#⚛️┃physics | Official Unity Discord | Page 55

undone lynx Jul 23, 2020, 2:33 PM

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if u directly set the velocity itd be constant

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u can add gravity in that same set

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try the constantforce thingy too btw

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maybe simpler

unreal linden Jul 23, 2020, 3:18 PM

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Stresstest of my realtime Destruction system, 22 Million vertices on a 250 meter (820,25 feet) bridge.

📎 stresstest.mp4

torpid prism Jul 23, 2020, 5:23 PM

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@unreal linden is this baked ?

unreal linden Jul 23, 2020, 5:24 PM

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@torpid prism What part of it ?

torpid prism Jul 23, 2020, 5:24 PM

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lol everything

unreal linden Jul 23, 2020, 5:24 PM

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The fracturing ?

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No

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only the fracturing

torpid prism Jul 23, 2020, 5:24 PM

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ah i see

unreal linden Jul 23, 2020, 5:24 PM

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I do have a dynamic fracturing system wich baked this, but it couldn't run in realtime of a bridge this massive

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Physics are realtime

torpid prism Jul 23, 2020, 5:25 PM

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is this ECS physics ?

unreal linden Jul 23, 2020, 5:25 PM

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Nope

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Old standard non-ECS physics

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Running on the CPU aswell atm

torpid prism Jul 23, 2020, 5:25 PM

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impressive body count

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what rig do u have /

unreal linden Jul 23, 2020, 5:26 PM

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Ryzen 7 2700X

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RTX 2060

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Its about 2000 pieces

torpid prism Jul 23, 2020, 5:26 PM

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good gear

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you called it a fracturing system

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does it scans the vertices of the mesh

unreal linden Jul 23, 2020, 5:27 PM

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Nope, it just does a voronoi

torpid prism Jul 23, 2020, 5:28 PM

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so u divide the points into voronoi regions ?

unreal linden Jul 23, 2020, 5:28 PM

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I am experimenting with Houdini tho for better fracturing

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yeah, it just scatter voronoi points evenly

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then breaks it

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and then iterates on it

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And fractures it again

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4 iterations on that Bridge

torpid prism Jul 23, 2020, 5:29 PM

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neat

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realtime fracture would be very useful

unreal linden Jul 23, 2020, 5:30 PM

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Yeah it can do that

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But not a Bridge that huge

undone lynx Jul 23, 2020, 7:35 PM

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very cool @unreal linden

unreal linden Jul 23, 2020, 7:35 PM

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Thanks !

undone lynx Jul 23, 2020, 7:39 PM

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is it running at the default physics tick rate?

unreal linden Jul 23, 2020, 7:45 PM

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Yes, but at only 2 iterations.

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Plus some other trickery

undone lynx Jul 23, 2020, 8:03 PM

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it looks well optimized rn considering the level of detail

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i imagine u could run it at like half tickrate and get okay results

sour lark Jul 23, 2020, 8:20 PM

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Hello there i never had this problem but now the physics in 2D are getting annoying! In my editor I can play the game and set the rigidbody2D velocity to like 50. In the build the object with the velocity applied moves a lot faster than in the editor. The Canvas also scales different and the position isnt the same aswell. Even if I set the canvas scaler to fit with screen size. Can anyone help me out with this 2 problems

unreal linden Jul 23, 2020, 8:28 PM

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i imagine u could run it at like half tickrate and get okay results
@undone lynx Yeah, or set the iterations to 1 or use less pieces.

foggy rapids Jul 23, 2020, 8:53 PM

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FixedUpdate is what makes your physics smooth on various devices. Release builds get higher frame rate and if there is movement code in Update() it's gonna get wacky.
The other problem is screen resolution and there are so many ways to deal with that it's a crap shoot.
I would set the camera's orthographic sized based on the width/height of the screen but i forgot the math

livid skiff Jul 23, 2020, 9:22 PM

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Are there any "good" solutions to rigidbody character controllers "tripping" over seams between aligned colliders and shooting up into the air? The only real feasible one seems to be lifting the collider off the ground, raycasting, and manually aligning it over the floor but this feels like a hack and a lot of work with regards to managing all the states where I may want to push the character (jumps, getting hit, etc)

undone lynx Jul 23, 2020, 9:23 PM

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i actually do that

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lemme link smth

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an idea

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https://rockhamstercode.tumblr.com/post/177840382888/character-physics-tricks

Tumblr

Realtime Animation Tips & Tricks

Character Physics Tricks

While I haven’t run out of meaty animation topics yet I want to go into a topic that is easily underestimated and that is what is commonly used to move characters around in the worlds that we build. A...

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theres one way u can have a collider off the ground

foggy rapids Jul 23, 2020, 9:24 PM

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the easiest one is to reshape the collider so it doesn't have 90 degree corners dragging on the ground

undone lynx Jul 23, 2020, 9:24 PM

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thats why capsules are most often used for characters

stuck bay Jul 23, 2020, 9:25 PM

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Hmm

livid skiff Jul 23, 2020, 9:25 PM

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Yeah, I'm using a capsule for the character, not a box or anything, so no corners... but it still trips on "perfectly aligned" seams etc

undone lynx Jul 23, 2020, 9:25 PM

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usually theres some code that

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does "step resolving"

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ie stairstep code

stuck bay Jul 23, 2020, 9:25 PM

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@livid skiff is it 2D game ?

undone lynx Jul 23, 2020, 9:26 PM

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so it automatically moves up

foggy rapids Jul 23, 2020, 9:26 PM

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remove the seams is another good solution

livid skiff Jul 23, 2020, 9:26 PM

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Yeah, I haven't gotten to my step resolution yet (been hoping I can get away with ramps, but not sure yet) so not sure if it may just get solved by the same solution but I don't think so

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It's 3D

undone lynx Jul 23, 2020, 9:26 PM

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thats what u proposed originally, code to do the alignment

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btw give that article i linked a whirl

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i use that approach for my rigidbody cc

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to do steps

livid skiff Jul 23, 2020, 9:26 PM

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I can't remove seams because I'm using proc-gen and regenerating colliders at runtime for each configuration of "tiles" would suck

stuck bay Jul 23, 2020, 9:27 PM

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True that

livid skiff Jul 23, 2020, 9:27 PM

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Yeah, still reading through that article - thanks

foggy rapids Jul 23, 2020, 9:27 PM

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nothing is impossible :D
i'm actually going to need to solve that problem soon

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was gonna try marching cubes first

undone lynx Jul 23, 2020, 9:27 PM

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i also think theres some reading for step resolution online, u can look into that too. i think thats the reason ur capsule trips up on the seams

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bc it isnt actually stepping over anything

livid skiff Jul 23, 2020, 9:28 PM

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I've done a lot of reading on step resolution but the solution I'm planning has to do with detecting angles and such that I don't think will "trigger" in these cases, so I feel this will be an independent problem and looking for ideas before I implement either system haaha

undone lynx Jul 23, 2020, 9:33 PM

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📎 2020-07-24_02-33-13.mp4

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heres a little how it looks like in action

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basically just keeping the collider bottom a certain distance away from the ground point at all times

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theres no actual step resolution code this way

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no collision checking

livid skiff Jul 23, 2020, 9:35 PM

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Yeah, it's actually pretty close to the original idea I was trying to avoid, but the spring concept alleviates some of my hesitation etc. It still will require me to "disable" it in cases where I want to push the player, but I think I just have to deal with it... And yeah, if I build this I don't need to deal with stairs...

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I was wondering if there are standard "alternatives" but seems most people use this approach

undone lynx Jul 23, 2020, 9:36 PM

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in my case i dont run the spring unless the character is grounded

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its proven fairly versatile to me, considering the ease of implementation

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easy to tweak when i want a bit different behaviour too

livid skiff Jul 23, 2020, 9:37 PM

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Yeah, I think it makes sense... just trying to weigh all my options before committing but seems like this is the way to go

undone lynx Jul 23, 2020, 9:37 PM

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the thing about concrete step resolution is

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thats extra code

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thats gonna run every collision

livid skiff Jul 23, 2020, 9:37 PM

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The spring is a nice addition though, so thanks for the tip 😉

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yeah...

undone lynx Jul 23, 2020, 9:38 PM

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good luck tho

livid skiff Jul 23, 2020, 9:38 PM

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thanks 🙂

graceful meadow Jul 23, 2020, 10:43 PM

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anyone know how to calculate a jump's initial velocity given jump height, gravity, mass and linear drag?

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i figured out how to do it without the drag but drag is pain
jumpVelocity = Mathf.Sqrt(2f * Physics2D.gravity.magnitude * jumpHeight * body.mass);

dusk token Jul 24, 2020, 3:16 AM

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I'm new to unity, so I'm still getting used to all the moving parts, I've got a 2D rigidbody (player) and an object that I want to be collideable

📎 unknown.png

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📎 unknown.png

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These are my components with the player in the first pic and the object in the second picture

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Unfortunately my OnCollisionEnter2D isn't being called when within the area defined by this object

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Anyone know what I'm doing wrong here?

hollow echo Jul 24, 2020, 3:27 AM

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your collider is marked as trigger

dusk token Jul 24, 2020, 3:30 AM

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Neither should be marked as trigger?

hollow echo Jul 24, 2020, 3:34 AM

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Trigger colliders get OnTriggerEnter messages

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not OnCollisionEnter messages

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if there is a trigger involved in the interaction at all it's not a Collision

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📎 unknown.png

dusk token Jul 24, 2020, 3:39 AM

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Ok awesome, and how can I prevent the camera from rotating? I've got a topdown game and when my square player attempts to enter a U shaped doorway which is too small for it, the whole screen rotates since only the corner of the player can fit in. I want nothing to be rotatable

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All I can find is people complaining about mobile screen orientation unfortunately

willow vortex Jul 24, 2020, 4:05 AM

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don't parent the camera and have a script to move only the camera position to follow the player? ¯_(ツ)_/¯

dusk token Jul 24, 2020, 4:11 AM

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Well I dont want the player rotating either lol

willow vortex Jul 24, 2020, 4:33 AM

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look at rotation constraints in the rigidbody(?), those might work fine, or might glitch you out so horribly that it flungs you into the void xD

dusk token Jul 24, 2020, 4:35 AM

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sweet

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ty y'all

languid obsidian Jul 24, 2020, 11:57 AM

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why am i still colliding with the particles system? i want the particle to act like fog and not get pushed by the player

📎 unknown.png

prisma ingot Jul 24, 2020, 1:02 PM

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Hi so i've started learning unity and i made a code that should make a ball jump and move but when i give a value to salto my ball goes out of the screen flying.
This is the code:

public class move : MonoBehaviour
{

public float forceValue;
public float Salto;
private Rigidbody rigidbody;
void Start()
{
rigidbody = GetComponent<Rigidbody> ();
}

void Update()
{
if (Input.GetButtonDown("Jump") && Mathf.Abs(rigidbody.velocity.y) < 0.01f);
rigidbody.AddForce(Vector3.up * Salto, ForceMode.Impulse);
}

public void FixedUpdate()
{
rigidbody.AddForce(new Vector3 (Input.GetAxis ("Horizontal"),
0,
Input.GetAxis("Vertical")) * forceValue);
}
}

willow vortex Jul 24, 2020, 2:56 PM

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your if() has a ; at the end which means the statement ends there, it doesn't apply the if() to the next line

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VS should've warned you there... are you not using an IDE? 😛

prisma ingot Jul 24, 2020, 3:06 PM

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your if() has a ; at the end which means the statement ends there, it doesn't apply the if() to the next line
@willow vortex thx dude i didnt notice

dusk token Jul 24, 2020, 6:14 PM

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I've got a prefab called "NPC", when I drag it directly into the scene, its movement works fine, but for whatever reason when I Instantiate() one of these NPCs, its RigidBody2D velocity does not update.
My FixedUpdate contains body.velocity = movement * runSpeed;
And body is defined in Awake() as body = GetComponent<Rigidbody2D>();
Anyone know why?

tiny wedge Jul 24, 2020, 10:58 PM

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ok i found a way to collide with an object which has no collider (but has a rigidbody)

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i guess i broke unity

forest flame Jul 25, 2020, 12:03 AM

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Does that rigidbody have a child object with a collider?

lunar magnet Jul 25, 2020, 4:01 AM

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when using joints does it matter which gameobject has the joint componenet and which gameobject is the connected body?

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does it effect anything?

willow vortex Jul 25, 2020, 9:11 AM

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@dusk token did you look at the instantiated object in the inspector after it was spawned? maybe it doesn't have the defaults you expect, like runSpeed = 0 xD

graceful meadow Jul 25, 2020, 11:32 AM

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@lunar magnet physically nope, but if you modify your joints with a script, it's more maintainable to put the joint and script on the same object

little egret Jul 25, 2020, 1:12 PM

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i have an character that carrrys a rigidbody , i move the rigidbody every fixedstep away to a min distance from the character by the nearest mesh point, problem is, as soon as i move, my character detects the collision because the rigidbody haven't move this step, i can't ignore collisions with this rigidbody because when i walk to a wall and it get's stuck i don't wanna walk through it, it should collide. I have no idea how i should detect when to collide and when not without doing very complex collision solving on the rigidbody by myself. Any ideas anyone?

foggy rapids Jul 25, 2020, 2:13 PM

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try attaching it with some kind of joint

little egret Jul 25, 2020, 3:10 PM

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yes that's the next possibility but i don't really like it, because the rigidbody should rotate sometimes :/

foggy rapids Jul 25, 2020, 3:11 PM

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it will be difficult, but you can make a joint that does that

little egret Jul 25, 2020, 3:14 PM

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i have an idea but the problem is always the same, i know before i update the kinematic controller where i want to move him, i could move the rigidbody away, but i have to move it by force because collision detection is important and the kinematic controller isn't by force. I can add the movement to the rigidbody velocity, but i think because the rigidbody will update NEXT fixedupdate the problem will be the same

neat swift Jul 25, 2020, 3:14 PM

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Been having lots of problems detecting collisions lately. Ive tried custom scripts to amplify collision detection beyond its default limits and modified the detection mode, but still, collision only gets detected sometimes while the same simulation takes place. Very frustrating and makes me wonder if my setup is wrong or anything odd like that.

