All of the functions that create and destroy shaders are now wrapped
in the CoglGLES2Context so that we can track some extra data for them.
There are hash tables mapping object IDs to the corresponding data.
The data is currently not used for anything but will be in later
patches.
The glUseProgram, glAttachShader and glDetachShader functions
additionally need to be wrapped because GL does not delete shader
objects that are in use. Therefore we need to have a reference count
on the data so we can recognise when the last use has been removed.
The IDs are assumed to be specific to an individual CoglGLES2Context.
This is technically not the case because all of the CoglGLES2Contexts
are in the same share list. However we don't really want this to be
the case so currently we will assume sharing the object IDs between
contexts is undefined behaviour. Eventually we may want to actually
enforce this.
Reviewed-by: Robert Bragg <robert@linux.intel.com>
(cherry picked from commit 05dc1e34785ae5f5484cd398ecc5464bd8bd3dcd)
In GL, the default viewport and scissor should be set to the size of
the first surface that the context is bound to. If a CoglGLES2Context
is first used with an offscreen framebuffer then this surface will
actually be the dummy 1x1 window which will mess up the defaults. To
fix that, this patch makes it just always override the viewport and
scissor the first time the context is bound to something.
Reviewed-by: Robert Bragg <robert@linux.intel.com>
(cherry picked from commit 02567b3e6b64e6849b9f7c6aa2137401be7ece8d)
This makes it possible to integrate existing GLES2 code with
applications using Cogl as the rendering api.
Currently all GLES2 usage is handled with separate GLES2 contexts to
ensure that GLES2 api usage doesn't interfere with Cogl's own use of
OpenGL[ES]. The api has been designed though so we can provide tighter
integration later.
The api would allow us to support GLES2 virtualized on top of an
OpenGL/GLX driver as well as GLES2 virtualized on the core rendering api
of Cogl itself. Virtualizing the GLES2 support on Cogl will allow us to
take advantage of Cogl debugging facilities as well as let us optimize
the cost of allocating multiple GLES2 contexts and switching between
them which can both be very expensive with many drivers.
As as a side effect of this patch Cogl can also now be used as a
portable window system binding API for GLES2 as an alternative to EGL.
Parts of this patch are based on work done by Tomeu Vizoso
<tomeu.vizoso@collabora.com> who did the first iteration of adding GLES2
API support to Cogl so that WebGL support could be added to
webkit-clutter.
This patch adds a very minimal cogl-gles2-context example that shows how
to create a gles2 context, clear the screen to a random color and also
draw a triangle with the cogl api.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
(cherry picked from commit 4bb6eff3dbd50d8fef7d6bdbed55c5aaa70036a8)
