How to specify indices for normals, texture coordinates, and others, separately?

[zeman-88]

I would like to specify the indices for other attributes other than the "point" ones.

I.e.: if I have N positions, and M normals, the indices for the normals for that Mesh are different from the ones for the positions.
Hence a call to CreateFaceVertexIndicesAttr won't cut it, as that only specifies the indices as if all the attributes for a vertex follow the same indexing.

Take this Mesh as an example:

    def Mesh "geometry15"
    {
        float3[] extent = [(-0.5, -0.5, -0.5), (0.5, 0.5, 0.5)]
        int[] faceVertexCounts = [3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3]
        int[] faceVertexIndices = [0, 3, 1, 0, 2, 3, 4, 7, 5, 4, 6, 7, 8, 11, 9, 8, 10, 11, 12, 15, 13, 12, 14, 15, 16, 19, 17, 16, 18, 19, 20, 23, 21, 20, 22, 23]
        rel material:binding = </material5>
        normal3f[] normals = [(0, 0, 1), (0, 0, 1), (0, 0, 1), (0, 0, 1), (1, 0, -4.37114e-8), (1, 0, -4.37114e-8), (1, 0, -4.37114e-8), (1, 0, -4.37114e-8), (-8.74228e-8, 0, -1), (-8.74228e-8, 0, -1), (-8.74228e-8, 0, -1), (-8.74228e-8, 0, -1), (-1, 0, 1.19249e-8), (-1, 0, 1.19249e-8), (-1, 0, 1.19249e-8), (-1, 0, 1.19249e-8), (0, 1, -4.37114e-8), (0, 1, -4.37114e-8), (0, 1, -4.37114e-8), (0, 1, -4.37114e-8), (0, -1, -4.37114e-8), (0, -1, -4.37114e-8), (0, -1, -4.37114e-8), (0, -1, -4.37114e-8)]
        point3f[] points = [(-0.5, -0.5, 0.5), (-0.5, 0.5, 0.5), (0.5, -0.5, 0.5), (0.5, 0.5, 0.5), (0.5, -0.5, 0.5), (0.5, 0.5, 0.5), (0.5, -0.5, -0.5), (0.5, 0.5, -0.5), (0.5, -0.5, -0.5), (0.5, 0.5, -0.5), (-0.5, -0.5, -0.5), (-0.5, 0.5, -0.5), (-0.5, -0.5, -0.5), (-0.5, 0.5, -0.5), (-0.5, -0.5, 0.5), (-0.5, 0.5, 0.5), (-0.5, 0.5, 0.5), (-0.5, 0.5, -0.5), (0.5, 0.5, 0.5), (0.5, 0.5, -0.5), (-0.5, -0.5, -0.5), (-0.5, -0.5, 0.5), (0.5, -0.5, -0.5), (0.5, -0.5, 0.5)]
        texCoord2f[] primvars:st = [(0, 0), (0, 1), (1, 0), (1, 1), (0, 0), (0, 1), (1, 0), (1, 1), (0, 0), (0, 1), (1, 0), (1, 1), (0, 0), (0, 1), (1, 0), (1, 1), (0, 0), (0, 1), (1, 0), (1, 1), (0, 0), (0, 1), (1, 0), (1, 1)] (
            interpolation = "faceVarying"
        )
        int[] primvars:st:indices = [0, 3, 1, 0, 2, 3, 4, 7, 5, 4, 6, 7, 8, 11, 9, 8, 10, 11, 12, 15, 13, 12, 14, 15, 16, 19, 17, 16, 18, 19, 20, 23, 21, 20, 22, 23]
        uniform token subdivisionScheme = "none"
    }

what if I wanted to have a different number of normals from the vertices and specify their indexing differently? I would like to achieve something like this:

