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[Public WebGL] Bug in oes-texture-float conformance test



Mark Callow has pointed out yet another problem in WebGL's exposure of
the OES_texture_float extension:
http://www.khronos.org/registry/webgl/extensions/OES_texture_float/

The WebGL version of this extension supports optional rendering to
floating-point (FP) textures, even though this is strictly speaking
not allowed by OpenGL ES 2.0.

Further, to date, the WebGL conformance test for this extension has
required that FP render targets be supported, as a
quality-of-implementation issue. The expectation has basically been
that this extension would only be available on desktop platforms until
next-generation (OpenGL ES 3.0) hardware arrives.

Now there are some mobile vendors wishing to expose the
OES_texture_float extension in their WebGL implementations. They
support the underlying GL_OES_texture_float extension but not FP
render targets. See
http://www.khronos.org/bugzilla/show_bug.cgi?id=729 , which points out
quite rightly that the conformance test is testing something the spec
doesn't say.

Should we:

1) Change the conformance test to make FP render target support optional
2) Change the spec to require FP render target support

(1) might break some WebGL demos because they might be incorrectly
assuming that the OES_texture_float extension implies FP render target
support -- because the conformance test has enforced this to date.
(2) would prevent the majority of OpenGL ES 2.0 implementations from
exposing OES_texture_float support. I've been told that the extension
is useful even without FP render target support, though my opinion is
that it's much more useful when FP render targets are supported.

Thoughts please? Would like to resolve this issue soon.

Thanks,

-Ken

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