[Cogl] failure using cogl-gles2

[Robert Bragg]

Hi Mahesh,

My guess is that your platform doesn't have a native gles 2.0 library available.

Although Cogl supports running against different GL drivers (GLES
1.1/2.0 and GL 1.x/2.x/3.x) Cogl currently only supports
CoglGLES2Context integration (required by webkit-clutter) when running
on a native gles 2.0 driver and would give the error you're seeing if
you tried to create a CoglGLES2Context while running with a full GL
driver.

If your platform does have a native gles 2.0 driver then maybe your
Cogl library just needs to be rebuilt with --enable-gles2.

The plan at some point is that we will support the CoglGLES2Context
integration even when the native driver is a full GL driver but to do
that we will need to play tricks with the gles 2.0 GLSL shaders to
enable them to run with a full GL driver.

Note if the workaround to set COGL_DRIVER=gles2 does work for you then
that should probably be considered a bug in webkit-clutter I think
because Cogl does have api to let an application explicitly override
the driver. In the case of webkit-clutter since the CoglGLES2Context
api is currently documented to only work with the gles2 driver then
webkit-clutter should probably be trying to explicitly create a
context with a native gles2 driver.

I hope that helps a bit.

kind regards,
- Robert

On Wed, Jan 30, 2013 at 1:45 PM, mahesh gawali <maheshgawali at gmail.com> wrote:
> Hi All,
>
> I am trying to compile the webkit-clutter port v1.11 on x86. When I run
> webgl samples on it, I am getting the following error:
>
> Couldn't push GLES2 context: Failed to create an OpenGL framebuffer object
>
> this error is related to COGL in file cogl-framebuffer.c inside function
> try_creating_fbo()
>
> initially i used to get this error, but resolved it by doing export
> COGL_DRIVER=gles2
> ERROR **: Couldn't create GLES2 context: Backend doesn't support creating
> GLES2 contexts
>
> I have tried running the same webgl sample on chrome and it runs
> fine(http://learningwebgl.com/lessons/lesson01/index.html)
>
> I have put my backtrace here (http://pastebin.com/YVgVXBAe)
>
> Please let me know if anyone knows how to resolve this issue.
>
>
> P.S: webkit-clutter supports webgl as per
> http://blog.tomeuvizoso.net/2011/12/webgl-support-in-webkit-clutter.html
> using cogl-experimental backend
>
>
>
> - Mahesh
>
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