📎 notDetectingCollision.gif

little egret Jul 25, 2020, 3:14 PM

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and moving by setting the position will break collision detection

graceful meadow Jul 25, 2020, 3:14 PM

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check your collision matrix in project settings too

neat swift Jul 25, 2020, 3:15 PM

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The gif is showing 2 colliders where the ball obviously is going through the collider in slow speed while not being detected.

little egret Jul 25, 2020, 3:15 PM

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how do you move it hierkus?

neat swift Jul 25, 2020, 3:15 PM

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I havent modified it. Thing is that it works sometimes and sometimes it doesnt, it shouldnt be like that at all

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I just move it with the mouse in that gif

little egret Jul 25, 2020, 3:16 PM

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no with rigidbody addforce or by setting the position or something

neat swift Jul 25, 2020, 3:17 PM

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Transform.translate. But you can test basic collision detection by using the editor in playmode, and the collision in the GIF above sometimes work and sometimes doesnt. It should be consistant

little egret Jul 25, 2020, 3:17 PM

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that never works

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use force

foggy rapids Jul 25, 2020, 3:17 PM

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well you could just always move both rigidbodies at the same time and always move the attached one first

neat swift Jul 25, 2020, 3:17 PM

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What?

little egret Jul 25, 2020, 3:17 PM

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MICKEN its no rigidbody , the character

graceful meadow Jul 25, 2020, 3:17 PM

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make sure both rigidbodies are either kinematic or dynamic too

neat swift Jul 25, 2020, 3:18 PM

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The ring has a rigidbody

graceful meadow Jul 25, 2020, 3:18 PM

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static ones dont receive collision callbacks

foggy rapids Jul 25, 2020, 3:18 PM

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doesnt matter what they are.

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@neat swift collisions arent detected when you drag things around in the scene view afaik

little egret Jul 25, 2020, 3:18 PM

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hierkus 2 rigidbodys, set on continous collision detection and use force to push it through, im pretty sure it will accurately detect collisions

neat swift Jul 25, 2020, 3:19 PM

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They do for my editor, ive done that many times while testing

little egret Jul 25, 2020, 3:19 PM

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@foggy rapids maybe i'm missunderstand, if i move the kinematic by settings the position, it will be instant, but the force is not instant

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that's the problem with it

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i set the velocity, but that updates the rigidbody in the next fixedupdate, the character updates in the same, if i know a way to fix that, it would be easy

neat swift Jul 25, 2020, 3:20 PM

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Only the ring has a rigidbody, but ball and ring has a collider so they should work according to Unity's matrix collision

foggy rapids Jul 25, 2020, 3:20 PM

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whatever it is you do, always do it at the same time and always to the one you care about first

neat swift Jul 25, 2020, 3:21 PM

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What do you mean Micken?

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Provide an example of how i could do it

little egret Jul 25, 2020, 3:22 PM

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but how? i know no way to do it in the same fixedupdate without breaking the collision detection. What did i miss? @foggy rapids

dusk token Jul 25, 2020, 3:24 PM

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@willow vortex I ended up just not using instantiation. After the things were created the velocity seemed locked to 0 even though it was definitely being assigned to with a value greater than 0

foggy rapids Jul 25, 2020, 3:24 PM

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dont put it in fixedupdate, call it from some other script's fixedupdate

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in the order you choose

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@neat swift press play?

little egret Jul 25, 2020, 3:41 PM

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@foggy rapids sry if i don't understand maybe i missed that part, but what does it change to do it from another script ? The transform of the character will be moved with SetPositionAndRotation, the item that he carrys will get an rb.velocity = newvelocity, doesn't that mean: the character moves instant but the rigidbody will move NEXT fixed update? Is that wrong ? If yes i should try again and search for another error i made, because i already tried that.

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to explain better maybe: first the function to add set the velocity will be called, but in this fixedupdate he will stay on his position (?right) and then the SetPositionAndRotation gets called and trys to move but the "old" position of the rb will be still in his way and will stop him.

neat swift Jul 25, 2020, 4:15 PM

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So i found out that collisions work, but not nearly as precise when using trigger mode. Only works every 3-4nth collision.

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Is there anything you need to keep in mind when using trigger? Its weird how non-trigger collision detection works 100% but only ~50% with trigger

little egret Jul 25, 2020, 4:28 PM

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moving triggers need a rigidbody

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set it to kinematic

fresh grail Jul 25, 2020, 6:17 PM

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now unity gives me option to fling my object in some dirrection or to not move it all. How do i get a nice acceleration between the 2? Applying forces doesnt work, because its unity we are talking about.

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https://www.youtube.com/watch?v=8OUGXBd99w4

YouTube

DageLV

2020 07 25 20 44 59

▶ Play video

neat swift Jul 25, 2020, 7:06 PM

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@fresh grail What is the question?

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@little egret All moving triggers have rigidbody

fresh grail Jul 25, 2020, 7:06 PM

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if i apply 8.2 acceleration, how do i accelerate the object by 8.2

neat swift Jul 25, 2020, 7:07 PM

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Set the forcemode Enum to Acceleration

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Then stop it when your desired velocity is achieved

fresh grail Jul 25, 2020, 7:08 PM

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i suspect you did not watch the video

neat swift Jul 25, 2020, 7:08 PM

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The video is 8 min long

fresh grail Jul 25, 2020, 7:08 PM

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and you didnt watch it for even a minute

neat swift Jul 25, 2020, 7:08 PM

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If you can formulate the question clearly, there is no need to watch a 8 min video lol

fresh grail Jul 25, 2020, 7:09 PM

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i apply 31 force. Object doesnt move. I apply 31.2 force, the object flies in the dirrection.

neat swift Jul 25, 2020, 7:13 PM

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Normally, it should move when force is applied, but you also need to consider the mass of the object you are applying force too. BUt i assume the mass isnt a problem since it "flies" like you say, when you apply just a little bit more force to it

fresh grail Jul 25, 2020, 7:13 PM

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the mass is 1000 and force is applied at 10 locations

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there are 5 wheels on each side.

neat swift Jul 25, 2020, 7:15 PM

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Maybe you have something in the script that is causing it? I dont know

