[macOS] Issues on nVidia hardware

[_mental_]

This commit introduced couple of issues on nVidia hardware.

Colors during wipe animations are broken, see this video. The type of wipe effect doesn't matter.
Reproduced on all Macs with nVidia graphics I tried.

The following screenshots were taken on ancient 9400M:

gzdoom_main_menu.jpg

gzdoom_ingame.jpg

gzdoom_console.jpg

This issue however doesn't happen on newer hardware like 650M or 750M.

Running GZDoom from Apple's OpenGL Profiler didn't reveal any errors.
Integrated Intel graphics seem to be no affected by this change and I cannot test on ATI/AMD.
Reverting the commit solves all problems.
I'm using the latest source code at the moment.

[dpJudas]

Very odd that the texture format should affect the blend mode.

I think you can safely revert that particular commit though. It was testing the possibility that the texture format could be causing the black screen problem, which turned out to have no effect there. Ideally we'd be using rgba16f over rgba16.

[_mental_]

I reverted the format back to RGBA16F as I cannot figure out why RGBA16 doesn't work correctly in this particular case.
The topic can be moved to Closed Bugs.

[Graf Zahl]

This sounds like a driver bug. It's rare that something like this happens on NVidia...