vello_gpu: Do not optimize away transparent draws - #1966
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Draws with a fully transparent solid paint were skipped before the inline filter layer was pushed or the draw was recorded into an enclosing filter layer. A filter can make that geometry visible (a flood fills it, a color matrix can add an alpha offset), so the draw disappeared on the GPU while vello_cpu, which never skips it, rendered it. Only skip transparent draws when no filter is active.
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Thanks! We've decided it's easier to simply not optimize away transparent draws. This was introduced in #998, but the original failure seems to have disappeared already. |
LaurenzV
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Oct 1, 2026
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vello_gpuskips draws whose solid paint is fully transparent, since they normally can't change the output. That doesn't hold under a filter: a flood fills the drawn geometry whatever its paint, and a color matrix with an alpha offset (#1765) can make transparent pixels visible. The skip happens before the inline filter layer is pushed or the draw is recorded into an enclosing filter layer, so on the GPU such a draw disappears, whilevello_cpu, which doesn't skip transparent draws, renders it.This keeps transparent draws while a filter is active, meaning an inline filter effect or any open filter layer. Outside of filters nothing changes.
The new
filter_flood_transparent_painttest floods a fully transparent rect, once in a filter layer and once with an inline filter effect. On main the CPU variants pass and the GPU variant renders nothing.Found in the review of #1765.
This PR was generated by Claude.