hadn't set the rotation when spawning it on server, so a quaternion with 0, 0, 0, 0 was used and caused NaN values

unborn narwhal Jul 6, 2019, 3:41 PM

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Anyone uses wolfram alpha? Having trouble understanding what the hashtag symbol is supposed to mean, can't find any info online. https://i.imgur.com/m3RoCW8.png

Imgur

stuck bay Jul 7, 2019, 2:28 AM

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So I have a problem I know is solved in Unity somehow, I have an object going in the way of a sliding door, the object doesn't actually have collision and is move purely by setting the position, how can I move the object out of the path of the door and prevent clipping?

cursive drum Jul 7, 2019, 9:46 AM

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what kind of object

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i'm struggling to imagine this situation

left obsidian Jul 7, 2019, 6:41 PM

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Hey everyone, can someone help me with a collider question? Right now I have a player object, which is a simple box collider, and some box GameObjects. On the box object, I have a collider and a rigidbody, and the boxes have a child with a collider, that is a trigger. So what I expect to happen, is that the player can collide with the object, and move it as it would be able to normally, however, what actually happens, is that it seems to use the non-trigger, and the trigger interchangeably, causing this: https://gyazo.com/7f1c19f3842d7ee89b77d0c1308a22b2 to happen... Anyone who might have an idea why, or is able to tell me if it should be done another way?

Gyazo

▶ Play video

frigid pier Jul 7, 2019, 6:45 PM

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For collisions to properly work you need to move rigidbody using AddForce or MovePosition. The last one may have unexpected effect on other objects you interact with.

left obsidian Jul 7, 2019, 6:47 PM

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Hmm, since the player doesn't have a rigidbody, would moving the player with transform.Translate be sufficient? (Right now I am moving it just by saying transform.position += moveVector, which, seen in hindsight, probably cause a lot of issues)

frigid pier Jul 7, 2019, 6:48 PM

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If you don't use build in physics components, you'll have to create your own physics.

left obsidian Jul 7, 2019, 6:48 PM

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Hmm.. Seems like it's still only working 50% of the time

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Well, I just didn't want to move the player with force necessarily.. But do I have to do that, to ensure that the physics match up properly?

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(By the way, thanks a lot for answering me!)

frigid pier Jul 7, 2019, 6:52 PM

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You can use MovePosition instead, it is close to what you are doing now, sets rigidbody position no matter what interferes. Then physics resolve overlapping colliders pushing them away. In small scale it may work ok. But if object you are pushing gets jammed, for example, between some static collider, it can shoot away unexpectedly in any direction it can.

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Forces behave much more naturally.

left obsidian Jul 7, 2019, 6:53 PM

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Guess I'll rewrite my player with a rigidbody then! Thanks a lot! 😃

frigid pier Jul 7, 2019, 6:54 PM

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You can set very high drag and/or friction, and use strong force to push the player it will move and stop almost instantaneously. You may have to adjust them for corner cases, if you are jumping, etc.

left obsidian Jul 7, 2019, 6:55 PM

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Right now it's only for movement on the xz plane, so should be fairly simple

undone iris Jul 7, 2019, 7:04 PM

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I think this might fit in the physics channel, but I'm not sure, I am having a bit of trouble with the rigidbody, basically, I know you can add velocity, by using this piece of code transform.GetComponent<Rigidbody>().velocity += new Vector3(0,0,-speed); and also, I want it to hop up a bit when it moves, so I put transform.GetComponent<Rigidbody>().velocity += new Vector3(0,upSpeed,-speed);, however, I have a problem, I don't know how to make it precise, for example, if i put the upSpeed to be 1, and speed to be 5, and then when I calculate the distance of how much the object moved, it's something like 0.8948889 and the worst part is, it's not always 100% consistent! so in conclusion I was wondering if it's possible to set a value, like 3 for example, and then, based on that value, somehow calculate how much velocity I would need to apply in order for the rigidbody to move that distance.

craggy peak Jul 8, 2019, 4:33 PM

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Hi People !! Can anyone help me with my tennis ball physics ? I have the code and It works, but I want to upgrade so it looks better

plain obsidian Jul 8, 2019, 8:37 PM

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So im having a problem with the jumping of my character... Basically he teleports up and glides down instead of jumping normally

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Does anyone know whats the possible cause for this behaviour?

