UV of Float32x3 causes GPU buffer issue in 0.6.0 (works fine in 0.5.0)

[WAFFO]

Bevy version

Release 0.6.0

Operating system & version

Tested: Windows 10, MacOS 12.1

What you did

Follow duplication steps in https://github.com/WAFFO/bevy_0.6.0_mesh_issue

I originally ran into this issue migrating my project and encountered a computer killing monster where my heightmap mesh once was. (Pictured below)

This was OS breaking, and I had to hold my power button to escape.

What you expected to happen

To draw a flat square made of two triangles, 4 vertices. (Pictured: 0.5.0)

What actually happened

One triangle, standing. (Pictured: Same mesh code in 0.6.0)

Additional information

If the mesh is really big (like for a heightmap) my computer comes to a halt and I have to hold the power button to reset. I suspect something is not aligned in the GPU buffer.

The Culprit!

It's this line here: https://github.com/WAFFO/bevy_0.6.0_mesh_issue/blob/v6/src/main.rs#L83

let uvs = vec![[0.0, 0.0, 0.0]; vertices.len()];

Change it from a [f32; 3] to a [f32; 2]

let uvs = vec![[0.0, 0.0]; vertices.len()];

And now it works perfectly!

This shouldn't be allowed to happen :(

It took a long time for me to figure out why my mesh was breaking in 0.6.0.

Since it worked in 0.5.0, I have to ask if it's intended for [f32; 3] to not work for the UV attribute. If so, a type check or some error is needed. Otherwise, it's a bug!

[ruabmbua]

Nice find. This also killed my voxel renderer!
Very confusing to debug, since I also had reduced it to one plane, and it generated a standing triangle, which should be impossible, because I did not have any varying vertex in y-plane.

[sdfgeoff]

Same issue occurs if UV attribute does not exist.

[sdfgeoff]

Same issue occurs if TANGENT attribute is not a vec4

[mockersf]

should be fixed by #3959

[cart]

Kind of sort of. That enables flexible layouts, but it also standardizes the formats of specific vertex attributes. Mesh::ATTRIBUTE_POSITION must be a vec3. Mesh::ATTRIBUTE_UV_0 must be a vec2. This is because shaders expect specific attributes / sizes.

Users are free to create a new "three dimensional" UV attribute and use that in their custom shaders with custom meshes. They can even use that in our built in shaders (provided they also provide a 2d UV attribute). But we cant (and won't) allow using three dimensional uvs in places where our core shaders expect two dimensional uvs. Same goes for all of the "core" vertex attributes defined on Mesh.

[cart]

I guess "can't" and "won't" are strong words. I'm open to discussing solutions to specific scenarios.