fresh grail Jul 25, 2020, 7:16 PM

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thisRigidbody.AddForceAtPosition(transform.forward * power, transform.position, ForceMode.Acceleration);
``` thats all there is to the script.

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power is 30 and object doesnt move. if its 40, it flies etc

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if the forceMode is .force i have to apply like 8 thousand force at the 10 locations to move it

neat swift Jul 25, 2020, 7:18 PM

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That's the velocity required to move the mass

fresh grail Jul 25, 2020, 7:18 PM

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yeah

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and still. With 8.2 acceleration it doesnt move.

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I get it to move initially, then switch back to 8.2 and it kinda works

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it can stop to 8 and immediatelly change its dirrection and still move in that velocity

neat swift Jul 25, 2020, 7:20 PM

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And you should multiply the velocity with time.deltatime to make sure it cover the desired velocity regardless of change in FPS

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Unless you apply force in fixedupdate

fresh grail Jul 25, 2020, 7:20 PM

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first i need it to move tho

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it is in fixedUpdate

neat swift Jul 25, 2020, 7:22 PM

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Maybe you need to be even more specific with the acceleration rate

fresh grail Jul 25, 2020, 7:23 PM

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i need it to accelerate at whatever speed i set it to. be it 0.5 m/s or 50 m/s. unity cant even move 31 force and it throws the object at 31.2

rocky cave Jul 25, 2020, 11:25 PM

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How do i make a function that moves a gameobject slowly from one spot to another?
all i have found is how to do it inide void update but i want a function

willow vortex Jul 26, 2020, 3:51 AM

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@rocky cave coroutines? I dunno what you're looking for, Update() is a function too ¯_(ツ)_/¯

frank juniper Jul 26, 2020, 3:58 AM

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How do I coordinate the rotation of the z axis of one object with the y axis of another?

shut wind Jul 26, 2020, 3:59 AM

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What would be the best way to update a colliders mesh continuously? I've got some code that deforms a plane when an object collides, but when i try to update the colliders vertices it becomes extremely slow. Any ideas?

willow vortex Jul 26, 2020, 4:25 AM

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@frank juniper probably something like this? cs float otherY = other.rotation.eulerAngles.y; transform.rotation = Quaternion.Euler(otherY, 0, 0);
or maybe localRotation would be better ¯_(ツ)_/¯

frank juniper Jul 26, 2020, 4:26 AM

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I'll try it out thanks!!

stuck bay Jul 26, 2020, 4:41 AM

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is there any way i could simulate a 4d object in unity 3d?

narrow relic Jul 26, 2020, 5:41 AM

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can someone tell me why this is happening? my coins are falling through the floor in the game but show up that they aren't in scene view.

📎 2d_project_-_tutorial_-_PC_Mac__Linux_Standalone_-_Unity_2019.3.9f1_Personal___DX11__2020-07-26_01-3.zip

willow vortex Jul 26, 2020, 6:02 AM

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they seem to dive even more on the lower platform, what the heck 😆

narrow relic Jul 26, 2020, 6:34 AM

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ik right so wierd

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but when i check scene view they show up were they should be

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and there collision boxes are also were they should be in game

willow vortex Jul 26, 2020, 8:15 AM

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when you make one appear can you pause the game and select a coin in the hierarchy so you can see its collider outline 🤔

languid hull Jul 26, 2020, 12:32 PM

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how to do a 2 way joint

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where both are treated as equal

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each move to maintain distance

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not just one of them as anchor

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but they affect each other

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Do I just attach them to each other

fallow chasm Jul 26, 2020, 5:15 PM

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for some reason this line of code is causing a compiler error and idk why

float fX = fMovementSpeed * (float)Math.Cos(rotation)

willow vortex Jul 26, 2020, 5:39 PM

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missing ; at the end? you didn't post the error so one can only guess, and this is more of a #💻┃code-beginner question btw 😛

fallow chasm Jul 26, 2020, 6:16 PM

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the original code does have ;, I just forgot it when i copied and pasted it. and im not getting an error message, the only thing unity is telling me is "No amonoBehaviour scripts in the file, or their names do not match the file", but that can't be the problem because it works when I comment out that line

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also sorry if this is the wrong channel, I just assumed that because this line was going to be used to make a vector 3 it belonged here

graceful meadow Jul 26, 2020, 6:20 PM

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@fallow chasm can you please link the entire class?

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and it's more common practice to use UnityEngine.Mathf instead of System.Math

fallow chasm Jul 26, 2020, 6:26 PM

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it started working once I switch to Mathf, ty : )
I can still send you the class if you want

graceful meadow Jul 26, 2020, 6:27 PM

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ayy nice! and im good heh

narrow relic Jul 26, 2020, 7:10 PM

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@willow vortex i paused it and when paused they showed above ground. im so confused

sleek storm Jul 26, 2020, 10:16 PM

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Does anyone have a suggestion on how to make a game object go in the opposite direction from where it collided with an object? Working with Rigidbody2D. I have the collision events written I'm just not sure what force or even how best to apply it.

foggy rapids Jul 26, 2020, 10:22 PM

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never tried it myself, but i would guess that the inverse of collision2d.relativeVelocity might suit your purposes

sleek storm Jul 26, 2020, 10:22 PM

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Thinking about it a bit more what I'm most having trouble with is how to detect the collision vector to reverse it in the first place.

foggy rapids Jul 26, 2020, 10:23 PM

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you might also try with the material's bounciness property

sleek storm Jul 26, 2020, 10:24 PM

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Oh, I didn't think about that, might be an easy way to handle this.

foggy rapids Jul 26, 2020, 10:24 PM

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from my experience with bounciness it's easy to get almost right, but nearly impossible to get perfectly right

sleek storm Jul 26, 2020, 10:25 PM

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Eh, just a weekend game jam, I'm not so worried about perfect lol

#

Thanks for the suggestions!

#

Bouncy material worked great

foggy rapids Jul 26, 2020, 10:37 PM

#

🎉

burnt imp Jul 27, 2020, 6:48 AM

#

📎 unknown.png

#

anyone have any thoughts on how i would calculate this?

severe bay Jul 27, 2020, 6:54 AM

#

Is new velocity just some x axis only value?

burnt imp Jul 27, 2020, 6:54 AM

#

no no. sorry assume all in vector3s

severe bay Jul 27, 2020, 6:55 AM

#

I mean in the example its horizontal. Is it always horizontal?

burnt imp Jul 27, 2020, 6:55 AM

#

honestly. i just need the direction of the "new velocity" i should be expecting

#

most likely... i guess not always huh.. im trying to figure out a grapple hook system where it would just swing my character around as they're falling

#

but i dont want to do it like. widowmaker's where it just

#

moves them to the target

severe bay Jul 27, 2020, 6:56 AM

#

Why not just get a normalized vector thats the length of the grapple and move them based on their velocity prior to normalizing it?

burnt imp Jul 27, 2020, 6:56 AM

#

i also dont need to accomodate for multiple periods. i think ill just apply the new velocity based on the "pendulum" for 1 period and then deattach

#

sorry can i DM you? i dont want to flood this channel

severe bay Jul 27, 2020, 6:57 AM

#

I think the whole point of the channel is for this stuff lol

burnt imp Jul 27, 2020, 6:57 AM

#

lol fair.. i just feel bad. feel ike im spamming it

#

but um. what would a normalized vector

#

of the length yield?

severe bay Jul 27, 2020, 6:58 AM

#

let me draw something real fast

burnt imp Jul 27, 2020, 6:58 AM

#

kk

#

sorry i havent done physics since taking it 8 years ago in college so im super rusty at it. really appreciate the ideas

severe bay Jul 27, 2020, 7:04 AM

#

📎 unknown.png

#

So in step 1, everything is set up, the player is moving based on their velocity

#

step 2, their velocity moves then farther than the rope. The rope is 5 units, but now the player is 6 units away

#

step three, you normalize the vector between them (make it have a length of one, then multiply by the length of the rope), and now they're in the right spot

#

which in unity is just myVec.normalized

burnt imp Jul 27, 2020, 7:07 AM

#

sorry what do you mean by. "normalize the vector between them"

#

so do i subtract the grapply hook position and the player pos?

severe bay Jul 27, 2020, 7:08 AM

#

So just rope.transform.position - transform.position or visa versa depending on how you're doing it

burnt imp Jul 27, 2020, 7:09 AM

#

so im basically calculating for

#

📎 angles2.png

#

the B? i guess?

i guess the easiest way would be to just grab the magnitude of init velocity.

then the new velocity just starts at that normalized vector * initial magnitude?

severe bay Jul 27, 2020, 7:13 AM

#

📎 unknown.png

#

0,5 is the rope position, -2, -1 is the player position

burnt imp Jul 27, 2020, 7:13 AM

#

ohhh

severe bay Jul 27, 2020, 7:13 AM

#

So you'll notice when I subtract their positions that way, the vector is the exact same as the rope

burnt imp Jul 27, 2020, 7:14 AM

#

thats genius

severe bay Jul 27, 2020, 7:14 AM

#

so you just check that, and if the distance of the vector is larger than the length of the rope, normalize it, multiply it by the ropes length, then move the player there

burnt imp Jul 27, 2020, 7:16 AM

#

thanks man, that makes sense. im sure ill run into a bunch of pitfalls but. great place to start

severe bay Jul 27, 2020, 7:17 AM

#

👍 You got it

undone lynx Jul 27, 2020, 2:36 PM

#

ahh so its like, keeping the player inside a unit circle between the grappled point

wooden bough Jul 27, 2020, 8:55 PM

#

hi, iam a beginner, i have created a easy 2d jump and run, but the physics are terrible and it hangs a lot

#

📎 Ohne_Titel.m4v

#

the code for the player is: https://hastebin.com/ulamazoguz.cpp

#

ever white thing has a 2d box collider

#

and the player has a 2d box collider too and a rigidbody 2d

#

can someone maybe help me? thx

little egret Jul 27, 2020, 9:10 PM

#

Anyone got a idea how to lift an object on a specific point (as example if i lift on the end of a bed, the start should stay on ground). i tried with different joints but had no luck. maybe the right name to search for is enough. Multiple Rigidbodys could be an idea but how should they be connected to each other?

graceful meadow Jul 27, 2020, 9:11 PM

#

@wooden bough please try this instead! sorry for the english https://hastebin.com/diqinowomu.cs

wooden bough Jul 27, 2020, 9:13 PM

#

thx @graceful meadow

#

i need some time to understand the code 🙂

graceful meadow Jul 27, 2020, 9:14 PM

#

let me know if you have questions, and trying it out will hopefully make it easier to understand!

stuck bay Jul 27, 2020, 9:54 PM

#

Do mesh colliders affect loading times - even if the collisions are very basic - and set to Convex?
I got a set of stairs and wondering if I should switch to box colliders

#

The stairs in question are maybe like 20-40 tris at best

#

When I set them to convex they turn into ramps lol

foggy rapids Jul 27, 2020, 9:55 PM

#

they wouldnt change load time, but they might slow down collision detection a bit if the mesh is poorly made

stuck bay Jul 27, 2020, 9:56 PM

#

got it. I'm developing a vrchat world and was told mesh colliders will slow down the time it takes to load into your world if you have a lot of them

foggy rapids Jul 27, 2020, 9:57 PM

#

Make a test to find out anyways 😄

#

the bigger/more complicated the mesh the more performance gain you can get from using a box collider

royal turret Jul 28, 2020, 11:53 PM

#

im having a problem with my 2D character

#

when i have an animation attached to my character, he just slowly goes down (i cant even control him), and he even goes through colliders

tranquil onyx Jul 29, 2020, 12:18 AM

#

Ok I'm trying to make a physics character controller for a VR game and stuck on something that should be very simple. I have a sphere collider on the headset, and I want to have a capsule collider that is always directly below the head (in-between the head and the ground) but I don't want this capsule collider to be affected by the rotation of the head. I tried jointing them together and locking rotation but that didn't work. Whenever the headset rotated the capsule collider stays directly under it. The only thing I can think of is to move the collider to a target position (under the headset) by adding forces or modifying the velocity, but then the head and capsule collider could get disconnected on certain collisions

#

any tips would be very helpful!

graceful meadow Jul 29, 2020, 12:23 AM

#

if nobody responds, there's #🥽┃virtual-reality

tranquil onyx Jul 29, 2020, 12:32 AM

#

thanks, I may post it there. It shouldn't matter that it's VR though, I just need a collider to stay under another collider without being affected by the rotation of the other, while still being "connected" together. Really though joints would solve my issues, maybe they can and I'm doing something wrong Im not sure

graceful meadow Jul 29, 2020, 12:34 AM

#

@tranquil onyx do you have your player set up like this?

📎 unknown.png

#

if you put the rigidbody on the player, then moving the player will move both the head and the body

#

and rotating the head won't change the position of the body

tranquil onyx Jul 29, 2020, 12:39 AM

#

ok I'm an idiot

#

tahnks

#

I knew it was something simple. I had the same hierarchy but had the movement code on the head still instead of the player

graceful meadow Jul 29, 2020, 12:40 AM

#

glad it worked!!

stuck bay Jul 29, 2020, 9:47 AM

#

how can i prevent this from happening? the player has a rigidbody, and it just gets stuck on the wall. i can't seem to figure out why this happens

📎 2020-07-29_05-46-00_Trim.mp4

#

@stuck bay Would it be because there's friction between the two when you push against it?

#

it happens when you're moving towards the wall

#

Yeah, that's what I'm thinking. Is the wall friction set to 0?

#

Nevermind, that might not be helpful

#

they aren't rigidbodies

#

Yeah

#

Hey guys, quick question - the character of my game keeps getting stuck on nothing and I'm unsure as to why. The player is just a square, and the ground is made of a tilemap + tilemap collider. Any suggestions?

📎 f1Ag41IfkS.gif

#

I've tried setting the player friction to 0

#

Yeah, nothing I'm doing's working

#

Sorry if this is super obvious by the way

#

Update 1 - Appears to get stuck inside the center of blocks, but still not sure why

#

*or how to fix it

willow vortex Jul 29, 2020, 10:48 AM

#

I can't tell from the video what part is the stuck part, is it supposed to slide on surfaces and not stop?

#

also, that WASD makes it seem like D is for down instead of right 😛

stuck bay Jul 29, 2020, 10:49 AM

#

@willow vortex yep my mistake there, and let me clarify-

#

I'm holding down the movement keys the whole time, but it randomly gets caught on nothing

willow vortex Jul 29, 2020, 10:50 AM

#

is that surface made of multiple boxes? if so, to narrow down the issue try a single sprite box thing and see if it has the same issues when you jump around in a similar way

stuck bay Jul 29, 2020, 10:51 AM

#

that'd make it simpler to fix, but nope sadly

the ground is made of a tilemap + tilemap collider

willow vortex Jul 29, 2020, 10:52 AM

#

I've never used those so I dunno what that means 😆 try it with a single surface regardless, it's for testing, not a fix

stuck bay Jul 29, 2020, 10:52 AM

#

It means that it's a single surface collider lol

#

Sure thing, one sec

willow vortex Jul 29, 2020, 10:56 AM

#

a simple box collider since that's pretty guaranteed to be smooth, tilemap collider sounds like it generates multiple shapes from the sprites it covers

#

or the issue is in the movement code where it stops reading your input for whatever reason until you press again? post that code too ¯_(ツ)_/¯

