OpenGL apparently needs to not do any drawing between wl_egl_window_resize
and eglSwapBuffers, but Vulkan apps don't use SDL to present, so they
never call into an equivalent of SDL_GL_SwapWindow where our Wayland code
was handling pending resize work.
Fixes Bugzilla #4722.
For starters, we need to correctly respond to 0,0 configure after unsetting
fullscreen. Also, turns out that there should be no drawing calls at all
in between eglSwapBuffers and wl_egl_window_resize, as otherwise EGL can
already allocate a wrongly sized buffer for a next frame, so handle those
together.
Manuel
The attached patch adds support for KMS/DRM context graphics.
It builds with no problem on X86_64 GNU/Linux systems, provided the needed libraries are present, and on ARM GNU/Linux systems that have KMS/DRM support and a GLES2 implementation.
Tested on Raspberry Pi: KMS/DRM is what the Raspberry Pi will use as default in the near future, once the propietary DispmanX API by Broadcom is overtaken by open graphics stack, it's possible to boot current Raspbian system in KMS mode by adding "dtoverlay=vc4-kms-v3d" to config.txt on Raspbian's boot partition.
X86 systems use KMS right away in every current GNU/Linux system.
Simple build instructions:
$./autogen.sh
$./configure --enable-video-kmsdrm
$make
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().
