Syoyo Fujita 2aeac6eb28 Fix reverse face orientation in Tydra earcut triangulation for 5+ gons ...

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>

2025-11-20 11:14:43 +09:00

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