stuck bay Jul 29, 2020, 11:20 AM

#

@willow vortex

    void FixedUpdate() {
        rigidBody.velocity = new Vector2(moveInput * speed, rigidBody.velocity.y);
        moveInput = Input.GetAxisRaw("Horizontal");
    }

That's essentially my movement script

willow vortex Jul 29, 2020, 11:22 AM

#

whoa, the input lag on that 😆

#

Maybe doing moveInput += Input.GetAxisRaw("Horizontal"); in Update() and in FixedUpdate() you use it then set it to 0,0 afterwards

#

but that's unlikely to be the issue you're having

#

unless you're touching moveInput elsewhere

stuck bay Jul 29, 2020, 11:24 AM

#

I created a basic sprite with a box collider

#

and I haven't managed to encounter the issue anymore

willow vortex Jul 29, 2020, 11:24 AM

#

oof so it really is physics related then xD

stuck bay Jul 29, 2020, 11:24 AM

#

Damn

willow vortex Jul 29, 2020, 11:25 AM

#

you're in the right place, I'm out of ideas tho, as I said I've not used tilemaps so I'm not accustomed to their sneaky issues (which all things have tbh 😛 )

stuck bay Jul 29, 2020, 11:25 AM

#

Thank you for the help, though!

#

At least we narrowed down that it's a tilemap issue

graceful meadow Jul 29, 2020, 11:29 AM

#

just a hunch, but does it still get stuck if you add a composite collider to the tilemap?

#

if that still doesn't work then maybe try secretly giving the player a circle collider

stuck bay Jul 29, 2020, 11:30 AM

#

📎 unknown.png

#

I messed something up but I think it'll work

graceful meadow Jul 29, 2020, 11:30 AM

#

both would solve the issue if the edge of the- oop alrighty

stuck bay Jul 29, 2020, 11:32 AM

#

Okay sorry for interrupting you before but thank you so much for the help! I can't manually recreate the problem now, which I hope is a good sign

graceful meadow Jul 29, 2020, 11:32 AM

#

glad you got it working!!

stuck bay Jul 29, 2020, 12:46 PM

#

Hi! I found this article and got curious about what kind of integration the physics systems use https://gafferongames.com/post/integration_basics/

Gaffer On Games

Integration Basics | Gaffer On Games

Introduction Hi, I’m Glenn Fiedler and welcome to Game Physics.
If you have ever wondered how the physics simulation in a computer game works then this series of articles will explain it for you. I assume you are proficient with C++ and have a basic grasp of physics and mathem...

foggy rapids Jul 29, 2020, 3:21 PM

#

best answer i can find is semi-implicit euler

#

those are great articles btw keep reading!

unreal linden Jul 29, 2020, 4:52 PM

#

Is there a way I can automatically replace mesh colliders on multiple objects at once with a different one ?

#

Because I have a fractured mesh with 2 versions : a collider one and a visual one and I want to replace the colliders on the visual one with the ones of the collider version.

foggy rapids Jul 29, 2020, 4:56 PM

#

Set the mesh of the mesh collider to the collider version of the mesh

unreal linden Jul 29, 2020, 4:57 PM

#

yes... but I have about 200 objects

#

Manually doing it would take a long time

#

Since it is fractured

foggy rapids Jul 29, 2020, 4:57 PM

#

use a naming convention and write a script to do it

#

so that both versions have the same prefix or something

unreal linden Jul 29, 2020, 4:57 PM

#

I don't know how I would make such script, it isn't my field of expertise... I am a VFX artist

#

So how would I do it ?

uneven shore Jul 29, 2020, 6:10 PM

#

I have a character with movement where movement follows the floor direction (so moving is the same speed on horizontal and 40-degree slope floor).
I'm doing that by checking for floor below my character every physics-frame.
It works most of the times, but sometimes when my character goes from straight-floor to down-slope-floor, he keeps going and I'm missing the floor.
Any idea how to solve this?

#

A really bad illustration on what's going on.
Brown is floor
Blue is character
Red is what I want movement to be.
Green is what it actually is

📎 unknown.png

opaque siren Jul 29, 2020, 9:33 PM

#

https://gyazo.com/252d30fdb74731a158882571509bbe92

Gyazo

▶ Play video

#

how do I fix the player being able to hold A/D to cling to the side of a tile

uneven shore Jul 29, 2020, 9:36 PM

#

@opaque siren check the friction on the physics material. Setting the wall material to 0 should be enough

foggy rapids Jul 29, 2020, 9:37 PM

#

he probably needs that for the top of the tile

#

but he didnt give any details about his movement system

uneven shore Jul 29, 2020, 9:38 PM

#

@foggy rapids Not necessarily. I have my tiles set to 0 friction and my character is walking fine, and I'm using rigidbody.
But yeah, more info about his movement system will make it easier to help him

foggy rapids Jul 29, 2020, 9:38 PM

#

maybe wall grab is supposed to happen? if so the solution is really complex.
if you dont want any wallgrabbing at all dont let them steer while falling

opaque siren Jul 29, 2020, 9:43 PM

#

@uneven shore setting the friction to 0 doesn't fix it

uneven shore Jul 29, 2020, 9:44 PM

#

@opaque siren

but he didnt give any details about his movement system
do that 🙂

opaque siren Jul 29, 2020, 9:46 PM

#

okay so the player is moved by rigidbody.transform.Translate, the jumping is done by rigidbody.AddForce, and there is artificial momentum that is applied with rigidbody.transform.Translate

#

Let me see if the problem still happens when I remove momentum

#

Yeah it still happens even when I remove the momentum

#

Also all the Translating is done in FixedUpdate

foggy rapids Jul 29, 2020, 9:49 PM

#

are you supposed to be able to grab walls?

opaque siren Jul 29, 2020, 9:50 PM

#

no

foggy rapids Jul 29, 2020, 9:50 PM

#

find the code that's making him stick to the wall and stop it from running when he has downward velocity

#

@uneven shore do you have isGrounded code running? you could make use of that and, as the last job in the frame, set the Y coordinate to a fixed distance from the ground

uneven shore Jul 29, 2020, 9:52 PM

#

@foggy rapids wrong mention?

foggy rapids Jul 29, 2020, 9:52 PM

#

talking about your picture above

uneven shore Jul 29, 2020, 9:54 PM

#

oh. I'm already doing something like that. The problem seems to happen when the character moves too fast,
so that on frame X character is on the floor with normal (0, 1), while at frame X+1 the character is already in the air. I could set him to the ground, but it's still noticeable.

foggy rapids Jul 29, 2020, 9:54 PM

#

it's a tradeoff. Using physics gravity you'll get the green line, but simulating your own gravity you can get the red one but then you also have to apply gravity manually

uneven shore Jul 29, 2020, 9:55 PM

#

yeah doing my own gravity will probably fix that, i was hoping to avoid that though. Any other ideas?

foggy rapids Jul 29, 2020, 9:55 PM

#

the way i did it when i was trying to clone sonic was to treat each piece of ground like a rail and follow it at whatever velocity until you jump and detect the next "rail"

uneven shore Jul 29, 2020, 9:56 PM

#

Define "follow it" (the piece of rail)? how do you do it exactly?

foggy rapids Jul 29, 2020, 9:57 PM

#

calculate the distance to travel in the frame then move that distance along the path defined by the rail

uneven shore Jul 29, 2020, 9:57 PM

#

I thought about trying to predict the frame X+1, where character will be in the air due to high speed (can be done with ray tracing and velocity check).
But there's also the case where they may be holds, at which case you don't really want to follow the floor, so wasn't sure how to follow that idea.

foggy rapids Jul 29, 2020, 9:57 PM

#

i had found some spline making asset that helped

uneven shore Jul 29, 2020, 9:57 PM

#

mm I could create some "offline" (editor-code) spline data from the ground actually and use that yeah. I like that idea

opaque siren Jul 29, 2020, 9:58 PM

#

@foggy rapids for some reason the clinging only happens when it is a 1-high wall and the player is approaching from the right

📎 unknown.png

foggy rapids Jul 29, 2020, 9:59 PM

#

figure out the reason and the solution will probably be obvious

#

@uneven shore i like your idea of predicting though.
you could come up with a formula to determine how many frames to predict based on the current velocity
and employ your existing solution on all those frames

opaque siren Jul 29, 2020, 10:01 PM

#

Huh, it also doesnt happen with a regular boxcollider2D so I assume that means its something to do with it being a TilemapCollider2D

#

Okay I unchecked "Used by composite" which fixed it

uneven shore Jul 29, 2020, 10:02 PM

#

@foggy rapids There is no amount of frames; currently due to speed it happens in a single frame.

foggy rapids Jul 29, 2020, 10:02 PM

#

or generate sub-frames to do more fine grained ground checking

uneven shore Jul 29, 2020, 10:03 PM

#

@opaque siren the secret of unity colliders. gratz on finding the solution though 🙂

#

@foggy rapids Yeah played with it a bit before. I hate that.
Why do you like the prediction over the "rail" idea btw?

opaque siren Jul 29, 2020, 10:03 PM

#

@uneven shore well great... now I made a new bug. the same thing is happening now when its a multi-block high wall and you are approaching from the left

foggy rapids Jul 29, 2020, 10:04 PM

#

the rail idea is good but not very extensible, plus you'd have to draw splines all over

uneven shore Jul 29, 2020, 10:04 PM

#

@opaque siren just checked mine actually; what component did you check "Used by composite" on?

opaque siren Jul 29, 2020, 10:04 PM

#

Tilemap Collider 2D

uneven shore Jul 29, 2020, 10:05 PM

#

oh right I see it now; yeah mine's on too.

#

@foggy rapids Was thinking on making it mostly generated with editor code actually, with perhaps bit of manual editing (hopefully none)

#

Why not extensible?

#

@opaque siren I still think it's friction; I remember it happened to me when friction was on. Try to set the player friction to 0 as well?

foggy rapids Jul 29, 2020, 10:06 PM

#

then your whole game is pretty much locked to that movement style

uneven shore Jul 29, 2020, 10:06 PM

#

Also note you have multiple material properties: on the rigidbody and the colliders

#

@foggy rapids Only on the ground when player isn't jumping or something like that. That's pretty much the way ground movement works though.. What other cases are you thinking about?

foggy rapids Jul 29, 2020, 10:07 PM

#

@uneven shore you're using tiles?

opaque siren Jul 29, 2020, 10:07 PM

#

@uneven shore I just set every collider to a material with 0 friction and still nothing

uneven shore Jul 29, 2020, 10:07 PM

#

yup

#

@opaque siren do you also have a composite collider on your tilemap?

opaque siren Jul 29, 2020, 10:07 PM

#

yes

#

and I set that to 0 friction as well

uneven shore Jul 29, 2020, 10:08 PM

#

Geometry Type / Generation type values?

opaque siren Jul 29, 2020, 10:08 PM

#

Outlines / Synchronous

uneven shore Jul 29, 2020, 10:08 PM

#

try Polygons instead of outlines

#

I remember switching due to another bug actually (character falling through the floor), but still

opaque siren Jul 29, 2020, 10:09 PM

#

that fixed it

#

but now I need to make my grass tiles have perfectly square hitboxes since the player isn't able to jump up them while standing next to them

#

https://gyazo.com/a583c29ca348afc4fc8dacd41e703c2b

Gyazo

▶ Play video

uneven shore Jul 29, 2020, 10:10 PM

#

that fixed it
@opaque siren cool. cool cool cool.

#

The editor view of the collider at the last frame looks a bit weird actually. Not sure why it's like that though

#

But your tiles should probably be perfectly square hitboxes (they look like it anyway)

opaque siren Jul 29, 2020, 10:14 PM

#

📎 unknown.png

#

the end pieces' hitboxes were like that

#

so it caused the entire polygon to look different

foggy rapids Jul 29, 2020, 10:15 PM

#

@uneven shore Maybe instead of predicting you can refactor your movement to happen in fixed size steps (1, 1/2, 1/4, 1/8 tile size)
Then the faster you go the more steps you process in a frame.
that's more extensible than rails because you don't always have to follow a line

uneven shore Jul 29, 2020, 10:19 PM

#

I actually just refactored my code where in the old code I used sub-steps. I really hated it, feels a lot more error-prone.

#

And I'm not really sure what's wrong with following a line; my plan also isn't to follow the line like a rail, it's more like using the current rail exterior / normal data.

formal trail Jul 30, 2020, 1:26 PM

#

Is it better to do crouching by player down or by having 2 caps colliders and the upper one moves down?

willow vortex Jul 30, 2020, 1:41 PM

#

or resize the collider 😛

#

but be sure to check if it would hit anything if it expands or you'll get physics issues

#

you could also enable/disable the top collider too

#

but that won't work nicely if you expect the character to lift something up when they uncrouch

#

and probably neither does the resizing one, your moving of the top one would if you use rb.MovePosition

plucky plover Jul 30, 2020, 3:38 PM

#

Hey could anyone help me out?

I have a block placement method inside my 2D game. The issue is.... it places like 20 blocks inside one block because Im using update.

I tried using multiple 2D raycast methods to detect if there was already a block in the location... but nothing worked

#

currently... Im using this raycast:

#

    bool IsMouseOverBlock(Ray ray, RaycastHit2D hit) {
        bool returnBool = false;
        hit = Physics2D.Raycast(ray.origin, ray.direction, Mathf.Infinity);
        if(hit.collider.gameObject.tag == "Block") returnBool = true;
        return returnBool;
    }

#

Its giving me the error ```diff

NullReferenceException: Object reference not set to an instance of an object
PlayerCont.IsMouseOverBlock (UnityEngine.Ray ray, UnityEngine.RaycastHit2D hit) (at Assets/Scripts/Player/PlayerCont.cs:37)
PlayerCont.Update () (at Assets/Scripts/Player/PlayerCont.cs:45)

#

line 37 is cs if(hit.collider.gameObject.tag == "Block") returnBool = true;

#

could anyone help me out?

#

Oh yeah, this is whats inside my update()

#

        ray = Camera.main.ScreenPointToRay(Input.mousePosition);
        if (!EventSystem.current.IsPointerOverGameObject()) {
            if (Input.GetMouseButton(1)) {
                if (!IsMouseOverBlock(ray, hit)) {
                    Vector2 mousePos2D = Input.mousePosition;
                    float screenToCameraDistance = mainCamera.nearClipPlane;
                    Vector3 mousePosNearClipPlane = new Vector3(mousePos2D.x, mousePos2D.y - 102.4f, screenToCameraDistance);
                    Vector3 worldPointPos = mainCamera.ScreenToWorldPoint(mousePosNearClipPlane);
                    float delta = 102.4f;
                    if (worldPointPos.y <= 0) delta = 0;
                    GameObject currentBlock = ObjectPooler.Instance.SpawnFromPool("Block", new Vector3(worldPointPos.x - worldPointPos.x % 102.4f, worldPointPos.y - worldPointPos.y % 102.4f + delta, 1f));
                    SpriteMask spriteMask = currentBlock.GetComponent<SpriteMask>();
                    spriteMask.backSortingOrder = 0;
                }
            }
        }

foggy rapids Jul 30, 2020, 3:43 PM

#

if there's nothing there, hit will return null

#

also i think you have to let FixedUpdate run for rays to hit new objects

plucky plover Jul 30, 2020, 3:45 PM

#

@foggy rapids So should I put ray inside of FixedUpdate?

#

the variable

#

or the entire code

foggy rapids Jul 30, 2020, 3:46 PM

#

do raycasts in fixedupdate and dont let the user place more than 1 block per fixedupdate

plucky plover Jul 30, 2020, 3:48 PM

#

Thats what Im trying to figure out!

#

I need to allow drag placing.

#

but Im trying to use the raycast to limit it to only one block per "air"

foggy rapids Jul 30, 2020, 3:50 PM

#

I'd make a class who manages information about blocks.
instead of using raycasts just make this class the source of truth for where blocks are placed.
It could be as simple as a matrix of bools and when you place a block you tell it the x and y coordinate on the grid where you placed it.

plucky plover Jul 30, 2020, 3:52 PM

#

@foggy rapids here I tried what you mentioned earlier.
Would soemthing like this work?


    void FixedUpdate() {
        ray = Camera.main.ScreenPointToRay(Input.mousePosition);
        bool isMouseOverBlock = false;
        hit = Physics2D.Raycast(ray.origin, ray.direction, Mathf.Infinity);
        if(hit.collider.gameObject.tag == "Block") {
            isMouseOverBlock = true;
        }
    }

    void Update() {
        if (!EventSystem.current.IsPointerOverGameObject()) {
            if (Input.GetMouseButton(1)) {
                if (!isMouseOverBlock) {
                    Vector2 mousePos2D = Input.mousePosition;
                    float screenToCameraDistance = mainCamera.nearClipPlane;
                    Vector3 mousePosNearClipPlane = new Vector3(mousePos2D.x, mousePos2D.y - 102.4f, screenToCameraDistance);
                    Vector3 worldPointPos = mainCamera.ScreenToWorldPoint(mousePosNearClipPlane);
                    float delta = 102.4f;
                    if (worldPointPos.y <= 0) delta = 0;
                    GameObject currentBlock = ObjectPooler.Instance.SpawnFromPool("Block", new Vector3(worldPointPos.x - worldPointPos.x % 102.4f, worldPointPos.y - worldPointPos.y % 102.4f + delta, 1f));
                    SpriteMask spriteMask = currentBlock.GetComponent<SpriteMask>();
                    spriteMask.backSortingOrder = 0;
                }
            }
        }
    }

#

I already have a class that manages block info

#

Well

#

actually no thats for inventory

#

nvm

foggy rapids Jul 30, 2020, 3:53 PM

#

maybe, but your logic is backwards? you create a block if !isMouseOverBlock

plucky plover Jul 30, 2020, 3:53 PM

#

Sorry I edited it

#

I was returning in fixed update .-.

#

Im trying to be able to drag and place blocks

#

For quick building

