fix(BillboardCollection): Fix precision loss in billboard image texcoords

[donmccurdy]

Description

Previously a billboard's image offsetX/Y and width/height were encoded as quantized 12-bit floats (0–1) before texture sampling. For texture coordinates "in general" this might be reasonable precision, but knowing offsets into the texture atlas are integers 0–16K in practice, we can skip quantization and losslessly pack the uint16 values into the same space.

Preview:

TODO

Issue number and link

• Fixes Billboard clipped on right side #5154

Testing plan

TODO

Author checklist

• I have submitted a Contributor License Agreement
• I have added my name to CONTRIBUTORS.md
• I have updated CHANGES.md with a short summary of my change
• I have added or updated unit tests to ensure consistent code coverage
• I have updated the inline documentation, and included code examples where relevant
• I have performed a self-review of my code

PR Dependency Tree

• PR fix(textureatlas): Allocate texture space more incrementally on resize #13042
  • PR refactor(BillboardCollection): Require instancing, remove batch mode #13049
    • PR fix(BillboardCollection): Fix precision loss in billboard image texcoords #13050 👈

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[github-actions]

Thank you for the pull request, @donmccurdy!

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