narrow quiver Jul 8, 2019, 9:50 PM

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@undone iris quite possibly you have a linear drag coefficient, gravity and such set for the rigidbody. Without drag you should be able to calculate height with:

h,max = upspeed*upspeed/(2*Physics.gravity.magnitude)

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e.g if you want to achieve h,max = h, you can calculate it as:

upspeed = Mathf.sqrt(2 * h * Physics.gravity.magnitude)

quartz wyvern Jul 9, 2019, 5:59 AM

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is there a way to have a collider collide into another without applying the force upon impact

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but they will still collide

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i cant use kinematic because they still use general physics

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but i dont want them to recieve impact forces

narrow quiver Jul 9, 2019, 11:13 AM

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you could cast rays every tick from last position to new position, and translate the object to the impact point of the ray whenever it reports collision

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@quartz wyvern

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that's assuming you want neither of them moving

sly violet Jul 9, 2019, 5:24 PM

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@quartz wyvern : You may need to elaborate, because as stated the request doesn't make any sense - if there's no impact force, then there's no collision (and they'll go right through each other). If you don't want them to go through each other, but you don't want normal collision behavior, there's a number options, but it'll depend heavily on what you're really trying to achieve.
Examples:

Just set the bounciness to zero. Then, they won't bounce off each other.
One of them should be totally unaffected by the collision, but the other is affected normally. The easiest way to do this is just have the heavier object be much heavier, but if you need a more absolute solution, you can have a kinematic object following the "heavy" object, and the "light" object only interacts with this kinematic shadow.
You can run a sweep from each object each frame and just stop them outright when they're about to collide, so they never collide as far as the physics are concerned.

quartz wyvern Jul 9, 2019, 7:33 PM

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@sly violet basically 2 is the ideal one but i can't change their masses because it will effect how they work in water simulations

sly violet Jul 9, 2019, 8:02 PM

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So maybe try the "kinematic shadow" solution: create another kinematic Rigidbody in the same position as the heavy object (updated every FixedUpdate). Use Layers and/or specific ignore to make sure the kinematic body collides with the smaller body, not the heavy body, and others as desired.

quartz wyvern Jul 9, 2019, 8:49 PM

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hmm i see

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sounds messy but ill try it

iron pagoda Jul 9, 2019, 9:14 PM

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on collision enter set the rb kinematic on then off, it'll reset the forces

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well, zero out the forces

sly violet Jul 10, 2019, 4:40 PM

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You can do that just by setting rb.velocity=0f, but it's rarely an ideal solution; for example, it won't work in this case, because the smaller object will have already impacted the larger object, and Sir wants the larger object to be unaffected.

stuck bay Jul 11, 2019, 10:16 AM

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Hey guys, i have a sphere with a costant velocity and want to boost it sometimes but addforce just transports it higher without interpolation

sly violet Jul 11, 2019, 2:49 PM

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If you want to accelerate it over a period of time, you call AddForce every FixedUpdate during that period of time.

mighty sluice Jul 11, 2019, 11:41 PM

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So I need to make some meshes for unity to make sure they are at correct scale, any suggestions with regard to which third party program to use?

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or otherwise, is there any way that i can reshape existing meshes and ensure that they are exactly the scale I need?

hollow echo Jul 11, 2019, 11:52 PM

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1 unit is 1m in unity. If you do the same in your modelling program then if the import is scaled incorrectly you can always change the import scale setting with a simple value

mighty sluice Jul 12, 2019, 12:41 AM

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so do i need to worry about how i rescale primitive shapes like spheres and capsules?

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in other words, does rescaling the primitive collider correctly rescale it for the physics engine?

mighty sluice Jul 12, 2019, 2:37 AM

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I guess im wondering if the primitive colliders are like,dynamically sized meshes

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because apparently the mesh scale on import will affect physics stuff, but the primitive collider isn't even really a mesh,s o im not sure if I should notworry about it and just set material properties

mighty sluice Jul 12, 2019, 3:18 AM

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i'm basically looking to get really good rigidity in a joint connected body

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, where projection mode wont suffice

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(too many connected parts)

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trouble is no matter the scale, there always seems to be some wobbliness in the joints, which creates undesirable ramifications for the body (instability)

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so far the best solution i have found is to make a wireframe of game objects and joints that have very high mass but no gravity

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and then to attatch "weight" objects to them via fixed joints

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if anyone has ideas for a more appropriate solution, I would very much appreciate it

stuck bay Jul 12, 2019, 9:07 AM

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anyone in?

