Mesh Attribute Position: Vec<[f32;3]> vs Vec<f32>

[afonsolage]

So I'm playing with custom Mesh creation and I noticed something odd. First I created a plane using just a Vec<f32> with all floats needed and no error was shown but nothing is rendered neither.

    let v_f32 = vec![
        -0.5, -0.5, -0.5,
        0.5, -0.5, -0.5,
        0.5, 0.5, -0.5,
        -0.5, 0.5, -0.5,
    ];
    
    let indices = vec![0, 1, 2, 2, 3, 0];
    
    let mut mesh = Mesh::new(PrimitiveTopology::TriangleList);
    mesh.set_indices(Some(Indices::U32(indices)));
    mesh.set_attribute(Mesh::ATTRIBUTE_POSITION, v_f32);
    
    commands.spawn_bundle(MeshBundle {
        mesh: meshes.add(mesh),
        render_pipelines: RenderPipelines::from_pipelines(vec![RenderPipeline::new(
            pipeline_handle,
        )]),
        ..Default::default()
    });

But after reading the examples for a while I noticed that Mesh::ATTRIBUTE_POSITION expectes a Vec<[f32;3] so after just changing the v_f32 to v_arr it worked fine:

    let v_arr = vec![
        [-0.5, -0.5, -0.5],
        [0.5, -0.5, -0.5],
        [0.5, 0.5, -0.5],
        [-0.5, 0.5, -0.5],
    ];
    
    let indices = vec![0, 1, 2, 2, 3, 0];
    
    let mut mesh = Mesh::new(PrimitiveTopology::TriangleList);
    mesh.set_indices(Some(Indices::U32(indices)));
    mesh.set_attribute(Mesh::ATTRIBUTE_POSITION, v_arr); //Vec<[f32;3]> now
    
    commands.spawn_bundle(MeshBundle {
        mesh: meshes.add(mesh),
        render_pipelines: RenderPipelines::from_pipelines(vec![RenderPipeline::new(
            pipeline_handle,
        )]),
        ..Default::default()
    });

My question is if Mesh::ATTRIBUTE_POSITION only works with Vec<[f32;3]> why it let me use Vec<f32> and no error/warning is shown? This is an intended behaviour?

I placed an example on Gist if anyone interested.

[cart]

We need to support every possible attribute value in mesh::set_attribute. The "position" attribute might expect a Vec<[f32;3]>, but the "uv" attribute expects a Vec<[f32;2]>. We accepted Vec<f32> because that is a valid attribute type (just not the right one for "position"). That being said, this should probably be a runtime warning / error. The rendering issue is probably because the shader consuming this expects a vec3 type, but the mesh is providing a float type. This is where the "mismatch" occurs and where the validation should happen. We should try to fix this in the upcoming renderer rework (slated to land in Bevy 0.6).