Vertex normals

[kylebarron]

Optionally compute vertex normals extension. There's two parts:

Normal Generation

Based on the quantized-mesh-tile implementation, essentially for every vertex you look at all the triangles that touch it. For each triangle, compute its normal, and then average the normals of the touching triangles to find each per-vertex normal.

I think that to make it performant, you'd want to first compute all the normals of the triangles. And then you can use that array of normals somehow as a lookup table, so that you can find all the triangles per vertex at once, and then average within the axis...

Normal Encoding

Quantizing and encoding each x, y, z 96-bit floating point unit vector into an x,y 16-bit representation.

References

• Spec
• Quantized mesh tile generation
• Encoding technique paper

[kylebarron]

Closed by #35 and #18