[Impeller] Switch to uniform arrays for gradient data #56294
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| float tile_mode; | ||
| vec4 decal_border_color; | ||
| float alpha; | ||
| int colors_length; |
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GLES 2.0 requires that we use a float for this 😨
| highp vec2 start_to_end; | ||
| float alpha; | ||
| float tile_mode; | ||
| int colors_length; |
| float tile_mode; | ||
| vec4 decal_border_color; | ||
| float alpha; | ||
| int colors_length; |
| @@ -53,6 +53,10 @@ class LinearGradientContents final : public ColorSourceContents { | |||
| const Entity& entity, | |||
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Can we also remove RenderTexture in this patch?
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Eventually, I want to leave the old stuff around while I get the new stuff working and then I can run comparisons for testing/benchmarking.
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Per other discussions I think we decided it would stay in case we get more than 256 colors. Eventually we hope to have a vertex tiling solution that works efficiently on all platforms, but until then we'll still have the issue with zero-length stops on older platforms, but only if there are more than 256 stops total...
| /** | ||
| * @brief Populate 2 arrays with the colors and stop data for a gradient | ||
| * | ||
| * The color data is simple converted to a vec4 format, but the stop data |
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FYI - The latest push uses the Uniform versions of the shaders for all types as long as there are fewer than 256 colors. References to the old shaders are commented out for now just as a test run to test the new shaders as much as possible. If the test results are fine then I'll restore and finalize the code. |
| @@ -145,4 +145,30 @@ vec3 IPComputeFixedGradientValues(float t, float colors_length) { | |||
| return vec3(lower_index, upper_index, scale); | |||
| } | |||
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| vec4 IPComputeColorFromTables(vec4 colors[256], | |||
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I don't think this is used any more as the call overhead swamped everything else. I'll delete when I finalize the code.
Currently the most generalized form of the Impeller gradient shaders uses an SSBO to store the gradient information, but SSBO data is not supported on older platforms. To make the capability more general we introduce variants of the gradient shaders that uses uniform arrays which are more widely supported.
[Currently in draft form - the new shaders are written and example entity content code is written to demonstrate the approach for early reviews, but it is not yet plumbed into the system]