Implement support for ND_open_pbr_surface_surfaceshader exported by Blender v4.5
when using MaterialX. This enables proper parsing and conversion of OpenPBR
materials from Blender-exported USD files.
Key changes:
- Add MtlxOpenPBRSurface struct with all Blender v4.5 parameters in usdMtlx.hh
- Implement ReconstructShader specialization for MtlxOpenPBRSurface in prim-reconstruct.cc
- Add MaterialXConfigAPI detection and OpenPBR shader attachment in render-data.cc
- Implement DumpOpenPBRSurface for material output in render-scene-dump.cc
- Add pretty-print support for MtlxOpenPBRSurface in pprinter.cc
When MaterialXConfigAPI is present on a Material, the system now:
1. Attempts to parse outputs:mtlx:surface connection
2. Falls back to searching for child Shader prims with OpenPBR info:id
3. Converts MtlxOpenPBRSurface to OpenPBRSurface for rendering
Tested with models/cube-materialx.usda and models/suzanne-materialx.usda
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
