fix: preserve vertex attributes with smooth normals

[Srinidhi444]

Resolves #9205

Changes:

• Fixed computeNormals(SMOOTH) so it no longer permanently deduplicates geometry vertices based only on position.
• Smooth normals are calculated using temporary position-based vertex groups and then mapped back to the original vertices.
• This preserves per-vertex attributes such as UVs while still allowing vertices at the same position to share smooth normals.
• Added a unit test covering vertices with the same position but different UV coordinates.

Screenshots of the change:

PR Checklist

• npm run lint passes
• Inline reference is included / updated
• Unit tests are included / updated

[p5-bot]

Continuous Release

CDN link

• https://raw.esm.sh/pr/p5@4bae8cb/lib/p5.min.js

Published Packages

• https://pkg.pr.new/p5@4bae8cb

Commit hash: 4bae8cb

Previous deployments

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This is an automated message.

[davepagurek]

Logic looks good! To confirm that the normals themselves haven't changed since before, would you be up for adding a visual test with maybe normalMaterial() on a shape with computeNormals(SMOOTH) applied so that we can more easily visually inspect it? If you need some example geometry, there's an example sketch in the "smooth shading" section of https://p5js.org/tutorials/custom-geometry/ that we could borrow.

[davepagurek]

Nice!

[Srinidhi444]

Logic looks good! To confirm that the normals themselves haven't changed since before, would you be up for adding a visual test with maybe normalMaterial() on a shape with computeNormals(SMOOTH) applied so that we can more easily visually inspect it? If you need some example geometry, there's an example sketch in the "smooth shading" section of https://p5js.org/tutorials/custom-geometry/ that we could borrow.

Logic looks good! To confirm that the normals themselves haven't changed since before, would you be up for adding a visual test with maybe normalMaterial() on a shape with computeNormals(SMOOTH) applied so that we can more easily visually inspect it? If you need some example geometry, there's an example sketch in the "smooth shading" section of https://p5js.org/tutorials/custom-geometry/ that we could borrow.

sure

[Srinidhi444]

Logic looks good! To confirm that the normals themselves haven't changed since before, would you be up for adding a visual test with maybe normalMaterial() on a shape with computeNormals(SMOOTH) applied so that we can more easily visually inspect it? If you need some example geometry, there's an example sketch in the "smooth shading" section of https://p5js.org/tutorials/custom-geometry/ that we could borrow.

hey @davepagurek added the requested visual test for computeNormals(SMOOTH) using normalMaterial() on the warped tube geometry from the smooth shading example.
The visual test passes and the expected screenshot has been generated pls check it and let me know if any issues