[Impeller] Make porter duff blended atlas calls faster. #44059
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| "filename": "flutter/impeller/entity/gles/porter_duff_blend.frag.gles", | ||
| "has_side_effects": false, | ||
| "has_uniform_computation": true, | ||
| "has_uniform_computation": false, |
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These moved to the vert.
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Golden file changes are available for triage from new commit, Click here to view. |
…gine into make_draw_vertices_fast
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Friendly ping 😄 |
chinmaygarde
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@bdero said he would take a look yesterday but he may be preoccupied. I took a stab instead and LGTM. If he has further comments, we can handle it in a later pass. Thanks!
| "filename": "flutter/impeller/entity/gles/porter_duff_blend.frag.gles", | ||
| "has_side_effects": false, | ||
| "has_uniform_computation": true, | ||
| "has_uniform_computation": false, |
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These moved to the vert.
bdero
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LGTM, but can we add a golden that uses AtlasContents?
Summary of my understanding:
- The
porter_duff_blendis reworked to distribute the tiles while performing the blend at the same time. - The blend shader needs to be reversed because the blended colors are actually the destination: https://api.flutter.dev/flutter/dart-ui/Canvas/drawAtlas.html
In an engine sync you mentioned that the blend isn't behaving correctly, but I wasn't able to spot a potential problem.
I might have mispoke, I didn't mean with this patch but at ToT. In general there is a problem with some of the blending with the current implementation. Those issues are linked in the above issue but in particular: flutter/flutter#118914 So I'm trying to move us closer to what Skia is doing without adding more shaders. |
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Oh! I notice that issue is from January. We discovered some tricky alpha management issues while comprehensively covering the blends with goldens & comparing with Skia -- maybe it's already fixed by #43283? BTW, if you're planning to employ a trick like this to make the advanced blends faster in DrawAtlas and/or DrawVertices, I think that would also be a great way to resolve the mask tracking issue I was worried about. Although in the case of DrawAtlas/DrawVertices, the issue is confined to edges looking a bit discolored rather than the whole blended square getting colored in for some blend modes. |
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Oh nice, that's right you fixed that. I'll need to recheck. |
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Are we landing this? |
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Waiting on benchmarks |
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Benchmarks have landed, will monitor and ensure those are running and then land later this week. |
flutter/engine@22f03ff...a9da721 2023-08-15 skia-flutter-autoroll@skia.org Roll Skia from c7c9e85a8657 to b07a6964a1cf (2 revisions) (flutter/engine#44733) 2023-08-15 jonahwilliams@google.com [Impeller] Make porter duff blended atlas calls faster. (flutter/engine#44059) 2023-08-15 skia-flutter-autoroll@skia.org Roll Skia from 4beb6fd05f4f to c7c9e85a8657 (7 revisions) (flutter/engine#44729) 2023-08-15 skia-flutter-autoroll@skia.org Roll Dart SDK from 19c87486f0a9 to b36934aae968 (1 revision) (flutter/engine#44728) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-engine-flutter-autoroll Please CC jsimmons@google.com,rmistry@google.com,zra@google.com on the revert to ensure that a human is aware of the problem. To file a bug in Flutter: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md
This implements part of flutter/flutter#131345 --- Makes all porter-duff draw atlas blending avoid subpass creation, by tweaking the existing porter duff shader to support per-vertex colors and output opacity. This requires a small trick: What the blend shaders and what (drawAtlas/drawVertices) consider the source and destination is reversed. That is a blend mode color filter treats the color as the source whereas drawVertices/drawAtlas treat their per-vertex colors as the destination. Therefore I cannot simply make all color inputs per vertex and use the exact same shaders :( However, for the porter duff blends we should just be able to reverse the blend mode (srcover -> dstOver, xor->xor) (I'm pretty sure I did this correctly) so that the blending is still correct. I don't think we can do this for the advanced blends, but supporting those is less important than the common atlas blending parameters like dstIn. This PR only updates drawAtlas.
This implements part of flutter/flutter#131345
Makes all porter-duff draw atlas blending avoid subpass creation, by tweaking the existing porter duff shader to support per-vertex colors and output opacity. This requires a small trick: What the blend shaders and what (drawAtlas/drawVertices) consider the source and destination is reversed. That is a blend mode color filter treats the color as the source whereas drawVertices/drawAtlas treat their per-vertex colors as the destination. Therefore I cannot simply make all color inputs per vertex and use the exact same shaders :(
However, for the porter duff blends we should just be able to reverse the blend mode (srcover -> dstOver, xor->xor) (I'm pretty sure I did this correctly) so that the blending is still correct. I don't think we can do this for the advanced blends, but supporting those is less important than the common atlas blending parameters like dstIn.
This PR only updates drawAtlas.