Backends: Rework blending equation to preserve alpha in output buffer accross all backends. (#2693, #2764, #2766, #2873, #3447, #3813, #3816)

Some of the viewport ideas from #2766 are not in there yet (e.g. Vulkan: setting compositeAlpha based on cap.supportedCompositeAlpha)
This commit is contained in:
ocornut 2021-02-17 19:29:07 +01:00
commit bda12e5fdd
11 changed files with 31 additions and 14 deletions