When choosing an X11 Visual for a window based on its GLX capabilities, first
try glXChooseFBConfig (if available) before falling back to glXChooseVisual.
This normally does not make a difference because most GLX drivers create a
Visual for every GLXFBConfig, exposing all of the same capabilities.
For GLX render offload configurations (also know as "PRIME") where one GPU is
providing GLX rendering support for windows on an X screen running on a
different GPU, the GPU doing the offloading needs to use the Visuals that were
created by the host GPU's driver rather than being able to add its own. This
means that there may be fewer Visuals available for all of the GLXFBConfigs the
guest driver wants to expose. In order to handle that situation, the NVIDIA GLX
driver creates many GLXFBConfigs that map to the same Visual when running in a
render offload configuration.
This can result in a glXChooseVisual request failing to find a supported Visual
when there is a GLXFBConfig for that configuration that would have worked. For
example, when the game "Unnamed SDVX Clone" [1] tries to create a configuration
with multisample, glXChooseVisual fails because the Visual assigned to the
multisample GLXFBConfigs is shared with the GLXFBConfigs without multisample.
Avoid this problem by using glXChooseFBConfig, when available, to find a
GLXFBConfig with the requested capabilities and then using
glXGetVisualFromFBConfig to find the corresponding X11 Visual. This allows the
game to run, although it doesn't make me any better at actually playing it...
Signed-off-by: Aaron Plattner <aplattner@nvidia.com>
Fixes: https://forums.developer.nvidia.com/t/prime-run-cannot-create-window-x-glxcreatecontext/180214
[1] https://github.com/Drewol/unnamed-sdvx-clone
This patch was originally written by Marc Di Luzio for glX and enhanced by
Maximilian Malek for WGL, etc. Thanks to both of you!
Fixes Bugzilla #3643.
Fixes Bugzilla #3735.
Mark Callow
The attached patch does the following for the X11 and Windows platforms, the only ones where SDL attempts to use context_create_es_profile:
- Adds SDL_HINT_OPENGL_ES_DRIVER by which the application can
say to use the OpenGL ES driver & EGL rather than the Open GL
driver. (For bug #2570)
- Adds code to {WIN,X11}_GL_InitExtensions to determine the maximum
OpenGL ES version supported by the OpenGL driver (for bug #3145)
- Modifies the test that determines whether to use the OpenGL
driver or the real OpenGL ES driver to take into account the
hint, the requested and supported ES version and whether ES 1.X
is being requested. (For bug #2570 & bug #3145)
- Enables the testgles2 test for __WINDOWS__ and __LINUX__ and adds
the test to the VisualC projects.
With the fix in place I have run testdraw2, testgl and testgles2 without any issues and have run my own apps that use OpenGL, OpenGL ES 3 and OpenGL ES 1.1.
The internal function SDL_EGL_LoadLibrary() did not delete and remove a mostly
uninitialized data structure if loading the library first failed. A later try to
use EGL then skipped initialization and assumed it was previously successful
because the data structure now already existed. This led to at least one crash
in the internal function SDL_EGL_ChooseConfig() because a NULL pointer was
dereferenced to make a call to eglBindAPI().