#

but I only want one block to be placed per square

#

I kinda suck at C#... so I really dont know what to do here

willow vortex Jul 30, 2020, 3:57 PM

#

you're still not nullchecking hit.collider tho 😛

#

see example in https://docs.unity3d.com/ScriptReference/Physics2D.Raycast.html

marble sail Jul 30, 2020, 7:37 PM

#

do rigidbodies count as physics?

foggy rapids Jul 30, 2020, 7:58 PM

#

yes

marble sail Jul 30, 2020, 7:59 PM

#

then, i have this script ```csharp
using UnityEngine;

public class MovementScript : MonoBehaviour
{

public Rigidbody rb;
public float forwardForce = 2000f;
public float sidewaysForce = 500f;

void FixedUpdate()
{
    if (Input.GetKey("d"))
    {
        rb.AddForce(sidewaysForce * Time.deltaTime, 0, 0, ForceMode.VelocityChange);
    }
    if (Input.GetKey("a"))
    {
        rb.AddForce(-sidewaysForce * Time.deltaTime, 0, 0, ForceMode.VelocityChange);
    }
    if(Input.GetKey("w"))
    {
        rb.AddForce(0, 0, forwardForce * Time.deltaTime);
    }
    if (Input.GetKey("s"))
    {
        rb.AddForce(0, 0, -forwardForce * Time.deltaTime);
    }
}

}

foggy rapids Jul 30, 2020, 8:02 PM

#

huh?

marble sail Jul 30, 2020, 8:04 PM

#

when i say "w" for example and stop, the character moves like it's on ice

foggy rapids Jul 30, 2020, 8:06 PM

#

he probably is 😄

#

that behavior is determined by rigidbody properties and the physics material of both bodies

marble sail Jul 30, 2020, 8:07 PM

#

what settings would prevent that?

foggy rapids Jul 30, 2020, 8:08 PM

#

friction

#

mass

marble sail Jul 30, 2020, 8:08 PM

#

ok

#

i set the PhysicMaterial's frictions to 0 is that ok?

foggy rapids Jul 30, 2020, 8:10 PM

#

that will make it like ice. increase it until you get the movement you desire

marble sail Jul 30, 2020, 8:10 PM

#

ok

#

even with mass 9999999 it's still sliding

#

after setting physic materials to 9999999 i still was sliding why?

little egret Jul 30, 2020, 9:57 PM

#

ok anyone can explain this: i use the rb velocity to get the force of the impact, with discrete collision detection (which doesnt work well, because its very fast moving) i got in the first frame a velocity of 497, in the second frame 493 (as i expect, slowly decreasing), with continous or continous dynamic i got in the first frame 497, in the second something like 0.02 and at the moment of impact even 0,0,0. Why is that ? And how could i reliably measure the force of impact with ccd ?

#

trying a little slower the effect shows : is detecting the collision before it happens and "brakes" (in this case 2 frames before impact) , but how am i supposed to get the real velocity?

severe bay Jul 30, 2020, 10:40 PM

#

What are you trying to do?

#

I'm confused as to why you dont just use the velocity you have before hand

little egret Jul 30, 2020, 11:12 PM

#

i just want to have the velocity from the hit.rigidbody and it is zero when using continous collision detection, because it brakes before impact

#

i pause the game after every update and in the inspector i can see that the velocity on the rigidbody is close to zero 3 frames before impact

severe bay Jul 30, 2020, 11:53 PM

#

Not sure you can really do anything about that since it's the built in stuff

foggy rapids Jul 30, 2020, 11:54 PM

#

cache a few frames of velocity information -- problem solved

severe bay Jul 30, 2020, 11:54 PM

#

You could save the velocity and double check it until you actually receive the collision

#

beat me to it lol

little egret Jul 31, 2020, 12:12 AM

#

@foggy rapids thats what i do now, i cache 10 frames and delete the lowest 5, the 5 left i divide by 5

foggy rapids Jul 31, 2020, 12:14 AM

#

another useful tool for this kind of thing is circular buffer

little egret Jul 31, 2020, 12:15 AM

#

but i think i found out whats the problem if i detect the other way around (use oncollisionenter) i get the information, i just did it the wrong way i guess (that strange enough, works with discrete)

golden star Jul 31, 2020, 5:12 AM

#

If I check square distance between a projectile and my player on Update() instead of using a circle collider (assuming that adding a collider for the purpose I want requires significant work), will that be much less efficient or is the difference negligible

#

(In 2D space)

loud moon Jul 31, 2020, 5:27 AM

#

What's the point of Target Velocity for Configurable Joint. I thought it was to determine how fast the anchor should move towards connected anchor, but it seems to move at any speed regardless. Based on the Spring

undone lynx Jul 31, 2020, 7:48 AM

#

@golden star shouldnt even be a blip on the radar yet

little egret Jul 31, 2020, 10:53 AM

#

hello, i really have a hard time to understand how to use unity physics on an non physics character.
i made a lot of tests now, and can't find an solution.
In OnCollisionEnter:
i could use the direction from rb.transform to the object i hit to add a force in that direction.
i could also use the reversed collision.impulse to move it in that direction.

both ignore the angularvelocity, i guess there is no easy way to do that, if there is any.
there is still no impulse for contact points in the Collision object, even though it's exposed in physx, but not in unity.
it is impossible to add the right torque to an object without that.

so i decided it must be enough to fake it without torque, just adding an force in the direction between the two transforms.
BUT ... i need to know how much force in this direction.
i directly output collision.impulse in OncollisionEnter and a frontal hit results in a impulse.magnitude of 29, a hit on the left side of the character gives me an impulse of 69 ?
what do i missunderstand ? how am i supposed to get a indicator that show me how hard the object is hit ?
The relativeVelocity is useless because it ignores where the impact was, so a frontal hit would be the same than a litte hit on the bounds of the character and i see no other usefull information.

#

im thinking about using the yaxis difference between the velocity direction and the impulse direction, the smaller it is, the harder the hit but can i really not get that information from an Collision object?

stuck bay Jul 31, 2020, 12:31 PM

#

Why doesnt this show anything in console:

            print("New zone");
        }```

graceful meadow Jul 31, 2020, 12:32 PM

#

are you using 2d? because OnTriggerEnter2D exists

stuck bay Jul 31, 2020, 12:33 PM

#

im in 3d

graceful meadow Jul 31, 2020, 12:33 PM

#

i'd check the collision matrix, contact pairs and make sure both objects have rigidbodies

stuck bay Jul 31, 2020, 12:34 PM

#

rigidbody is needed for an is trigger?

graceful meadow Jul 31, 2020, 12:34 PM

#

depends on your contact pairs

#

you can find them under project settings -> physics!

stuck bay Jul 31, 2020, 12:35 PM

#

ok ill check it

graceful meadow Jul 31, 2020, 12:36 PM

#

if none of that works, keep me updated because ive found collision questions are the hardest to answer 😩

stuck bay Jul 31, 2020, 12:38 PM

#

it is in default

graceful meadow Jul 31, 2020, 12:39 PM

#

try changing it to enable all contact pairs?

#

and for the object without a trigger and the one with a trigger, what rigidbodies do they have?

stuck bay Jul 31, 2020, 12:41 PM

#

the without a trigger has a default rigidbody and the trigger had no rigidbody i added a default rigidbody but it seems to not affect

#

the all contact pairs doesnt work

#

in the code warnings it says that the OnTriggerEnter is callaed but never used that could be the problem?

graceful meadow Jul 31, 2020, 12:48 PM

#

oh wait that's,,

#

hang on can you hastebin your entire code?

#

it might just be a misplaced bracket https://answers.unity.com/questions/1572481/ontriggerenter2d-declare-but-never-used-how-do-i-f.html

stuck bay Jul 31, 2020, 1:20 PM

#

thx it was just a misswritten bracket XD

#

I was putting it in a void i had before it

ruby prawn Jul 31, 2020, 2:58 PM

#

Hello how can I recreate the rb.AddForce function?, The goal is to understand how the force acts

#

i did something like this for gravity: https://codeshare.io/5wgge9
is the good practice ?, should I cancel the force once the object hits the ground?

willow vortex Jul 31, 2020, 3:13 PM

#

rb.velocity += impulseVector * Time.deltaTime; is similar to AddForce() with impulse type, you'll need to divide vector by mass to get it similar to normal force I guess 🤔

#

the way your code is set up is going to simulate velocity on its own and ignore any other velocities that might come from bumps or whatever... is that intended?

#

and your Fgravity is too high, you don't need to multiply by mass since it's not a force, it's a velocity addition (acceleration) 😛

ruby prawn Jul 31, 2020, 3:51 PM

#

so i should already moved the code into the update function? at first if I want to manage the physics dt?

#

the goal is to experiment a little physics, with the 3 law of netwon and the principle of Galilée

#

the example in the script I only want to apply the force of gravity that allows you to stay on the ground.
and so I did not apply any outside force, like the winds ect

ruby prawn Jul 31, 2020, 4:09 PM

#

Vector3 Fgravity = Vector3.down * 9.81f;

velocity = velocity + Fgravity * dt;
position = position + velocity * dt;

rb.velocity = velocity;
rb.position = position;

#

is that correct?

willow vortex Jul 31, 2020, 4:12 PM

#

why are you setting position too, that defeats the purpose of velocity xD

#

and I said nothing about moving to Update() 😛 I'm talking about the math and the logic

#

if you want to move something physically so it does collisions properly, rb.MovePosition instead

#

otherwise stick with rb.velocity only, and read it too if you want other things to be able to add to it, like in my first snippet above

torpid rivet Jul 31, 2020, 4:14 PM

#

how do you make a first person game

willow vortex Jul 31, 2020, 4:15 PM

#

unitylearn has a FPS template

torpid rivet Jul 31, 2020, 4:15 PM

#

thx

ruby prawn Jul 31, 2020, 4:16 PM

#

Okay so the position will serve me just to determine this trajectory? so for him given a speed I don't need it

#

with velocity it's up to me to manage the third laws of netwon? (action reaction)

leaden token Jul 31, 2020, 4:16 PM

#

hey im super new to unity and idk anything about C# or anything like that and Ive been trying to get an active ragdoll working for the past like 2 weeks. Does anyone want to join a call and help me out a bit?

torpid rivet Jul 31, 2020, 4:17 PM

#

me too

leaden token Jul 31, 2020, 4:17 PM

#

hash u can just use google

#

it wont take u long at all

torpid rivet Jul 31, 2020, 4:18 PM

#

here

#

https://learn.unity.com/course/create-with-code-live-summer-2020?start=true

Unity Learn

Create with Code Live - Summer 2020 - Unity Learn

Join us for Create with Code Live, a free, four-week course that’ll teach you foundational skills in Unity, C# programming, and game design through a mix of self-paced learning and live instruction. Gain the skills to get Unity Certified. Register now (register one time to be ...

leaden token Jul 31, 2020, 4:22 PM

#

this isnt really what i need but cool

undone lynx Jul 31, 2020, 8:59 PM

#

@little egret i dont remember any details yet

#

but there were some forums of assets i skimmed a little

#

kinematich character controller or smth

#

and they use a physics query to compute depenetration

#

https://docs.unity3d.com/ScriptReference/Physics.ComputePenetration.html

#

and i think u can get all the contacts in a collision too? u might be able to get away with using the total collision.impulse as an average

#

and spread it across all contact points

modern iris Jul 31, 2020, 9:01 PM

#

How to fix high speed collision detection?

📎 video0.mp4

undone lynx Jul 31, 2020, 9:01 PM

#

changing the rigidbody collision detection to Continuous helps

graceful meadow Jul 31, 2020, 9:02 PM

#

lowering Time.fixedDeltaTime helps too

undone lynx Jul 31, 2020, 9:02 PM

#

one thing to note is

#

if its one sphere then i think itll be fine

#

but physics is hard to predict, u might want to cap the movement speed unless its absolutely necessary for ur game

#

try changing the collision detection mode to continuous on ur sphere and try tho

modern iris Jul 31, 2020, 9:10 PM

#

okay thanks

little egret Jul 31, 2020, 9:24 PM

#

@undone lynx i use this already for the character controller, i don't even care about the torque anymore, but i need information from an rigidbody collision that tells me if it is a full hit or just a grazed. And i can't see how i could get this from a Collision Object, which is very disappointing. I use the angle change of the velocity direction now, it works but it is not what i was going for.

undone lynx Jul 31, 2020, 9:25 PM

#

u can compute the penetration no. and know if an object is "inside"

little egret Jul 31, 2020, 9:30 PM

#

@modern iris 2 important things i learned last days, if it's really high speed: continous or continous dynamic / if it's still not good enough, raycast in transform.forward in the length of the next velocity to see if there is a collision next frame and if that is still not enough sweeptests. Also important: move rigidbodys ONLY by Force if you move by translate or set the transform you want have fun with rigidbodys. And if you do that all, it still sucks sometimes 😄

#

@undone lynx i can't see what the penetration test should help for this case, i just need info about the angle of the collision. i don't wanna solve collisions by myself. this works very good already with the character controller.

modern iris Jul 31, 2020, 9:32 PM

#

thanks! well, im not making THAT fast game, i just set very high speed for testing and saw that my object is getting through collision so i thought better if i fix that even if player can't be that fast, and setting to Continuous helped

undone lynx Jul 31, 2020, 9:32 PM

#

hmm isnt the angle of collision the normal?

#

or cant u get it using the normal

little egret Jul 31, 2020, 9:32 PM

#

thats what im doing also dawiss, i use at least double the speed the player could go to make sure it works in all cases

#

you can

#

you can have the normals of any contact

undone lynx Jul 31, 2020, 9:35 PM

#

hmm good luck tho

#

i dont think i fully understand yet

#

what u want to know is how "hard" the player was hit

#

right?

little egret Jul 31, 2020, 9:36 PM

#

but that doesn't help with torque, because u have just the overall impulse. but again, that's not the problem anymore. i need to know how "hard" the hit is. And i can't see how with the given information. the impulse is shorter on a direct hit than on a angled hit. i test again later, maybe i can use that somehow.

undone lynx Jul 31, 2020, 9:36 PM

#

but the data provided by the collision is not enough for u

little egret Jul 31, 2020, 9:36 PM

#

right

undone lynx Jul 31, 2020, 9:37 PM

#

The total impulse is obtained by summing up impulses applied at all contact points in this collision pair. To work out the total force applied you can divide the total impulse by the last frame's fixedDeltaTime.

#

can u try this value?

#

var force = collision.impulse / Time.fixedDeltaTime;

#

see if this is workable

little egret Jul 31, 2020, 9:39 PM

#

tryed already

undone lynx Jul 31, 2020, 9:39 PM

#

how does relativevelocity pan out for u>

little egret Jul 31, 2020, 9:39 PM

#

its the same then impulse, just a higher number because you divide by 0.02

#

completly useless because the other object is not an physics object, but even when it is, it doesnt tell me anything about the angle or the quality of the hit

#

i dont even know hot to explain it 😄

undone lynx Jul 31, 2020, 9:40 PM

#

perhaps u can try smth

#

heres a layman idea from me

#

u want the "hit" to be more impactful

#

if it is closer to center of mass

#

right?

#

upon a collision, u can perhaps scale the relativevelocity

#

if the relative velocity is similar in direction towards the center of mass

#

it will have more impact

#

u can try using the dot product of"relativeVelocity" and "contactPoint -> playerCenterOfMass"

#

get it?

#

would this work nicer

little egret Jul 31, 2020, 9:43 PM

#

thats a good idea

undone lynx Jul 31, 2020, 9:43 PM

#

and u can use a custom cutoff

little egret Jul 31, 2020, 9:43 PM

#

basically what i do now , just with dot product

undone lynx Jul 31, 2020, 9:43 PM

#

if the similarity is greater than, say, 0.5, consider it a hit

#

otherwise ignore

little egret Jul 31, 2020, 9:43 PM

#

i scale the force i give to the kinematic character by that

#

so if its a direct hit it will be pushed far away

#

if its just a grazed hit i push him in the normal direction with a lower value

undone lynx Jul 31, 2020, 9:45 PM

#

so can u try explain to me the situation

#

in which u want to have more info

#

i am curious, i would like to understand the issue

#

in which u want to have more info
as in the situation where the physics api falls flat

little egret Jul 31, 2020, 9:46 PM

#

i try to make a video of the situation and show you then what i do. maybe i miss something important. it works btw now, but i don't like the way. i think there must be an easier way.

undone lynx Jul 31, 2020, 9:46 PM

#

ye im interested in the solution

#

it is a kinematic rigidbody right?

little egret Jul 31, 2020, 9:47 PM

#

no

undone lynx Jul 31, 2020, 9:47 PM

#

and u are trying to solve the physics where other object hits player

little egret Jul 31, 2020, 9:47 PM

#

yes thats what i try

#

but the character has no rigidbody

undone lynx Jul 31, 2020, 9:47 PM

#

ahh

little egret Jul 31, 2020, 9:47 PM

#

just a capsule collider that solves the collisions

#

BUT

#

i have an kinematic rigidbody in it

#

because of the problem

undone lynx Jul 31, 2020, 9:48 PM

#

i see

#

so u would like to get rid of the rigidbody

#

and use ur own routines

little egret Jul 31, 2020, 9:48 PM

#

if possible yes

undone lynx Jul 31, 2020, 9:49 PM

#

when u have a moment, let me know here about the situation

