feat: add color-attribute-wheel example#54
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Witnesses the modern color-attributes API (mesh.color_attributes.new on the CORNER domain) that AI code routinely swaps for the deprecated vertex_colors alias, and the domain-size trap that follows: a CORNER attribute is sized to loop count, not vertex count, so per-vertex data must be expanded across face corners before writing. Also asserts the Attribute node is actually linked to Base Color, since AI code frequently creates the attribute but forgets to wire it into the shader.
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Summary
examples/color-attribute-wheel/— an HSV color wheel disc built withbmesh, colored via the modernMesh.color_attributes.new()API (not the deprecatedvertex_colorsalias).CORNER-domainFLOAT_COLORattribute is sized tolen(mesh.loops), notlen(mesh.vertices)— a domain-size trap AI-generated code hits when it assumes per-vertex sizing. Per-vertex HSV is expanded across face corners with oneforeach_get(loop → vertex index) + oneforeach_set(loop color). The check also assertscolor_attributes.active_colorpoints at it, and that the shaderAttributenode (attribute_type='GEOMETRY') is actually linked to Base Color — a step AI code frequently skips, leaving the mesh gray even though the attribute data is correct.examples/gallery.jsonentry,.cursor-plugin/plugin.jsonexamples array,blender-smoke.ymlcheck-only step (both 4.5 LTS and 5.1), README gallery row + aggregate counts (14 → 15), AGENTS.md/CLAUDE.md example counts, hero/preview webp assets, regenerateddocs/gallery/.Visual notes
Rendered with both EEVEE and Cycles locally (portable Blender 5.1.2 and 4.5.11 LTS on Windows) — pixel-identical composition across engines and Blender versions. Key fix during iteration: Blender's default AgX view transform compresses bright regions toward white, which was hiding the saturation gradient this example exists to show off; the render path now explicitly sets
view_transform = 'Standard'so the rendered colors match the underlying attribute data. Framing uses aTRACK_TOaim empty (matching theswatch-gridlight-aim convention) rather than hand-tuned camera rotation, tilted gently so the disc reads as a wheel rather than foreshortening into an ellipse-dominated shape, on the repo's usual dark-studio floor/wall/three-light rig.Test plan
blender --background --python color_attribute_wheel.py --exits 0 on Blender 5.1.2 (portable, local)--outputrender verified on both engines (EEVEE, Cycles) and both Blender versions; hero/preview pixels visually inspected at full size and thumbnail croppython scripts/build_gallery.pyregenerateddocs/gallery/cleanlyvalidate-countsandvalidate-manifestCI checks passesvalidate.yml,drift-check.yml,blender-smoke.yml(4.5 + 5.1) green on this PR🤖 Generated with Claude Code