OpenPBR Specification correction:
- subsurface_radius: should be float type (not color3f)
- subsurface_radius_scale: should be color3f type
Changes made:
1. Updated documentation in doc/openpbr-parameters-reference.md
2. Updated doc/C++_MATERIALX_IMPORT.md with correct parameter types
3. Fixed TinyUSDZ Core schema definitions in src/usdShade.hh
4. Updated MaterialX types in src/usdMtlx.hh and src/usdMtlx.cc
5. Fixed Tydra render data types in src/tydra/render-data.hh/.cc
6. Fixed Three.js exporter in src/tydra/threejs-exporter.cc
7. Updated test comparison script
This allows openpbr-subsurface-sphere.usda and similar files to parse
without "Property type mismatch" validation errors.
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>