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Re: [Public WebGL] Minefield brings system to halt



On Tue, Sep 21, 2010 at 8:23 AM, Benoit Jacob <bjacob@mozilla.com> wrote:
> ----- Original Message -----
>> Hi Benoit,
>>
>> thank you for your fast response.
>>
>> Am 21.09.2010 16:30, schrieb Benoit Jacob:
>> > Another thing that's worth trying is setting webgl.shader_validator
>> > to false, to see if it's an issue with our ANGLE copy or the way
>> > that we're using it.
>>
>> I first started testing in Firefox Beta: when disabling the shader
>> validator both mentioned demos (the shadows and the cube map/
>> multi-texture shader) both work again as expected :-) (though the
>> console still tells s.th. about "been bound to a different target").
>>
>> This really hints to an ANGLE problem, because I then double checked
>> my
>> Chromium settings and remembered that there I have had to activate the
>> "--use-gl=desktop" flag to make it work (Chrome Beta is ok without)...
>
> Ah! Very interesting.
>
> I would like to report to ANGLE but this is quite nontrivial as we would probably need a small testcase. If we could bisect it to a precise shader, that would probably help!
>
> Alternatively, there's a good hope that some ANGLE devs are reading this list anyway ... ;-)

In Chromium top of tree on Windows Vista 64 with NVIDIA hardware and
running on top of ANGLE (r429),
http://www.x3dom.org/x3dom/example/x3dom_composedShader.xhtml renders
correctly, but http://x3dom.org/x3dom/example/x3dom_shadows.xhtml
shows up with all black geometry. There is definitely a bug somewhere
because with --use-gl=desktop the shadows example renders. At minimum
the behavior should be identical, though I can't say without a smaller
test case which behavior is correct.

-Ken

>> Concerning NeedFakeVertexAttrib0() I'd assume that this check is
>> simply
>> too vague,
>
> Well the check that results in the error message is in the part of the code that I elided. There are still questions that could not be easily explained by a bug there:
>  - why does the VBO have no data when drawElements is called? Is it a race condition in loading resources, as was suspected last week on this list about the Caves demo?
>  - why does drawElements get called to draw only 1 vertex?
>
> Cheers,
> Benoit
>
>> since there hasn't been any problem with rendering before,
>> at
>> least on those machines with a fairly good GPU -- even in the case
>> attribute 0 wasn't set (what I admittedly don't know because I haven't
>> checked it as we dynamically assign the locations based on the name of
>> the respective attribute in the shader via getAttribLocation).
>>
>> Cheers
>> Yvonne
>>
>>
>> --
>> Yvonne Jung
>> Fraunhofer-IGD | Tel.: ++49-6151-155-290
>> Fraunhoferstr. 5 | Fax.: ++49-6151-155-196
>> 64283 Darmstadt | email: yvonne.jung@igd.fraunhofer.de
>> Germany | http://www.igd.fhg.de/igd-a4
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