OpenGL is properly working if there is a direct rendering context.
If LIBGL_ALWAYS_INDIRECT is set VirtualBox falls back to Mesa's software
rasterizer. So in order to get OpenGL the driver is now whitelisted in
the opengltest.
GLPlatform is extended to recognize the VirtualBox driver and has new
methods to report whether it is a virtual machine and VirtualBox. The
detection is rather limited as we don't get access to the underlying
hardware, so we do not know whether the features are really supported.
We need to trust the driver here in announcing the right extensions.
The driver does not provide glxQueryDrawable although it is part of
GLX 1.3. A hack is added in the glxbackend to set the function pointer to
NULL. This can unfortunately not be done in glxResolveFunctions() as
QueryDrawable seems not to be provided by an extension (at least not
listed in the OpenGL registry) and getProcAddress resolves a function but
it only prints an OpenGL Warning to stderr.
As a note: the driver reports that it is using XSHM for
GLX_EXT_texture_from_pixmap.
REVIEW: 106821
According to the OpenGL ABI for Linux GLX 1.3 is a minimum requirement.
Therefore we do not need to resolve the symbols which are present in that
version.
KWin did always require at least 1.3, for all the resolved functions
there were checks in the Scene, but they might have been incorrect.
Instead now the GLX version is checked and OpenGL compositing is blocked
if there is not at least GLX 1.3.
REVIEW: 106704
The Egl backend is decoupled from the OpenGL ES build option which makes
it possible to use it as a replacement for glx.
To make this possible a new build flag is added when egl is available at
compile time and any egl specific code is now ifdefed with this flag
instead of the gles flag. In addition at runtime a windowing system enum
value is passed to the various detect methods to have egl/glx specific
detection for e.g. function pointer resolving.
By default egl is used if compiled with OpenGL ES, otherwise glx is used.
But in the non-gles case the windowing system can be selected through the
new environment variable KWIN_OPENGL_INTERFACE. Setting this variable to
"egl" the EglOnXBackend is used.
REVIEW: 106632
The handling for creating and managing the OpenGL context is
split out of the SceneOpenGL into the abstract OpenGLBackend
and it's two subclasses GlxBackend and EglOnXBackend.
The backends take care of creating the OpenGL context on the
windowing system, e.g. on glx an OpenGL context on the overlay
window is created and in the egl case an EGL context is created.
This means that the SceneOpenGL itself does not have to care
about the specific underlying infrastructure.
Furthermore the backend provides the Textures for the specific
texture from pixmap operations. For that in each of the backend
files an additional subclass of the TexturePrivate is defined.
These subclasses hold the EglImage and GLXPixmap respectively.
The backend is able to create such a private texture and for
that the ctor of the Texture is changed to take the backend as
a parameter and the Scene provides a factory method for
creating Textures. To make this work inside Window the Textures
are now hold as pointers which seems a better choice anyway as
to the member functions pointers are passed.
