Using moveWithCollisions with imported GLTF boxes

[Sem]

For some reason, when importing meshes, the collision when using moveWithCollisions() seems to be off.

Here is an example with created boxes, which works correctly:

Babylon.js Playground

Here is an example with an imported glb file, where the moving box goes through other colliders:

Babylon.js Playground

Am I missing some kind of import settings?

[carolhmj]

cc @Cedric

[Cedric]

Let me take a look …

[Cedric]

@Sem

I think it’s relative to the mesh being double sided. Not the material but I think all the triangles are doubled?
I checked that with the inspector. Setting the material front sided faces didn’t change anything.

Try again with single sided faces and let me know if it works.

[Sem]

@Cedric Hey thanks for the response! Sadly, this is not the case. I enabled backface culling in the material and used a “merge by distance” in Blender, it did remove multiple vertices but the problem still persists.

You can see the exported GLTF cubes at https://test.zuncreative.com/col.glb

[Cedric]

I need to dig deeper. I’ll do it in the coming days.

[Sem]

Thank you so much!

I did some more fiddling around and found that scene.useRightHandedSystem = true; solves the random collision issue, so the collision might be a problem because the Z scale of the root is -1 because of the GLTF import.
movewithcollisions | Babylon.js Playground (babylonjs.com)

It still feels like the collider boxes are smaller than the meshes even though they are scale 1.

[Cedric]

Ho! good catch! it will definitely help me track the issue

[Cedric]

The issue is actually the collider(player cube mesh) is still attached to the root (with negative scale)
if you set its root to null, then everything is fine.

[carolhmj]

Hello @Sem just checking in, are you still having issues?

[Sem]

Hey, sorry for the late response. I was on holiday

When setting meshes parents to null definitely solves the issue.
I do think importing GLTF meshes in a negative scale is a fundamental problem, had multiple issues with it over the years. But I do not know the philosophy behind it.

[carolhmj]

Unfortunately we have to do it to convert between GLTF’s right handed system to our left

[Sem]

Thanks for the explanation @carolhmj and even though it might take more time to load, I’d rather have something like vertices recalculated instead of applying this negative scale.

[carolhmj]

You can use Mesh | Babylon.js Documentation (babylonjs.com) bakeCurrentTransformIntoVertices to do that

[Sem]

Hey @carolhmj , thanks so much for sharing. I’ll try this one for sure.