With QtQuick2 it's possible that the scene graph rendering context either
lives in an own thread or uses the main GUI thread. In the latter case
it's the same thread as our compositing OpenGL context lives in. This
means our basic assumption that between two rendering passes the context
stays current does not hold.
The code already ensured that before we start a rendering pass the
context is made current, but there are many more possible cases. If we
use OpenGL in areas not triggered by the rendering loop but in response
to other events the context needs to be made current. This includes the
loading and unloading of effects (some effects use OpenGL in the static
effect check, in the ctor and dtor), background loading of texture data,
lazy loading after first usage invoked by shortcut, etc. etc.
To properly handle these cases new methods are added to EffectsHandler
to make the compositing OpenGL context current. These calls delegate down
into the scene. On non-OpenGL scenes they are noop, but on OpenGL they go
into the backend and make the context current. In addition they ensure
that Qt doesn't think that it's QOpenGLContext is current by calling
doneCurrent() on the QOpenGLContext::currentContext(). This unfortunately
causes an additional call to makeCurrent with a null context, but there
is no other way to tell Qt - it doesn't notice when a different context
is made current with low level API calls. In the multi-threaded
architecture this doesn't matter as ::currentContext() returns null.
A short evaluation showed that a transition to QOpenGLContext doesn't
seem feasible. Qt only supports either GLX or EGL while KWin supports
both and when entering the transition phase for Wayland, it would become
extremely tricky if our native platform is X11, but we want a Wayland
EGL context. A future solution might be to have a "KWin-QPA plugin" which
uses either xcb or Wayland and hides everything from Qt.
The API documentation is extended to describe when the effects-framework
ensures that an OpenGL context is current. The effects are changed to
make the context current in cases where it's not guaranteed. This has
been done by looking for creation or deletion of GLTextures and Shaders.
If there are other OpenGL usages outside the rendering loop, ctor/dtor
this needs to be changed, too.
The main purpose of the opengl testapp was to set the environment
variable LIBGL_ALWAYS_INDIRECT if direct rendering is not supported
before glx gets initialized.
With Qt5 we may no longer set this environment variable. QtQuick
requires direct rendering. On IvyBridge QtQuick is crashing if the
variable is set. Thus we are no longer allowed to set it and thus the
complete test becomes pointless.
The test app basically whitelisted most drivers anyway, the only
drivers which were problematic are the proprietary Catalyst drivers.
It that's still a problem we can also disable OpenGL compositing on
those drivers through the recommendation in the GLPlatform.
This also means that the KWIN_DIRECT_GL variable is no longer useful.
With QtQuick2 KWin is no longer the only one having an OpenGL context
thus we need to ensure that our context is current. If not it results in
highly interesting crashes when our code is executed on the QtQuick
context.
The context is made current before we swap and before we start to render
a frame. During rendering a frame it's not made current again based on
the assumption that while we render there is no interference. If this
assumption doesn't hold, we need a more sophisticated solution at the
moment it seems to fix the crashes.
repaints caused by effects so far polluted the timing calculations
since they started the timer on the old vsync offset
This (together with undercut timing) lead to multiple frames in
the buffer queue, and ultimately to a blocking swap
For unsynced painting, it simply caused wrong timings - leading to
"well, kinda around 60Hz - could be 75 as just well".
REVIEW: 112368
CCBUG: 322060
that part is fixed in 4.11.2
This flag seems to be ignored by several OpenGL implementations,
so don't set it for now. Mesa may also stop accepting this flag
until forward-compatible contexts are fully supported.
enforce to "e" (cheap) when driver is still unknown after
detection must be assumed to have run, so a sane value is available
when the context is up
BUG: 322355
FIXED-IN: 4.11
REVIEW: 111548
* "" needs to be wrapped in QStringLiteral
* QString::fromUtf8 needed for const char* and QByteArray
* QByteArray::constData() needed to get to the const char*
the only thing it does on these systems is cause users
trouble because usually when there's a client where
unredirection makes sense, that uses OpenGL - and then
things break in the driver.
CCBUG: 252817
REVIEW: 111476
This method returns a matrix that transforms normalized or un-normalized
texture coordinates, taking the texture target and y-inversion flag into
account.
Remove support for OpenGL compositing without using a composite
overlay window. With this change kwin now also requires a
double-buffered framebuffer configuration.
glXCreateNewContext() is supposed to return NULL on failure, so let's
assume that it does. Don't try to create an indirect context when
creating a direct context failed. glXCreateNewContext() should return
an indirect context when a direct context cannot be created.
Use glXChooseFBConfig() instead of glXGetFBConfigs(), and prefer
the first usable configuration instead of the last.
Also rename initBufferConfigs() to initFbConfig().
either by
- forcing fullrepaints unconditionally
- turning a repaint to a full one beyond a threshhold
- completing the the backbuffer from the frontbuffer after the paint
BUG: 307965
FIXED-IN: 4.10
REVIEW: 107198
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.
