Collision Issue

[SpiderPig]

Haven't had time to put together an example yet, but here's a video of the issue and the collider I'm using is attached as well as the .obj it was generated from.  This has been happening since the fix for Mesh Colliders.  Before then this shape didn't work at all.  The video is just a player controller getting stuck inside this collider and when it does collide, it jitters a lot.

 

Physics.zip

[Josh]

It appears to be loading correctly.

Maybe the faces are all backwards, either in the shape, or they could be getting flipped in my loader...

[SpiderPig]

Good point, they might be backwards - I'll check...

[Josh]

It looks like the top and bottom have the opposite orientation as the sides, although I can't say for sure which is right. Maybe the physics system has a different handedness than the renderer...

[SpiderPig]

Yeah these are the normals shown in blender, they appear correct.  I might remove the top and bottoms caps, although I don't know what that means if something does collide at the top or bottom...

[Josh]

Okay, I fixed a bug in the OBJ loader that was flipping some faces. However, I do not know if the handedness of the physics matches the handedness of the renderer...

[SpiderPig]

What is handedness? 

[Josh]

The direction a polygon faces, given three indices in order. It can be one direction or the other.

[SpiderPig]

Oh right, I thought it was called winding.

[Josh]

I'm assuming that's the problem. I just uploaded an update that flips the direction of faces in mesh colliders.

[SpiderPig]

Just confirming that seems to have fixed it, thanks.

[SpiderPig]

I'm not sure if the flip of faces for mesh colliders was right or not.

This is the order I add vertices.  It's the exact same order as I use for rendering.  3 vertices per face.  If I reverse the order I add these vertices the collision works, I just want to confirm that this is how things should be before I make changes to my code?

collision_patch->AddVertex(p[0].x - position_offset.x, p[0].y - position_offset.y, p[0].z - position_offset.z);
collision_patch->AddVertex(p[1].x - position_offset.x, p[1].y - position_offset.y, p[1].z - position_offset.z);
collision_patch->AddVertex(p[2].x - position_offset.x, p[2].y - position_offset.y, p[2].z - position_offset.z);

All those vertices are added to a vector in order and I build a mesh collider like this;  I could just reverse the order here too, but still, just checking.

vector<vector<Vec3>> faces;
auto total_faces = vertices.size() / 3;
faces.resize(total_faces);
int id = 0;
for (int f = 0; f < total_faces; f++) {
	vector<Vec3> v;
	v.reserve(3);
	v.emplace_back(vertices[id]);
	v.emplace_back(vertices[id + 1]);
	v.emplace_back(vertices[id + 2]);
	faces[f] = v;
	id += 3;
}

collider = CreateMeshCollider(faces);