little egret Jul 31, 2020, 9:49 PM

#

they work very good for solving collisions, pushing rigidbodys and so on

#

never thought the physics engine will make problems now, colliding with it

#

yeah i finish something real quick, then i try to showcase it better

#

my test class: https://hatebin.com/hkzrpfkzjk

#

basically in the scene are just 2 cubes with rigidbodys, both without gravity, one is kinematic one is collision detection continous / continous dynamic , the one that is not kinematic has this script on it

#

if you push H it will shoot and the rays will show all kind of info and some more info in the console

#

what i want is just tell: how "hard" was the hit (direct hit / grazed hit) and whats the impact force (to move the kinematic in the right direction with the right force)

#

you should maybe comment out: collision.gameObject.GetComponent<Rigidbody>().isKinematic = false; that was just another test, that doesn't help, basically i don't even want the kinemtic rigidbody, but without i couldn't get it work at all

#

also: if i use the first hit as a direction it sucks because i have to take the direction to the transform and that (if you rotate the cube you hit) give you complete false information

#

this is btw what im doing now: https://hatebin.com/lhprltsmtf

undone lynx Jul 31, 2020, 10:34 PM

#

btw theres nothing wrong with using a kinematic rigidbody

#

thats what links u to the physics api

#

kinematic rb is as much as u can get to a physics connected object without actually being influenced by the physics

#

ill take a look at that later

little egret Jul 31, 2020, 10:39 PM

#

ok i also see no downsides so far by using it.

formal trail Jul 31, 2020, 11:24 PM

#

Can someone explain whats the difference between ForceMode.Acceleration and ForceMode.VelocityChange? Both are changing velocity over time wighout taking mass into account altho VelChange seems to be much more aggresive and I dont know why.

#

VelocityChange is basically Impulse but without mass?

#

thats what im understanding from the docs but im not sure its correct understanding

graceful meadow Jul 31, 2020, 11:31 PM

#

velocity change sets velocity directly, not taking anything else into account afaik

#

acceleration probably does the same but for itself

little egret Jul 31, 2020, 11:31 PM

#

Force Add a continuous force to the rigidbody, using its mass. Acceleration Add a continuous acceleration to the rigidbody, ignoring its mass. Impulse Add an instant force impulse to the rigidbody, using its mass. VelocityChange Add an instant velocity change to the rigidbody, ignoring its mass.

formal trail Jul 31, 2020, 11:32 PM

#

yeah i know it says that

#

but i wasnt sure exactly what that means @little egret

little egret Jul 31, 2020, 11:33 PM

#

oh sry, most people don't scroll down enough

formal trail Jul 31, 2020, 11:34 PM

#

like for example how fast does it change speed

#

its per second?

#

lets say i do rb.AddForce(Vector3.forward * 10f, ForceMode.Acceleration) does that mean that after 1 second my rb will have forward speed of 10f?

#

also does it try to "force" the change?

little egret Jul 31, 2020, 11:38 PM

#

velocitychange changes to the new velocity, acceleration should give in that case 10f / sec to the velocity

#

but im not sure, should be easy to try it

formal trail Jul 31, 2020, 11:38 PM

#

lets say that I would need an equal force of 10f when using ForceMode.Force, but there is another force on the body in the opposite direction of magnitude 10f, will ForceMode.Acceleration increase the effective force to 20f to counteract this another force?

little egret Jul 31, 2020, 11:38 PM

#

just do it, and log the velocity in a list with time.deltatime or / time

formal trail Jul 31, 2020, 11:50 PM

#

@little egret checked it and Acceleration works by applying force that would have resulted in wished velocity change provided no other forces act on the body

#

so if you place an 1f heavy cube in front of another 1f heavy cube that is being accelerated at 1f ForceMode.Acceleration the resulting acceleration will be 0.5f, the same as if you did 1f ForceMode.Force

little egret Jul 31, 2020, 11:54 PM

#

ok , i think i never used it. But good to know, the documentation is sometimes not really helpfull

copper zephyr Aug 1, 2020, 12:47 AM

#

im using this code to change the scene, when i collide with a object the scenes change, but when i collide with the object the scenes dont change what is wrong?

📎 unknown.png

little egret Aug 1, 2020, 1:31 AM

#

ok need bed

willow vortex Aug 1, 2020, 10:24 AM

#

@copper zephyr

when i collide with a object the scenes change
when i collide with the object the scenes dont change
you should clarify the above, if you still need help 😛

#

also use .CompareTag() instead, faster and will throw errors if you type an inexistent tag

graceful meadow Aug 1, 2020, 1:23 PM

#

collisions are the abs worst to debug, but check your contact pairs, rigidbodies and collision matrix too

shrewd peak Aug 1, 2020, 2:28 PM

#

Hey is it possible to do IK with physics

#

I want to do a VR hand and think it would be easier to set the position of each end of the finger and IK does the rest of the finger and makes sure the parts of the finger don’t intersect geometry?

#

Is that possible

ruby prawn Aug 1, 2020, 3:20 PM

#

Hello how to apply the force of gravity in unity? with useGravity disabled is without AddForce?

#

acceleration = Vector3.down * 9.81f;
velocity = velocity + acceleration * dt;

#

I did something like this, or once hit the ground I cancel the force

#

It's OK May, the OnCollisionEnter takes any collision, the thing is a car for example must be able to have the 4 wheels on the ground

bitter schooner Aug 1, 2020, 5:44 PM

#

For programming a grappling hook, I was thinking of pretty much using spring physics. Does that generally work out well?

#

Or would it be better to check the distance between the player and the length of the rope and just move the player back if they exceed that distance?

stuck bay Aug 1, 2020, 6:00 PM

#

Hello everyone I tried to make this readable

#

📎 unknown.png

#

is there any reason it shouldnt be working? I just doesnt move at all

ruby prawn Aug 1, 2020, 6:01 PM

#

rb.AddForce(Vector3.down * (9.81f * Mass), ForceMode.Force);
shouldn't this define 9.81 m/s² ?

twin wedge Aug 1, 2020, 6:09 PM

#

hi all, I'm looking to spawn an images in a random (x,y) position in front of a canvas in camera space. can someone point me in the right direction? I want to make them fly in 3d space, or look like it.

dusky stone Aug 1, 2020, 8:01 PM

#

Can I get some help?

#

I've just modelled a table in blender and imported it into unity

#

I can't get the collisions and rigidbody physics to work though

#

and if I mark it convex it treats the entire area of the table as a cube

#

ignoring the space that is supposed to be air

little egret Aug 1, 2020, 10:09 PM

#

just create 5 box colliders, and place them on the table and on the 4 table legs ?

#

@dusky stone

dusky stone Aug 1, 2020, 10:10 PM

#

yo i got it

#

i seperate the meshes into seperate convex pieces in blender

#

so that they each have their own mesh in unity

#

then i can add a mesh collider

#

😃

little egret Aug 1, 2020, 10:12 PM

#

for a table its much easier to add 4 box colliders, if you don't care about performance and don't need a lot of them mesh colliders should do it also 😄

dusky stone Aug 1, 2020, 10:16 PM

#

ahhh okay

#

i just wanted to test that way since it is supposed to be much more performant in the long run

late kettle Aug 1, 2020, 10:21 PM

#

I think I've miscalculated some physics stuff

#

Basically, I'm making a Flappy Bird-style game.

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With every obstacle passed, the gameplay speed will increase.

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I've done this by having a gameSpeed variable that increases with each obstacle

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The player's forward speed, gravity force and jumping force are multiplied by gameSpeed

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In theory, this shouldn't change the trajectory of the player's jumps, just make them faster

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But in practice, the player ends up jumping higher and higher

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Anyone know how to calculate it right?

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GameManager.Instance.SpeedUp();
                    rb.AddForce(0, 0, startSpeed * GameManager.Instance.speedIncrement); //this is the forward speed
                    constantForce.force = new Vector3(0, startGravity * GameManager.Instance.gameSpeed, 0);
                    flapForce = startFlapForce * GameManager.Instance.gameSpeed;

little egret Aug 1, 2020, 10:44 PM

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this part shouldn't be the problem , maybe it's the way you add the force? you can debug.log every force with vector3.ToString("F4") , should help you fast to find the problem, if the startFlapforce and startgravity are the same the problem should be anywhere else

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also, i don't know if its what you want, you use 2 different variables that we can't see, speedIncrement and gameSpeed

late kettle Aug 1, 2020, 10:50 PM

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startFlapForce is 6.5, startGravity is -20

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gameSpeed starts out as 1, speedIncrement is 0.05 and SpeedUp() adds speedIncrement to gameSpeed

little egret Aug 1, 2020, 11:00 PM

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you could debug.break() on Time.Framecount 20 as example, check the 3 vectors if the numbers are ok, if yes , search whereever you add the forces and check if you apply the same forces, try to disable everything that could influence it, like rigidbody.drag or whatever could, depends on your case

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@undone lynx i'm still interested if you can figure out a better way for the problem with the rigidbody / kinematic rigidbody collision, whenever you have time

late kettle Aug 1, 2020, 11:06 PM

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@little egret My rigidbody has no drag, otherwise I don't know what these mean UnityChanSorry

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This part is what sets the momentum when flapping

void Jump(int xDirection)
    {
        rb.velocity = new Vector3(flapForce * xDirection, flapForce, rb.velocity.z);
    }

little egret Aug 1, 2020, 11:17 PM

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why is direction an int? you multiply the flapforce there again on the xaxis to make it faster ? but modifying the velocity directly is not a good idea, maybe try addforce with forcemode velocitychange, also im pretty sure this is a lot easier for you without physics engine

late kettle Aug 1, 2020, 11:20 PM

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why is direction an int?
Because there's only three directions to jump: up, up-left and up-right

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I can change it to addforce to see if it helps

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How would this work without a physics engine?

little egret Aug 1, 2020, 11:27 PM

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you could use triggers for colliders and move by translate or setting positions, the physics will make a lot things easier, but also a lot harder, especially when you want to do something that doesn't really care about physics like the movement of a flappy bird like object, but that's just an personal opinion, i don't know whats your goal if you wanna experiment with the physics engine and learn from it, it's also ok to try it like you do

late kettle Aug 1, 2020, 11:29 PM

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Yeah, I think I'll stick to the physics

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But thanks for the help

bitter schooner Aug 2, 2020, 3:17 AM

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Hey, I'm repeating a question. If that's not allowed, just let me know.

Or would it be better to check the distance between the player and the length of the rope and just move the player back if they exceed that distance?```

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I'm currently thinking that programming it like a spring will have benefits when I want to program the "draw player towards grapple point" functionality, because all I'll need to do is adjust a number when the player presses a button and the spring will pull them stronger as if the spring was more taut then it actually is.

undone lynx Aug 2, 2020, 3:21 AM

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@bitter schooner a spring sounds cool for that

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https://www.reddit.com/r/Unity3D/comments/38kqo0/text_tutorial_3d_variablelength_rope_grappling/

r/Unity3D - [Text Tutorial] 3d variable-length rope grappling hook!

27 votes and 6 comments so far on Reddit

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heres some info on setting up a configurablejoint for it

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theres a couple tutorials online, most of them have own way of things

bitter schooner Aug 2, 2020, 3:25 AM

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I want the physics to kinda behave like this, so I think a spring works.
https://gfycat.com/thunderousunconscioushorseshoebat

Gfycat

2020-08-01 22-53-48

▶ Play video

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I'll look online and see what I can find. I was just curious if anyone here had experience with making their own grappling hooks.

abstract aurora Aug 2, 2020, 11:33 AM

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does anyone know if there is a way to prevent joints from going beyond their limits ?

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like for example if a kinematic object is pushing them, to have them i guess function as a straight up solid object when they are at their limit.

marble blade Aug 2, 2020, 12:01 PM

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yep

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@abstract aurora just leave the spring strength to zero for an infinite resistance

graceful meadow Aug 2, 2020, 12:12 PM

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@abstract aurora if you want joints to be more aggressive about holding distances, increase this

📎 unknown.png

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under project settings -> physics

abstract aurora Aug 2, 2020, 12:15 PM

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so what will happen if a kinematic object tries to push a hinge out of place, will it just clip through or something ?

graceful meadow Aug 2, 2020, 12:16 PM

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ive got no clue but m pretty curious to find out

abstract aurora Aug 2, 2020, 12:16 PM

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i dont know about the linear correction thing but i dont think benoits suggestion fixes anything, kinematic objects can still push joints out of place

graceful meadow Aug 2, 2020, 12:16 PM

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i think both would get pushed back a little as the hinge gets slightly displaced

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alrighty

abstract aurora Aug 2, 2020, 12:17 PM

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well one is kinematic so it cant be pushed back

graceful meadow Aug 2, 2020, 12:18 PM

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distance joints are probably more performant than spring joints with zero strength too but mayb im missing smth

abstract aurora Aug 2, 2020, 12:19 PM

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i dont know what that is. i just checked it seems there is only a 2d distance joint

graceful meadow Aug 2, 2020, 12:19 PM

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oop that makes sense

abstract aurora Aug 2, 2020, 12:29 PM

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i dont think its so much as like an error or overshooting i think the joints are just designed to be able to be pushed out of place

marble blade Aug 2, 2020, 12:30 PM

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the collision has the priority on the joint, so if you push a kinematic rigidbody too hard, the joint will brake of course. This is only trying to resolve a non-physic simulation realisticaly

abstract aurora Aug 2, 2020, 12:30 PM

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if you have a hinge joint and like a door on it, and then a wall blocking the door, when you push the door into the wall it starts spazzing out and eventually some clipping will happen

marble blade Aug 2, 2020, 12:30 PM

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My advice works on a situation were bodies are not kinematic

abstract aurora Aug 2, 2020, 12:30 PM

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ok sure but is there some kind of standard solution people have figured out to avoid the joint breaking

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like scripting logic

marble blade Aug 2, 2020, 12:31 PM

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this is all up to what you are trying to achieve

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it is completly possible to have a script thath will replace your joint in it's limit, but it will be at a cost or another

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if you force physics like this, the next frame will correct the situation back and you will have jitter

abstract aurora Aug 2, 2020, 12:32 PM

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is there a way to tell if the joint is "out of place" ?

