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

The simple solution for now, always ask for an RGBA backbuffer?

On Wed, Jun 8, 2011 at 1:20 AM, Mikko Mononen <mikko@tinkercad.com> wrote:


Thanks, I'll have a look at the dev channel.

Actually our issue seems to be pretty much exactly as described in
issue 82420: http://code.google.com/p/chromium/issues/detail?id=82420

Unfortunately many very important people seem to have these GPUs :( I
will try to see if I can find some way around the issue until the
drivers get fixed and will check dev channel too.


On Wed, Jun 8, 2011 at 10:57 AM, Vangelis Kokkevis <vangelis@google.com> wrote:
> On Wed, Jun 8, 2011 at 12:24 AM, Mikko Mononen <mikko@tinkercad.com> wrote:
>> Hi,
>> 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:
> https://bugs.webkit.org/show_bug.cgi?id=61091
> which should be available in the current 13.x+ (Dev channel and Canary)
> releases.  You might want to give it another try there.

Mikko Mononen, Software Engineer
http://tinkercad.com - Solid modeling for artists & makers

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