Wayland: Fix window opacity on older systems

On systems lacking the EGL_EXT_present_opaque extension, some
compositors treat any buffer with an alpha channel as per-pixel
transparent.

This commit ignores any EGLConfig with an alpha channel if the extension
is missing and the window is created with GLFW_TRANSPARENT_FRAMEBUFFER
set to false.

This is technically not a breaking change since GLFW_ALPHA_BITS is not
a hard constraint, but it is still going to inconvenience anyone using
the framebuffer alpa channel to store other kinds of data.

Related to #1895

(cherry picked from commit ef6c9d8b4f)
This commit is contained in:
Camilla Löwy 2022-07-25 20:33:47 +02:00
parent 1f675ab62f
commit 8b4f1ebbea
4 changed files with 28 additions and 0 deletions

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@ -180,6 +180,7 @@ video tutorials.
- pthom - pthom
- Martin Pulec - Martin Pulec
- Guillaume Racicot - Guillaume Racicot
- Christian Rauch
- Philip Rideout - Philip Rideout
- Eddie Ringle - Eddie Ringle
- Max Risuhin - Max Risuhin

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@ -124,6 +124,8 @@ information on what to include when reporting a bug.
## Changelog ## Changelog
- [Wayland] Bugfix: Connecting a mouse after `glfwInit` would segfault (#1450) - [Wayland] Bugfix: Connecting a mouse after `glfwInit` would segfault (#1450)
- [Wayland] Disabled alpha channel for opaque windows on systems lacking
`EGL_EXT_present_opaque` (#1895)
- [Linux] Bugfix: Joysticks without buttons were ignored (#2042,#2043) - [Linux] Bugfix: Joysticks without buttons were ignored (#2042,#2043)
[EGL] Added loading of glvnd `libOpenGL.so.0` where available for OpenGL [EGL] Added loading of glvnd `libOpenGL.so.0` where available for OpenGL
- [GLX] Added loading of glvnd `libGLX.so.0` where available - [GLX] Added loading of glvnd `libGLX.so.0` where available

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@ -312,6 +312,19 @@ Starting with GLFW 3.3.7, events posted with @ref glfwPostEmptyEvent now use a s
unnamed pipe instead of sending an X11 client event to the helper window. unnamed pipe instead of sending an X11 client event to the helper window.
@subsubsection wayland_alpha_34 Frambuffer may lack alpha channel on older Wayland systems
On Wayland, when creating an EGL context on a machine lacking the new
`EGL_EXT_present_opaque` extension, the @ref GLFW_ALPHA_BITS window hint will be
ignored and the framebuffer will have no alpha channel. This is because some
Wayland compositors treat any buffer with an alpha channel as per-pixel
transparent.
If you want a per-pixel transparent window, see the
[GLFW_TRANSPARENT_FRAMEBUFFER](@ref GLFW_TRANSPARENT_FRAMEBUFFER_hint) window
hint.
@subsection deprecations_33 Deprecations in version 3.3 @subsection deprecations_33 Deprecations in version 3.3
@subsubsection charmods_callback_33 Character with modifiers callback @subsubsection charmods_callback_33 Character with modifiers callback

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@ -172,6 +172,18 @@ static GLFWbool chooseEGLConfig(const _GLFWctxconfig* ctxconfig,
u->depthBits = getEGLConfigAttrib(n, EGL_DEPTH_SIZE); u->depthBits = getEGLConfigAttrib(n, EGL_DEPTH_SIZE);
u->stencilBits = getEGLConfigAttrib(n, EGL_STENCIL_SIZE); u->stencilBits = getEGLConfigAttrib(n, EGL_STENCIL_SIZE);
#if defined(_GLFW_WAYLAND)
// NOTE: The wl_surface opaque region is no guarantee that its buffer
// is presented as opaque, if it also has an alpha channel
// HACK: If EGL_EXT_present_opaque is unavailable, ignore any config
// with an alpha channel to ensure the buffer is opaque
if (!_glfw.egl.EXT_present_opaque)
{
if (!desired->transparent && u->alphaBits > 0)
continue;
}
#endif // _GLFW_WAYLAND
u->samples = getEGLConfigAttrib(n, EGL_SAMPLES); u->samples = getEGLConfigAttrib(n, EGL_SAMPLES);
u->doublebuffer = desired->doublebuffer; u->doublebuffer = desired->doublebuffer;