vello_hybrid: fast-path premultiplied color matrices#1625
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waywardmonkeys wants to merge 4 commits into
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vello_hybrid: fast-path premultiplied color matrices#1625waywardmonkeys wants to merge 4 commits into
waywardmonkeys wants to merge 4 commits into
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This was done with the assistance of Codex (GPT 5.5, xhigh). |
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This is a draft as it builds upon PR #1623, adding an optimization present there for the CPU renderer to the Hybrid renderer. |
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This adds a
vello_hybridshader fast path for color matrices that can be applied directly in premultiplied-alpha space.For RGB-only, alpha-preserving matrices with no RGB offsets,
ColorMatrixno longer needs to unpremultiply each sampled pixel, apply the matrix in straight-alpha space, then premultiply again. Instead, hybrid marks those matrices in the encoded filter header and the shader applies the RGB rows directly to premultiplied RGB, clamps the result to[0, alpha], and preserves alpha.This covers matrices such as grayscale and sepia while keeping the existing general path for matrices with RGB offsets, alpha reads, or alpha changes.