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Re: [Public WebGL] glGetUniform



----- "Kenneth Russell" <kbr@google.com> wrote:

> On Wed, May 19, 2010 at 10:51 AM, Benoit Jacob <bjacob@mozilla.com>
> wrote:
> > Hi List,
> >
> > Disclaimer : complete newbie here.
> >
> > I have a question about glGetUniform.
> >
> > From section 5.14.10 "Uniforms and attributes":
> >
> > any getUniform(WebGLProgram program, WebGLUniformLocation location)
> >
> > In order to implement this, we need to be able to determine the base
> type of that variable (int or float). How to do this? The only GL
> function that I see returning that info is glGetActiveUniform, but it
> wants an 'index' parameter, not a 'location' parameter.
> >
> > If this is not possible, should the spec be edited to have
> getUniformiv and getUniformfv functions like in OpenGL ES?
> 
> It's a two-step process. First you need to iterate all of the active
> uniforms for the current program. For each you then need to call
> glGetUniformLocation and see whether the location is equal to that
> passed in the WebGLUniformLocation object. See
> http://trac.webkit.org/browser/trunk/WebCore/html/canvas/WebGLRenderingContext.cpp#L1355
> . This can be made more efficient with caches but since OpenGL get
> calls aren't designed to be efficient it's a reasonable start.

Many thanks for the answer!

Benoit

> 
> -Ken
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