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Re: [Public WebGL] Minefield brings system to halt



I raised a problem a few weeks ago where attrib 0 has to be bound to the vertex position. I got around this by simply ensuring that I always bind vertex position to attrib 0. Ken Russell/Vlad discussed this and I believe their intention was to ensure that ES2 behavior applied (which allows any attribute to be bound to 0). I haven't removed my patch, so I've no idea if this was resolved. If you search the list you should find the conversations.

HTH

Alan


On 9/21/2010 8:23 AM, Benoit Jacob 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 ... ;-)

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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