libretro / libretro/RetroArch

Red/Blue colours swap when disabling Double Buffering in SDL Driver

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Dominant language
C
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Description

Description

When I disable Double Buffering in the SDL driver (by removing HW_DOUBLEBUF from SDL_SetVideoMode), the menu is fine but in-game colours on all cores are messed up. Seems like the Red and Blue channels get swapped over. I made this change to stop screen flickering on the platform I'm using, but it created this problem!

Expected behavior

No change to in-game colours.

Actual behavior

Reds become Blues and Blues become Reds.

Steps to reproduce the bug

I change SDL_SetVideoMode to this -

vid->screen = SDL_SetVideoMode(video->width, video->height, 32,
SDL_SWSURFACE | (video->fullscreen ? SDL_FULLSCREEN : 0));

Bisect Results

[Try to bisect and tell us when this started happening]

Version/Commit

You can find this information under Information/System Information

  • RetroArch: [version/commit]
Environment information
  • OS: [The operating system you're running]
  • Compiler: [In case you are running local builds]

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Locate the SDL_SetVideoMode call in the SDL driver and compare the video surface format with the rendering path when HW_DOUBLEBUF is absent. Reproduce the reported configuration and verify that disabling double buffering leaves red and blue channels unchanged in-game.

Written by the indexing model from the issue text.

Assessment

Tech stack
c
Domain
frontend
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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