[Bug 59436] New: Wayland/EGL: Washed-out colors caused by double sRGB conversion on default framebuffer (GL_FRAMEBUFFER_SRGB)

[WineHQ Bugzilla]

http://bugs.winehq.org/show_bug.cgi?id=59436

            Bug ID: 59436
           Summary: Wayland/EGL: Washed-out colors caused by double sRGB
                    conversion on default framebuffer
                    (GL_FRAMEBUFFER_SRGB)
           Product: Wine
           Version: 11.3
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: winewayland
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

Created attachment 80417
  --> http://bugs.winehq.org/attachment.cgi?id=80417
Patch

Fixes https://bugs.winehq.org/show_bug.cgi?id=59073


Summary

When running Wine with the Wayland driver (winewayland.drv) using EGL, colors
may appear washed out / desaturated in OpenGL applications.
The issue is caused by GL_FRAMEBUFFER_SRGB remaining enabled while rendering to
the default framebuffer (FBO 0), leading to a double gamma/sRGB conversion in
some Wayland/EGL pipelines.

Disabling GL_FRAMEBUFFER_SRGB only when rendering to the default framebuffer
fixes the color output.


Environment

Wine: wine-git (tested on 11.x, reproducible on current master)

Backend: winewayland.drv (Wayland native, not XWayland)

GPU: AMD (Mesa)

Compositor: wlroots-based (qtile Wayland)

EGL backend in use

Application tested: Roon (Chromium/CEF-based UI, OpenGL rendering)

Observed behavior

Colors appear faded / washed out

Gamma looks incorrect (as if double sRGB conversion occurs)

Issue only occurs under Wayland/EGL

Colors are correct:

Under X11/XWayland

Or if GL_FRAMEBUFFER_SRGB is manually disabled for FBO 0


Root cause hypothesis

Some Wayland/EGL compositors already perform colorspace handling for the window
surface.
If GL_FRAMEBUFFER_SRGB remains enabled when rendering to the default
framebuffer, the pipeline applies sRGB conversion twice:

App → GL_FRAMEBUFFER_SRGB → EGL/Compositor colorspace → Display

This results in desaturated output.

Minimal fix

Disable GL_FRAMEBUFFER_SRGB only when binding the default framebuffer (FBO 0),
while preserving the application's requested sRGB state for non-default FBOs.


Example patch (conceptual)

Inside framebuffer binding path:

if (!framebuffer && gl_info->supported[ARB_FRAMEBUFFER_SRGB])
{
    TRACE("glBindFramebuffer disabling GL_FRAMEBUFFER_SRGB on default
framebuffer\n");
    glDisable(GL_FRAMEBUFFER_SRGB);
}
else if (framebuffer && app_framebuffer_srgb_enabled)
{
    TRACE("glBindFramebuffer restoring GL_FRAMEBUFFER_SRGB on non-default
framebuffer\n");
    glEnable(GL_FRAMEBUFFER_SRGB);
}


Results

Colors become correct under Wayland/EGL

No regression observed in tested OpenGL apps

Behavior matches X11 output

sRGB still works correctly for offscreen FBO rendering

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