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Re: [Public WebGL] WebGL

On Fri, Nov 18, 2011 at 10:42 AM, Chris Marrin <cmarrin@apple.com> wrote:
> On Nov 17, 2011, at 2:05 PM, Kenneth Russell wrote:
>> ...
>> OES_texture_npot doesn't appear to be widely supported. On iOS, http://developer.apple.com/library/ios/#documentation/3DDrawing/Conceptual/OpenGLES_ProgrammingGuide/OpenGLESPlatforms/OpenGLESPlatforms.html indicates that the supported variant is APPLE_texture_2D_limited_npot, which has restrictions. A little less than 50% of the devices listed on http://stackoverflow.com/questions/3881197/opengl-es-2-0-extensions-on-android-devices support OES_texture_npot. Some of the devices support GL_IMG_texture_npot, but I can't find a definition for that extension.
>> The best path forward might be to define a WebGL extension which covers the least common denominator of all of these extensions, so that it can be supported on the majority of existing hardware.
> APPLE_texture_2D_limited_npot is not relevant to this discussion. These features are already part of the OpenGL ES 2.0 standard. The limitations are listed in section 3.8.2 of the spec.

OK, I thought that APPLE_texture_2D_limited_npot relaxed some of the
OpenGL ES 2.0 restrictions as well, but was wrong.

IMG_texture_npot seems to be a more restricted subset of
OES_texture_npot, but there doesn't seem to be public documentation
about it.

Therefore it looks like a minority of mobile hardware supports
OES_texture_npot today.

I think that adding an OES_texture_npot WebGL extension at this point
is likely to fragment the WebGL ecosystem. It isn't like it's
impossible to do texturing in WebGL without it; the developer just has
to pay more attention to the creation of assets, or render different
geometry to achieve tiling. The benefit in doing so is that the
content will run on all mobile devices once they support WebGL. Since
we are still struggling to get the first WebGL implementations on
mobile devices, it seems likely that content will be developed that
only works with OES_texture_npot, and this essentially means desktop
devices. I recommend to work within the limitations of the current
spec for the time being.


> What OES_texture_npot does is to remove the restrictions, primarily the mip-mapping and texture repeat. I don't know of any mobile hardware that supports any more than what is currently in OpenGL ES 2.0.
> -----
> ~Chris
> cmarrin@apple.com

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