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The mapbox earcut library returns triangles in clockwise winding order, but USD expects counter-clockwise order. This was causing reversed face orientation for polygons with 5 or more vertices when using the earcut triangulation method. Changes: - src/tydra/render-data.cc: Reverse triangle winding order by swapping indices 1 and 2 when processing earcut results to convert from CW to CCW - examples/tydra_to_renderscene/to-renderscene-main.cc: Add --trifan option to enable triangle fan triangulation method for testing The triangle fan method was already producing correct CCW triangles and did not require changes. Tested with models/ngon.usdc containing pentagon, hexagon, and octagon. Both triangulation methods now correctly produce CCW triangles. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>
Synthetic Test Environment Maps
This directory contains synthetic environment maps in long-lat (equirectangular) format for testing purposes. All images are 128x64 HDR format (.hdr files using Radiance RGBE encoding).
Generated Files
RGB Axis Environment Map
- env_synthetic_rgb_axes.hdr
- +X direction: Red
- +Y direction: Green
- +Z direction: Blue
- -X, -Y, -Z directions: Black
- Useful for testing coordinate system orientation and color channels
Hemisphere Environment Map
- env_synthetic_hemisphere_upper_white.hdr
- Upper hemisphere (+Y > 0): White
- Lower hemisphere (+Y <= 0): Black
- Useful for testing hemisphere lighting and ground plane interactions
Single-Face White Environment Maps
Each of these maps has white color on one cube face direction, and black on all others:
- env_synthetic_pos_x_red.hdr - White on +X face only
- env_synthetic_neg_x.hdr - White on -X face only
- env_synthetic_pos_y_green.hdr - White on +Y face only
- env_synthetic_neg_y.hdr - White on -Y face only
- env_synthetic_pos_z_blue.hdr - White on +Z face only
- env_synthetic_neg_z.hdr - White on -Z face only
These are useful for testing individual cube face contributions and verifying environment map sampling directions.
Generation
To regenerate these environment maps:
cd models/textures/test-envs
node generate_synthetic_envmaps.js
Technical Details
- Format: Radiance RGBE HDR (.hdr)
- Resolution: 128x64 pixels
- Projection: Long-lat (equirectangular)
- File size: ~33 KB per file
- Color space: Linear (no gamma correction)
Usage in Testing
These synthetic environment maps are ideal for:
- Verifying MaterialX environment shader implementations
- Testing IBL (Image-Based Lighting) rendering
- Debugging coordinate system transformations
- Validating cube map sampling and lookups
- Checking color channel assignments