#Snap to grid

1 messages · Page 1 of 1 (latest)

white imp
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I'm a bit confused. Are you spawning in the plane or an object into an existing plane?

loud mountain
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Both

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The grid object which needs to be snapped is set as the child of the plane

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The plane is meant to be a guide of sorts

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It was just an idea that came to mind so I thought I'd try it.

white imp
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Are they being created at the same time? If so, why not create the plane at the origin with no rotation, instantiate the game object with the plane as the parent, also centered at the origin so it's in the middle, then move the plane to where it needs to be placed with the correct rotation?

loud mountain
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The problem is moving the plane where it needs to be

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The approach I'm trying to go for is treating any angled surface as if it were the ground and then rounding the X and Z and then aligning to the surface of the plane

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I can provide some visuals if it helps

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I don't know how much this helps

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Essentially, I need this snapping to work on any plane angle.

white imp
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Are the objects being spawned the mine sweeper tiles?

loud mountain
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Yes, sorry for the confusion I should have cleared that up

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The numbers don't need to be worried about for now, I can figure that out later

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I'm primarily focused on the snapping issue for now

white imp
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Gotcha. So a first person shooter 3D Minesweeper and you are spamming in the tiles as they are exposed?

loud mountain
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The numbers are more cosmetic for immersion. The player doesn't reveal mines, they place them and then can reveal them to explode whenever

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They act like a mine launcher i guess and you can use them to rocket jump or kill enemies

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I've been working on it for quite some time

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It's a fun project lol

white imp
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Nice, ahaha. Give me a minute and I can type up some pseudo code of how I would approach it.

loud mountain
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Awesome, I appreciate the help

white imp
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Raycast to point and get hit collider
Get the transform of the hit collider
Move the world space point of the hit to the local space of the collider using the transform
Round the local space hit position to the nearest whole unit in z and x,

from here you can take two appraoches:
instantaite the object in local space (using the local space hit point and Quaternion.Identity) and parent it using SetParent(parent, false) so it moves correctly.

or

transform the rounded local hit position back to world space and Instantiate at that point using the world hit and the same quaternion as the collider
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You shouldn't need to cross product or do any particular linear algebra if you take advantage of moving between local and world spaces

loud mountain
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Can you clarify what you mean by "Move the world space point of the hit to the local space of the collider using the transform"?

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I have the transform which I got from Transform t = collision.contacts[0].otherCollider.transform;

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would I be using InverseTransformPoint ?

white imp
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Yup, that will put you in local space so you can work relative to the hit collider rather than in world space. Since you've local to the collider, the logic becomes the same as if the collider had no rotation

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It's a pretty solid approach that's use by most things that require dealing with two objects with arbitrary transforms. If you put one local to the other, it changes the problem to a single arbitrary transform and the other is the identity, which is easier to work with and usually more performant

loud mountain
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I assume it still would, but would this still work with a probuilder mesh?

white imp
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Depends on how the collider is set up. If it's a mesh collider than the transform will always be the identity since all angles are just baked into the mesh. That means the position will work but the rotation won't but you could cheat it by setting the transform.up of your instantiated object newObject.transform.up = collision.normal;

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That will update the rotation so make up and normal aligned

loud mountain
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Wonderful news, it works for non-probuilder meshes!!

regular.PNG
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that's at least a step in the right direction!

loud mountain
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When its instantiated, should I use quaternion.identity and then change the up?

white imp
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That would work, yeah. You could also technically calculate the quaternion using the normal but setting the up afterward is easier.

loud mountain
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So i believe the position is being screwed up when the mesh isn't a plane like the image on the right

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the image on the left shows a probuilder mesh which has some modifications. the other surfaces get messed up as a result

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I think its more of a positional problem rather than rotation

white imp
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when you mention modifications, what do you mean?

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If it's been moved/rotated then you'll need to apply both approaches

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use the transform to get to local space and also use the normal to calculate the rotation. Hard to tell without seeing all the code but at a high level that should be all that is needed

loud mountain
# white imp when you mention modifications, what do you mean?

Sorry if my wording wasn't clear, I'll try to rephrase that. Let's say I built a level entirely out of one mesh with a wide assortment of surfaces in probuilder. The picture on the left shows an example of one mesh that has multiple different surfaces.

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and that doesn't work compared to the right image which is one flat surface as one mesh

white imp
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How is the collider set up in that case?

loud mountain
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It's a mesh collider

white imp
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and is the probuilder generated mesh moved/rotated after it's created?

loud mountain
white imp
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hmm, then the simpler (transform.up = collision.normal) approach should work, assuming the transform is the identity on the mesh

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You may need to get in there with the debugger to figure out where it's breaking

loud mountain
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I think I just thought of a possible solution

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Going back to the imaginary plane, I think it might be helpful in this case. A plane is placed at the position of the hit point and aligned with the normal. Then instead of using the probuilder mesh to align itself, it uses the plane

white imp
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constructing the imaginary plane is essentially the same thing as calculating the target rotation, since those things are interchangeable. You should be able to construct it without tangets and only the collision.normal

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A plane is just a point in space and a normal vector

loud mountain
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Hey! Sorry about the late response, I had to go to work. I ended up getting it to work! It works on all surfaces now regardless of whether or not its a probuilder mesh!