marble blade Aug 2, 2020, 12:32 PM

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what kind of joint?

abstract aurora Aug 2, 2020, 12:33 PM

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well ive seen both fixed and hinge joints get out of place

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like for example can i detect when it starts getting out of place and just set it to kinematic

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and then i guess at some point try to figure out when to set it back to non-kinematic ?

marble blade Aug 2, 2020, 12:35 PM

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can't you solve the problem at its root, trying to find a solution where your kinematic body never push the joint unrealistically?

abstract aurora Aug 2, 2020, 12:35 PM

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probably just have to stop using joints tbh, its for vr

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so the users head is kinematic

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probably would be too motion sick to have the head follow unity physics

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i guess i can just disable collisions with the head

marble blade Aug 2, 2020, 12:36 PM

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of course, but you can attach a physic head to the vr head

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with a fixed joint for example

abstract aurora Aug 2, 2020, 12:37 PM

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ah i see and have the real head not do any collisions

marble blade Aug 2, 2020, 12:37 PM

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that will allow, for example, a physic hand no going into a wall, while the VR hand can go.

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the physic hand could be teleported back to the VR hand when the VR hand does not collide anything anymore

abstract aurora Aug 2, 2020, 12:39 PM

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yea i understand i think that could work fine

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although im just trying some stuff now (outside of vr) and i can still get joints to move out of place even with 2 non-kinematic bodies

marble blade Aug 2, 2020, 12:39 PM

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well this is a vast subject I'm afraid, with a lot of strange cases

abstract aurora Aug 2, 2020, 12:39 PM

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actually i guess its ok it depends on the mass

marble blade Aug 2, 2020, 12:39 PM

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About the joint, imagine a door, if you don't set any connected body, it will be connected to the world and won't be able to move

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the limit, though, will be able to brake if you push it with a kinematic body, but you can avoid that in a script. If the limit is passed, just rotate back to the limit each turn

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it may become more complicated for more complex joints, though

abstract aurora Aug 2, 2020, 12:41 PM

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ok thanks anyway i think your suggestion to attach stuff to the vr head and body will work

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i was just testing stuff in the editor and it seems joints can still be pushed out of place if one of the masses is much larger than the other, but as long as that is not the case it seems to work pretty well

marble blade Aug 2, 2020, 12:42 PM

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have fun with joints, if you can !

abstract aurora Aug 2, 2020, 12:44 PM

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cool thanks

late kettle Aug 2, 2020, 3:38 PM

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@little egret I tried addforce with forcemode velocitychange, the problem now is just that it adds to the Y-axis speed instead of setting it

rich turtle Aug 2, 2020, 4:45 PM

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Would anyone be able to lend some assistance with one side of, I'm guessing Physics that has broken when upgrading from Unity 4 to 5? Haven't used Unity in a few years

ruby prawn Aug 2, 2020, 6:32 PM

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what is the difference between velocity and AddForce?

foggy rapids Aug 2, 2020, 6:39 PM

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velocity is what the physics engine uses in it's integration.
AddForce modifies velocity.

ruby prawn Aug 2, 2020, 6:44 PM

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ok so if i want a constant speed of 1 m/s i should not be using AddForce? may rather velocity

foggy rapids Aug 2, 2020, 6:46 PM

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depends on the forcemode

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check the documentation on those

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nothing is wrong with setting velocity directly

ruby prawn Aug 2, 2020, 6:47 PM

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I just looked I ask because I did not understand very well

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I want a constant velocity of 1 m/s so with velocity I do velocity = new Vector (0, 0, 1) = 1 m/s
so this cannot be reproduced with the AddForce function?

ruby prawn Aug 2, 2020, 7:13 PM

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ok so for gravity i did that

rb.AddForce(Vector3.down * 9.81f * Mass);

it's ok, but how do I go about canceling the force in contact with the ground? OnCollitionEnter detects any collision so if the object is a cube it will not be properly grounded

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how does unity work with gravity on?

foggy rapids Aug 2, 2020, 7:49 PM

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with gravity on, objects accelerate Vector3.down at whatever rate you specified in physics settings

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most people use the collision detection or raycasting to figure out if the object is on the ground and set a flag on the object for it. Then use that to know when to use the appropriate behavior

ruby prawn Aug 2, 2020, 7:59 PM

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okay is the force of gravity for a car for example on the ground it is 0? or it must be applied of 9.81N in constant?
is this force to be divided by the number of grounded wheels?

foggy rapids Aug 2, 2020, 8:03 PM

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that depends how you build the car

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gravity wont make something fall through something it collides with

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i dont recommend getting into vehicle physics though it's too complicated

ruby prawn Aug 2, 2020, 8:14 PM

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I don't recommend going into vehicle physics even though it's too complicated ? I didn't understand that sorry

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i did something like that

int n = 4;

Vector3 force = (Vector3.down * 9.81f) / 4;

for (int i = 0; i < n; i++)
{
    Wheel wheel = m_Wheels[i];

    if (wheel.IsGrounded) n--;
}

acceleration = n * force;

foggy rapids Aug 2, 2020, 8:30 PM

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i never said even

shrewd peak Aug 2, 2020, 8:43 PM

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so i need some help

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📎 unknown.png

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i have 3 objects

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right hand physics

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left hand physics

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and head physics

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i want to "link" them

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so if the left hand physics obj pushes down the head and right hand go up

twilit idol Aug 2, 2020, 9:46 PM

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📎 Halp.mp4

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Added interpolation onto my game's rigidbodies and now the moving platforms have this "sticky" effect that slows the players move speed down. Anyway to fix this?

graceful meadow Aug 2, 2020, 11:04 PM

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i've never worked with interpolation before, but only the player has it turned on, right?

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the docs mention this

It is recommended to turn on interpolation for the main character but disable it for everything else.
which means that it may behave weirdly otherwise

twilit idol Aug 3, 2020, 12:05 AM

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Everything is turned on. It works when the player's interpolation is off, but it doesn't matter when anything else is.

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and if I turn the interpolation off that leads me back to my previous problem of the game moving stuttery

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I was maybe thinking of having it to where if the player is parented under the platform it'll turn off interpolation?

opaque siren Aug 3, 2020, 1:51 AM

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I have interpolation on my player and platforms and my player doesn't have that issue, how are you moving the platforms and player?

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@twilit idol

twilit idol Aug 3, 2020, 2:31 AM

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for player I do:
rigidbody.velocity = new vector2 (PlayerInput * runspeed , rigidbody.velocity.y)

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for platforms I use transform.position = vector3.movetowards

opaque siren Aug 3, 2020, 2:32 AM

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I do the same thing

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Player:

📎 unknown.png

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Platform:

📎 unknown.png

twilit idol Aug 3, 2020, 2:33 AM

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my platforms are kinematic, I might see if that changes anything

opaque siren Aug 3, 2020, 2:34 AM

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I just made mine kinematic and it didn't change anything

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I assume there's no friction on the platforms, right?

twilit idol Aug 3, 2020, 2:35 AM

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nah

opaque siren Aug 3, 2020, 2:37 AM

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are you using built in gravity?

twilit idol Aug 3, 2020, 2:37 AM

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maybe? Can you explain

opaque siren Aug 3, 2020, 2:38 AM

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does your player move down because you are making it move down in the code or because its gravityScale is set to something

twilit idol Aug 3, 2020, 2:39 AM

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gravity scale

opaque siren Aug 3, 2020, 2:39 AM

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I don't see any difference between my platforms and yours

twilit idol Aug 3, 2020, 2:40 AM

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I'd assume it's something in the way the colliders interact inbetween frames?

opaque siren Aug 3, 2020, 2:40 AM

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are you moving the platforms and the player in FixedUpdate()?

twilit idol Aug 3, 2020, 2:41 AM

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damn I think that might be it my platforms are in regular update

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lemme check

opaque siren Aug 3, 2020, 2:42 AM

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If so then thats probably it

twilit idol Aug 3, 2020, 2:58 AM

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nope

stuck bay Aug 3, 2020, 3:47 AM

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why aren't these sticks falling

📎 unknown.png

hollow echo Aug 3, 2020, 3:48 AM

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because you've marked them as kinematic

stuck bay Aug 3, 2020, 3:49 AM

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oh yikes

twilit idol Aug 3, 2020, 8:46 PM

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I fixed the platforms! It was an issue with FixedUpdate ty @opaque siren!

hardy gale Aug 3, 2020, 11:53 PM

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is there any built-in way in Unity to do a simple box raycast without any colliders/GameObjects/components?

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I have a ray, and want to check if box at given position with given size will be in path of the ray

brazen whale Aug 4, 2020, 12:01 AM

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Can anyone tell me why mesh colliders behave as if the collider is only at the edges of the mesh?

example: i have a small box trigger-collider and a big mesh collider in the shape of a box. When the small trigger box moves into the big mesh collider box, OnTriggerEnter gets called immediately when the boxes touch, but as soon as the small box is completely inside the big box, OnTriggerExit is called.

This is fixed by setting the mesh collider to convex, but this fix sadly doesn't work for me.

foggy rapids Aug 4, 2020, 12:03 AM

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it rarely does

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what works more often is constructing your collider out of several box colliders

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if your mesh is a box, might as well use a box collider anywy

brazen whale Aug 4, 2020, 12:12 AM

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yeah sadly the box was just an example. the reason behind this is that I want do do quick blockouts with proBuilder, which automatically assigns mesh colliders
and having to build the levels collision separately would kinda defeat the purpose

foggy rapids Aug 4, 2020, 12:17 AM

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the reason it's that way is because it follows your mesh's normals.
the reason there's the convex option is to tell unity that the mesh is actually convex (solid)

brazen whale Aug 4, 2020, 12:19 AM

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sorry could you elaborate @foggy rapids? I dont understand the connection between my problem and the mesh collider being based on the meshes normals

foggy rapids Aug 4, 2020, 12:22 AM

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mesh normals specify which side of a face is the front

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if a mesh is not convex unity has no way of knowing which part is inside and which part is outside

brazen whale Aug 4, 2020, 12:30 AM

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mesh normals specify which side of a face is the front
@foggy rapids yes, that i do know, but even on a concave shape, isnt there still a clear inside and outside?

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for example with this shape in 2d, or imagine a torus in 3d. both have clear insides and outsides, as far as my understanding goes. Am I missing something?

📎 concavevsconvex2d.jpg

winged steeple Aug 4, 2020, 2:15 AM

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visually yes, but it's more work to calculate it

dusky stone Aug 4, 2020, 3:12 AM

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Okay I'm being super silly. I'm trying to enhance collision detection with rigidbodies, but the code just destroys the bullet instantly. Can someone help me please? This should be working... It always destroys the bullet even tho the ray is super small and doesn't hit anything

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    private void Update()
    {
        if(previousPosition != Vector3.zero)
        {
            float dist = Vector2.Distance(previousPosition, transform.position);
            Debug.Log(dist);
            Vector3 dir = transform.position - previousPosition;
            RaycastHit hit;
            if (Physics.Raycast(previousPosition, dir * dist, out hit, whatToHit))
            {
                if (hit.transform != transform)
                {
                    if(hit.transform.gameObject.GetComponent<Rigidbody>() != null)
                    {
                        //Add Force to GameObject
                        Vector3 _dir = hit.point - startPos;
                        Vector3 force = rb.velocity.sqrMagnitude * _dir.normalized * forceMultiplier;
                        hit.transform.gameObject.GetComponent<Rigidbody>().AddForce(force);
                    }
                    Debug.DrawRay(previousPosition, dir * 100f, Color.red);
                    Debug.Log("Hit: " + hit.transform.name);
                    Debug.Log("Destoying self because I hit: " + hit.transform.name);
                    Destroy(gameObject);
                }
            }
        }
    }

undone lynx Aug 4, 2020, 6:53 AM

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@brazen whale think of convex as shapes where

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if you draw a line passing thru the shape

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the line will only be inside the shape once

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in that picture u sent, on the concave shape, u could draw a line that passes thru it, and goes outside it, and back inside

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📎 unknown.png

