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Fix alpha blending in WebGL backends #650

Merged
merged 10 commits into from
Aug 25, 2021
Merged

Fix alpha blending in WebGL backends #650

merged 10 commits into from
Aug 25, 2021

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AsmPrgmC3
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This fixes alpha blending in the WebGL backends by first blending everything in a linear framebuffer, before converting the result to sRGB in a second shader.

The results of the color test are now identical to the egui_glium backend when using the WebGL2 backend.
The WebGL1 backend suffers from reduced precision in dark colors without the SRGB8_ALPHA8 format and still doesn't have correct texture interpolation.

Color test with the change (I have since removed the warning):
WebGL2
WebGL2
WebGL1
WebGL1

(Sorry for not following the contributing guidelines exactly ("First file an issue" and all that). This was a spontaneous test as I didn't know whether it was even possible and I didn't wan't to file an issue the same minute as closing it (Should I?).)

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@emilk emilk left a comment

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This is wonderful work; thank you so much!

As I noted in my review I think the WebGL1 pipeline should remain as it was, but the improvements to the WebGL2 renderer is massive, and works great! ❤️

egui_web/src/shader/main_fragment_100es.glsl Outdated Show resolved Hide resolved
egui_web/src/webgl1.rs Outdated Show resolved Hide resolved
egui_demo_lib/src/apps/color_test.rs Show resolved Hide resolved
epaint/src/texture_atlas.rs Outdated Show resolved Hide resolved
AsmPrgmC3 and others added 2 commits August 25, 2021 18:26
Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
@emilk emilk merged commit 31a1882 into emilk:master Aug 25, 2021
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emilk commented Aug 25, 2021

Thank you again!

mankinskin pushed a commit to mankinskin/egui that referenced this pull request Sep 29, 2021
Add a render-to-texture step with an sRGBA8 texture
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2 participants