    def Mesh "geometry15"
    {
        float3[] extent = [(-0.5, -0.5, -0.5), (0.5, 0.5, 0.5)]
        int[] faceVertexCounts = [3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3]
        int[] facePositionIndices = [0, 3, 1, 0, 2, 3, 4, 7, 5, 4, 6, 7, 8, 11, 9, 8, 10, 11, 12, 15, 13, 12, 14, 15, 16, 19, 17, 16, 18, 19, 20, 23, 21, 20, 22, 23]
        // Here I am changing the numbers at random to explain the concept
        int[] faceNormalIndices = [0, 2, 1, 0, 3 10, 5, 10, 5, 4, 6, 7, 8, 11, 9, 8, 10, 11, 12, 15, 13, 12, 14, 15, 16, 19, 17, 16, 18, 19, 20, 23, 21, 20, 22, 23]
        rel material:binding = </material5>
        normal3f[] normals = [(0, 0, 1), (0, 0, 1), (0, 0, 1), (0, 0, 1), (1, 0, -4.37114e-8), (1, 0, -4.37114e-8), (1, 0, -4.37114e-8), (1, 0, -4.37114e-8), (-8.74228e-8, 0, -1), (-8.74228e-8, 0, -1), (-8.74228e-8, 0, -1), (-8.74228e-8, 0, -1), (-1, 0, 1.19249e-8), (-1, 0, 1.19249e-8), (-1, 0, 1.19249e-8), (-1, 0, 1.19249e-8), (0, 1, -4.37114e-8), (0, 1, -4.37114e-8), (0, 1, -4.37114e-8), (0, 1, -4.37114e-8), (0, -1, -4.37114e-8), (0, -1, -4.37114e-8), (0, -1, -4.37114e-8), (0, -1, -4.37114e-8)]
        point3f[] points = [(-0.5, -0.5, 0.5), (-0.5, 0.5, 0.5), (0.5, -0.5, 0.5), (0.5, 0.5, 0.5), (0.5, -0.5, 0.5), (0.5, 0.5, 0.5), (0.5, -0.5, -0.5), (0.5, 0.5, -0.5), (0.5, -0.5, -0.5), (0.5, 0.5, -0.5), (-0.5, -0.5, -0.5), (-0.5, 0.5, -0.5), (-0.5, -0.5, -0.5), (-0.5, 0.5, -0.5), (-0.5, -0.5, 0.5), (-0.5, 0.5, 0.5), (-0.5, 0.5, 0.5), (-0.5, 0.5, -0.5), (0.5, 0.5, 0.5), (0.5, 0.5, -0.5), (-0.5, -0.5, -0.5), (-0.5, -0.5, 0.5), (0.5, -0.5, -0.5), (0.5, -0.5, 0.5)]
        texCoord2f[] primvars:st = [(0, 0), (0, 1), (1, 0), (1, 1), (0, 0), (0, 1), (1, 0), (1, 1), (0, 0), (0, 1), (1, 0), (1, 1), (0, 0), (0, 1), (1, 0), (1, 1), (0, 0), (0, 1), (1, 0), (1, 1), (0, 0), (0, 1), (1, 0), (1, 1)] (
            interpolation = "faceVarying"
        )
        int[] primvars:st:indices = [0, 3, 1, 0, 2, 3, 4, 7, 5, 4, 6, 7, 8, 11, 9, 8, 10, 11, 12, 15, 13, 12, 14, 15, 16, 19, 17, 16, 18, 19, 20, 23, 21, 20, 22, 23]
        uniform token subdivisionScheme = "none"
    }

How can I specify different indices for different attributes of a vertex for a mesh?

[zeman-88]

I can answer this for myself, as I was already doing it for the texture coordinates: create a Primvar manually and assign it its own indices manually, like it's done for texture coordinates.

[spiffmon]

Yes! In what likely was a poor decision, we made “normals” (and widths) be builtin schema attributes that are *not* primvars, so they cannot be indexed. However, before even checking for authored *normals* on a Mesh, Hydra will look for *primvars:normals*, and that can be indexed like all other primvars.

On Sun, Nov 25, 2018 at 6:54 PM zeman-88 ***@***.***> wrote: Closed #706 <#706>. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#706 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AF7qaBPgUwzyAgmyXEX79Rnrr3kEQtczks5uy1f-gaJpZM4YyOgn> .

-- --spiffiPhone