[Public WebGL] oes-texture-float conformance

Cedric Vivier [email protected]
Tue May 10 06:46:07 PDT 2011

On Tue, May 10, 2011 at 19:52, Benoit Jacob <[email protected]> wrote:
> The other concern about this test is the GC part. What is window.GCController? Is that a WebKit-ism? Do we really want to have browser-specific code in conformance tests? Other browsers will use attemptToForceGC() which may or may not actually result in a GC run, giving non-deterministic results. In short, I question whether it's a good idea for a conformance test to rely on GC runs.

I assume the intent is to test that the JavaScript object representing
a WebGLExtension cannot ever be collected while the owner
WebGLRenderingContext is alive, in order to provide singleton
semantics within the context lifetime.

Technically this means an extension object instance must have a GC
root to the WebGLRenderingContext object instance (ie.

> Section 5.13.14 says "Multiple calls to getExtension with the same extension string shall return the same object" but it's not entirely clear to me what that means in the case where the user modified that object in between, as we then have to choose between returning the modified object (behavior required by the test) or an object that is identical to the object that was returned the first time (which would be easy to implement).

Afaik the intent of the spec is that former.
These semantics makes sense as an extension object should work no
differently than other DOM JavaScript objects.

We should probably take the opportunity to clarify getExtension spec
using imperative style (getContext-style) :

getExtensions(name) method of the WebGLRenderingContext, when invoked,
must run the following steps:
1. Let name be the first argument to the method.
2. If extension name is not supported by this context, return null and
abort these steps.
3. If the getExtension method has already been invoked on this context
for the same extension name, return the same object as was returned
that time, and abort these steps.
4. Return a new extension object.


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