Commit 1026327c authored by Committed by Eric Anholt
Add the feature of generating linear gradient picture by using shader.
Add the feature of generating linear gradient picture by using shader. This logic will replace the original linear gradient picture generating manner in glamor which firstly use pixman and then upload it to GPU. Compare it to the result generated by pixman, the difference of each color component of each pixel is normally 0, sometimes 1/255, and 2/255 at most. The pixman use fixed-point but shader use float-point, so may have difference. The feature of transform matrix and 4 types of repeat modes have been supported. The array usage in shader seems slow, so use 8 uniform variables to avoid using array when stops number is not very big. This make code look verbose but the performance improved a lot. We still have slightly performance regression compare to original pixman version. There are one further optimization opportunity which is to merge the gradient pixmap generation and the latter compositing into one shader, then we don't need to generate the extra texture, we can use the gradient value directly at the compositing shader. Hope that can beat pixman version. Will do that latter. Reviewed-by: Chris Wilson <firstname.lastname@example.org> Reviewed-by: Zhigang Gong <email@example.com> Signed-off-by: Zhigang Gong <firstname.lastname@example.org>
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