Handle face subsets for OBJ #52
Description
Is this a new feature, an improvement, or a change to existing functionality?
New Feature
Feature Description
OBJ/MTL supports per-face material assignment. I have attached an example cube with a different material for each face. Were this to be referenced in a URDF we should see those same face-colors via UsdGeom.Subset bindings.
Additional context or alternatives
cube.obj:
# Simple cube with 6 colored faces
mtllib cube.mtl
o color_cube
# Vertices
v -0.5 -0.5 -0.5
v 0.5 -0.5 -0.5
v 0.5 0.5 -0.5
v -0.5 0.5 -0.5
v -0.5 -0.5 0.5
v 0.5 -0.5 0.5
v 0.5 0.5 0.5
v -0.5 0.5 0.5
# Normals
vn 0 0 -1
vn 0 0 1
vn 0 -1 0
vn 0 1 0
vn -1 0 0
vn 1 0 0
# Bottom face -Z (red)
usemtl red
f 1//1 4//1 3//1 2//1
# Top face +Z (green)
usemtl green
f 5//2 6//2 7//2 8//2
# Front face -Y (blue)
usemtl blue
f 1//3 2//3 6//3 5//3
# Back face +Y (yellow)
usemtl yellow
f 4//4 8//4 7//4 3//4
# Left face -X (cyan)
usemtl cyan
f 1//5 5//5 8//5 4//5
# Right face +X (magenta)
usemtl magenta
f 2//6 3//6 7//6 6//6
cube.mtl:
# Cube materials - one color per face
newmtl red
Kd 1.0 0.0 0.0
newmtl green
Kd 0.0 1.0 0.0
newmtl blue
Kd 0.0 0.0 1.0
newmtl yellow
Kd 1.0 1.0 0.0
newmtl cyan
Kd 0.0 1.0 1.0
newmtl magenta
Kd 1.0 0.0 1.0
Code of Conduct
- I agree to follow urdf-usd-converter Code of Conduct
- I have searched the open issues and have found no duplicates