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Re: [Public WebGL] Minefield brings system to halt



Am 21.09.2010 17:39, schrieb Alan Chaney:
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.

I vaguely remember, but I just checked this, and the vertex position is bound to 0. However, when iterating over all active attributes in JS, the order in which they appear does not always correspond with the number resulting from getAttribLocation().


Bye
Yvonne


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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--
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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