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convex shapes, u can think of as "closed", in this way

willow vortex Aug 4, 2020, 11:17 AM

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@dusky stone what does the log say exactly? also you should move that to FixedUpdate() so it can raycast as it travels, and not raycast between rendered frames where it just does nothing most of the time depending on FPS.

hidden comet Aug 4, 2020, 3:38 PM

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Hey, i have a problem, i want to build a aracetrack with modular parts, but on the edge between the tiles, my cart starts jumping. Does someone have an idea hof to fix this?

📎 Project_Cart_-_Racetrack_-_PC_Mac__Linux_Standalone_-_Unity_2020.1.0f1___DX11__2020-08-04_17-37-22.mp4

foggy rapids Aug 4, 2020, 3:41 PM

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combine the meshes

hidden comet Aug 4, 2020, 3:41 PM

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how can i do that?

foggy rapids Aug 4, 2020, 3:41 PM

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it's pretty complicated. https://docs.unity3d.com/ScriptReference/CombineInstance.html

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I put a script and a mesh renderer and a mesh filter on the parent of all my pieces and put this script on it:
https://hatebin.com/yosovqyfal

hidden comet Aug 4, 2020, 3:43 PM

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hmm, shouldnt there be a easier way?

foggy rapids Aug 4, 2020, 3:43 PM

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load the whole track at once

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move the next piece slightly lower than the one you're on

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all of unity physics has this problem where colliders dont work well when tiled

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the best solution is to use one collider/mesh so the closer you can get to that the better

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or dont use colliders 😄

hidden comet Aug 4, 2020, 3:45 PM

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haha, thats the way to go i think^^

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didnt they added a new way for implementing physics?

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havok

foggy rapids Aug 4, 2020, 3:46 PM

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yeah, havok has it's own set of problems though. try both 😄

loud moon Aug 4, 2020, 3:52 PM

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Is a rigid bodies force against another spread out amongst its child colliders?

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Aka a pinky only touching the surface would have force = 10, where two fingers the force would be spread out or something?

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I have a jointed drawer with limits, and if i touch it only with my physics based hand's pinky it stretches beyond the limit, but if I hit it with more than one finger or with the entire hand it doesn't move.

brazen whale Aug 4, 2020, 6:31 PM

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@hidden comet https://catlikecoding.com/unity/tutorials/movement/surface-contact/

Surface Contact

A Unity Movement tutorial about refining how a sphere interacts with surfaces.

unborn narwhal Aug 4, 2020, 7:30 PM

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Hello, floating point operation results differ on different CPUs/GPUs and their architectures. Does the same hold for int operations as well? I'm curious whether writing deterministic physics and using a GPU to calculate the data is possible.

rain tiger Aug 4, 2020, 7:34 PM

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I'm trying to make a bouncy ball in 2D, but the PhysicsMaterial2D asset doesn't show up in my Create dropdown. Am I missing something?

foggy rapids Aug 4, 2020, 8:15 PM

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try it on the devices you want to use and see. As far as I know cpu floating point operations depend on the architecture and compiler.
These days most languages implement the same ruleset for floating point operations though. For example if you compile a c# program and a go program on the same computer then their floating point operations will be deterministic.

rugged rose Aug 5, 2020, 12:09 AM

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hey so 2D question: why does this weird gap happen on every one of my 2D projects ? The colliders are setup perfectly but the two GameObjects just don't seem to want to get any closer (for reference, the gap is just a bit more than .017f in height

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📎 unknown.png

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(the red box is just a debug tool to represent the ground check)

muted widget Aug 5, 2020, 12:58 AM

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hello

hidden comet Aug 5, 2020, 5:09 AM

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@brazen whale Thank you very much, i will try this later today

stuck bay Aug 5, 2020, 9:22 AM

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hi

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anyone know how to control a softbody with nvidia flex

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or possibly other softbody plugins?

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I tried using the chracter contoller that built-in in unity

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but it didn't work

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only works for the rigid body

rancid matrix Aug 6, 2020, 11:48 AM

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hi

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guys do you know how do I do such this free fall

📎 shopping_sort_lvl_2.mp4

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at step 2

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stacking pill

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I've changed gravity scale but it doesnt affect

upbeat dirge Aug 6, 2020, 4:21 PM

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https://twitter.com/spikebor_comic/status/1291407684718059520
i've tried everything but no setting in configurable joint can let me make the chain intact

Spikebor 🍑 (@spikebor_comic)

How to make my #unity3d chain not panik🤣? https://t.co/YVQlf6VLv1

▶ Play video

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my chain be panik and kind of rubber : ((

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i posted the joint setting in that same twitter thread, someone help pls

inland rover Aug 6, 2020, 4:31 PM

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Im Working on a vr game, and have some problems with the hand physics. Ive found my exact problem here-https://answers.unity.com/questions/1680761/rigidbody-moveposition-lags-behind-another-rigidbo.html However i am not sure how exactly to do this.

        pos = dir.normalized * dir.magnitude * forceAmount;
        this.GetComponent<Rigidbody>().AddForce(pos);```

my hands use this^ to bring the model position to the hand transform, and use a configurable joint for rotation.
They do not pass through walls, or objects, but when I move the player, they lag behind. The player has a rigidbody for control, and the hands also have rigidbodies.

RigidBody MovePosition lags behind another RigidBody - Unity Answers

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.

dusk token Aug 6, 2020, 5:28 PM

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When the F key is pressed, this getter is accessed to detect an interactable in front of the player. I've made the Raycast distance a large number for testing purposes, the thing I want to interact with

public Interactable GetInteractable
    {
        get
        {
            Vector2 dir = Vector2.zero;
 
            if (direction == Direction.up)
                dir = Vector2.up;
 
            RaycastHit2D rh = Physics2D.Raycast(body.position, dir, 3000, 8); // rh is always null
            if (rh.collider != null)
            {
                return rh.collider.gameObject.GetComponent<Interactable>();
            }

            return null;
        }
    }

The thing I want to interact with is on Layer 8 as is seen here
For some reason, it is not intersecting my raycast.

https://cdn.discordapp.com/attachments/497874004401586176/740982979148644363/unknown.png

At the top is the NPC I want to interact with, and below is the player
https://cdn.discordapp.com/attachments/497874004401586176/740983029563916348/unknown.png

sterile horizon Aug 7, 2020, 12:27 AM

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How can I make a ball bounce forever without losing or gaining height? If both colliders are at .9 bounciness the ball eventually stops bouncing, but if they're both at 1, the ball bounces higher and higher each time

graceful meadow Aug 7, 2020, 1:21 AM

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does it work if the ball is at 1 bounciness and nothing else is?

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also imprecisions might cause problems in the long run

foggy rapids Aug 7, 2020, 1:39 PM

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animation 😄

amber kettle Aug 7, 2020, 1:46 PM

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When i apply box collider to object it changes center of mass of object, any help...

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i need them same

foggy rapids Aug 7, 2020, 1:47 PM

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the center of the box should be where you want center of mass to be

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if there are multiple colliders it choose a point in the middle of all of them

naive gust Aug 7, 2020, 2:27 PM

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how do i uhh

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like weld a thing

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to a thing

foggy rapids Aug 7, 2020, 2:55 PM

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make them children of the same parent, set their local position, then only move the parent.
you can use physics joints if it has a rigidbody

naive gust Aug 7, 2020, 2:59 PM

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r

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okay uhh

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im getting an error

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📎 unknown.png

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📎 unknown.png

frigid pier Aug 7, 2020, 3:02 PM

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your entire array is null and you are testing for an element

naive gust Aug 7, 2020, 3:02 PM

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well

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exactly

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trying to check if theres something in it

frigid pier Aug 7, 2020, 3:03 PM

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check if it returns an array in the first place

naive gust Aug 7, 2020, 3:03 PM

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it does probably

foggy rapids Aug 7, 2020, 3:07 PM

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lol

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if (LGRAB && LGRAB[0] != null)

inland rover Aug 7, 2020, 3:08 PM

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Anyone know what causes physics objects to lag behind others when moving? I have a VR game and am working on physics for hands, they work until I move with my physics player, which causes them to lag behind the player.

frigid pier Aug 7, 2020, 3:10 PM

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I think it wouldn't be null, yea, but with 0 elements. do LGRAB.Length !=0 check

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@naive gust

naive gust Aug 7, 2020, 3:13 PM

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📎 unknown.png

frigid pier Aug 7, 2020, 3:16 PM

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If you need a safe test for any item check the length

naive gust Aug 7, 2020, 3:18 PM

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thingy.length > 0

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?

frigid pier Aug 7, 2020, 3:19 PM

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yes

naive gust Aug 7, 2020, 3:28 PM

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doesnt work

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it just

📎 unknown.png

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apparently doest detect it

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doesnt

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oh wait

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somehow works now

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okay so

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which constraint should i use for grabbing

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like attach it to an arm

frigid pier Aug 7, 2020, 3:31 PM

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If you are moving objects with non-physics methods or in Update instead of FixedUpdate, their colliders might not be updated properly, and could miss collisions completely

naive gust Aug 7, 2020, 3:32 PM

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what constraint should i use

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to grab

frigid pier Aug 7, 2020, 3:33 PM

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depends on what you are trying to do. You can use hinges or set object to kinematic and parent it

naive gust Aug 7, 2020, 3:38 PM

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im trying to like

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teleport it to the arms grab point

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and make sure it moves with it

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how would i do that

naive gust Aug 7, 2020, 4:30 PM

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oh no

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i have a problem

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setting iskinematic of a rigidbody to true works but

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i cant change it to false

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📎 unknown.png

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that works

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but not

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📎 unknown.png

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pinpointed the issue

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seems like

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e

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is not working

📎 unknown.png

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seems like grabbedobject is always null even though i set it

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📎 unknown.png

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📎 unknown.png

carmine robin Aug 7, 2020, 6:52 PM

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What are some common concepts for managing a maximum speed in hyper simple movement code? I've been browsing some examples to see if I can learn, but almost all of them simply end up adding force and don't care about clamping the speed.

At the very least, how do you guys recommend keeping track of the speed of a given object? I can go from there, but I'm still learning what all tools Unity offers.

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Ah, I just learned of rigidbody.velocity. All my problems are solved, haha

foggy rapids Aug 7, 2020, 7:35 PM

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this what i do:

        rb.velocity += acceleration;

        if (rb.velocity.sqrMagnitude > (maxSpeed * maxSpeed))
        {
          rb.velocity = Vector3.ClampMagnitude(rb.velocity, maxSpeed);
        }

carmine robin Aug 7, 2020, 9:11 PM

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So you add to the velocity directly rather than applying force from a certain direction, hmm

foggy rapids Aug 7, 2020, 9:12 PM

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i integrate the direction into my acceleration

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but adding forces is the same just skip the +=

carmine robin Aug 7, 2020, 9:12 PM

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Ah, so acceleration and velocity both contain a vector3, if I understand it right?

foggy rapids Aug 7, 2020, 9:12 PM

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and actually i dont even use unity physics hehe

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yes

carmine robin Aug 7, 2020, 9:13 PM

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I see

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So theoretically, if I have a floaty vehicle traveling forward and I want turning to feel a little more proper, I could make direct adjustments to rb.velocity to shift the momentum, as opposed to using... I guess newtonian forces

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C# is a lot more powerful than what I'm used to, having this amount of control is a little overwhelming, but it's fascinating.

stuck bay Aug 7, 2020, 9:31 PM

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This might sound like a very dumb question, but why isnt my player colliding with the ground?

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Player:

📎 unknown.png

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Ground:

📎 unknown.png

foggy rapids Aug 7, 2020, 9:38 PM

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ground needs rigidbody too