[Impeller] Implement Color blend mode #36120
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impeller/entity/entity.cc
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| std::min(value.z, threshold), std::min(value.w, threshold)); | ||
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| Color blendColor(const Color& src, |
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Not an expert about rendering here, but I wonder whether this is efficient or not? Seems that the cost of a switch has to be performed for each and every color.
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I wouldn't worry about the performance until we have traces that show performance here is a bottleneck. That said, if we did need to change things, we could always up this function to operate over an entire vector at once.
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I wouldn't worry about the performance until we have traces that show performance here is a bottleneck.
You are right!
we could always up this function to operate over an entire vector at once
That is what I was thinking :)
| auto sample_rect = texture_coords_[i]; | ||
| auto matrix = transforms_[i]; | ||
| auto color = (colors_.size() > 0 ? colors_[i] : Color::Black()); | ||
| auto color = (colors_.size() > 0 |
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I don't believe that this is correct - for drawAtlas we blend the colors with the texture sample which must be done in the shader: https://api.flutter.dev/flutter/dart-ui/Canvas/drawAtlas.html
Blend each rectangular portion of the image specified by an entry in the rects argument with its associated entry in the colors list using the blendMode argument (if a color is specified). In this part of the operation, the image part will be considered the source of the operation and the associated color will be considered the destination.
bdero
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Looking good so far -- mostly comments about where stuff should live.
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impeller/entity/entity_unittests.cc
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| auto generator_expected_colors = [](Color& src, |
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I would not use a closure like this to generate the expected colors. A frequent mistake made with this sorts of tests, is that someone writes some code (with a bug), copies and pastes the implementation into the test generator (with the same bug) and asserts that they are the same - which they will be, but still wrong.
Instead each test case should have a specified color that a developer could easily cross reference with an external source
bdero
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LGTM after addressing final comments, thanks!
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* Add color blend mode * Move Entrity::BlendMode to Color file; Add unittest for blendMode color * Fix some comments * fix comments * delete the redundancy code
Implement blend param in DrawVertices and DrawAtlas
Association issue: flutter/flutter#108047