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Re: [Public WebGL] How to handle partially failing getContext()

On Wed, Jun 8, 2011 at 12:24 AM, Mikko Mononen <mikko@tinkercad.com> wrote:


I have been inspecting a bug in our app where Intel HD GPUs will just
render a black screen when using Chrome 12 in win7. Firefox seems to
blacklist this GPU.

The problem is triggered by calling getContext() with 'alpha' attrib
set to false (I want opaque composition). In that case the
getContext() returns a valid context and sets webgl error to "invalid
argument". Any rendering with that context will result a black
rectangle on screen. If I set alpha to true, I can see that the
rendering is correct, but the composition is of course different too.

There was an issue we had discovered with some AMD gpus on recent macs that had the same symptoms.  It looks like what was happening was that even though we were asking for an RGB only backbuffer (a texture attached to an fbo in our case), the driver was allocating an RGBA buffer and the alpha channel values (initialized to 0) would prevent the WebGL content from showing up.  This was addressed for chrome with a change in the compositor:


which should be available in the current 13.x+ (Dev channel and Canary) releases.  You might want to give it another try there.