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thanks @sly violet i did it

stuck bay Jul 12, 2019, 10:02 AM

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I try to make a sphere move with rb.moveposition() and jump with addforce() but when i move it on air it jitters

mighty sluice Jul 12, 2019, 8:40 PM

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@stuck bay that might be vibrations caused by "drag" setting on the rigidbody

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you can make it very small, or zero, but be aware that this might cause an infinite "terminal velocity" when the object is falling

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i think having a very small setting as opposed to zero helps with stability in come conditions, but im not experienced enough to give you a definitive answer

stuck bay Jul 12, 2019, 8:49 PM

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@mighty sluice i fixed it Chris, i should put the code in FixedUpdate

mighty sluice Jul 12, 2019, 8:49 PM

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ah, yea that makes sense

stuck bay Jul 13, 2019, 6:56 AM

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How can i attack an object on a cloth?

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attach*

narrow quiver Jul 13, 2019, 11:17 AM

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Attach an empty named gameobject as child to part of the cloth (if its kinda stationary) or have an empty named element in the prefab and set the object parent, position and rotation to that of the named element.

mighty sluice Jul 13, 2019, 11:58 AM

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So I think my issues might be in part caused by unrealistic inertia tensors (not Unity's fault)

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I'm trying to simulate a spider, and their legs are extremely tiny, but also extremely robust for their mass

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A part of the problem i'm having comes from momentum forces,which im hoping is sanely modeled via the inertia tensors

mighty sluice Jul 13, 2019, 9:24 PM

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after some initial testing of the inertia tensor, it looks like most of my issues did result from wonky shaped tensors

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im using capsule colliders that are massively stretched so the inertia tensor was like 15, 0.1, 15

mighty sluice Jul 13, 2019, 10:11 PM

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for whatever reason, i can find almost no resources about intertia tensor

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is it just really specific and complex? trade secrets ? 😄

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glancing at the math, it's definitely super complex to calculate yourself, but it doesnt seem too crazy to think about the tensor itself...

sly violet Jul 13, 2019, 10:18 PM

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Basically it tells the physics system the relation between torque and angular velocity at various, um, vectors of turning. It's normal for an elongated object to be "easy" (low torque for a given angular velocity) to spin across it's long axis and "hard" to spin it lengthwise. So that tensor looks about right - low in one axis, high in the other two.

mighty sluice Jul 13, 2019, 10:28 PM

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ah yes, but the ratio then can lead to issues

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when you have 4 long connected segments, for example, and alltheir tensors are wacky like that

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the result is the side to side motion of the end piece has so much momentum that it breaks the joint limits completely

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it's like trying to hold up a long heavy pole from one end instead of the middle

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i do understand the concept, but more information about how it relates to unity physics would be useful

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for example, somehow both the mass and inertia tensor work together to affect joint rigidity

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i would like to know exactly how,

inner cloud Jul 14, 2019, 7:20 PM

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how do you move a rigidbody without the collision breaking before your very eyes

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?

quartz wyvern Jul 15, 2019, 6:14 AM

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define breaking

lapis plaza Jul 15, 2019, 9:44 AM

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by not moving the rigidbody manually

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use forces to move it

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if your code manually moves rigidbody to be inside other rigidbody, things can break

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so that's on you 😃

mossy mirage Jul 15, 2019, 4:27 PM

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Howdy guys, I’m curious if any of you guys know if Scenes in unity run in the same 3D space and/or have the same physics processor? I’m looking at possibly moving to Unity and it’s relevant to network instancing. Please @ me back. Thx.

lapis plaza Jul 15, 2019, 4:43 PM

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@mossy mirage there's no separate physics scene in normal Unity physics if you ask about that

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well, kinda

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but each additively loaded scene can have their own 3d physics scene which you can simulate separately

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it's relatively little known feat Unity added in 2018.3

mossy mirage Jul 15, 2019, 4:45 PM

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that is fantastic

lapis plaza Jul 15, 2019, 4:45 PM

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if you need more indepth explanation in finnish, you can DM me as this group is for english only

mossy mirage Jul 15, 2019, 4:45 PM

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when you say "additively loaded" is that something peculiar to Unity.. not just a separate scene?

lapis plaza Jul 15, 2019, 4:46 PM

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it's a separate scene alright 😃