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Re: [Public WebGL] Volume Textures



>
>
> On Mar 24, 2011, at 4:18 AM, John Davis wrote:
>
>> In the meantime, is there any chance we could add an extension to WebGL
>> and Angle to support volume textures for the rather large use case of
>> Chrome and FireFox?  This is very low hanging fruit that will add
>> considerable bang on the fragment shader side.
>
> Let's be careful about what we call "low hanging fruit". WebGL attempts to
> allow content to be written across a wide range of hardware. That's why we
> based the spec on OpenGL ES 2.0 rather than desktop OpenGL. If you look at
> the WebGL extension registry
> (http://www.khronos.org/registry/webgl/extensions/), all of the extensions
> there are available on at least one OpenGL ES implementation on mobile
> devices (iPhone).
>
> That doesn't mean we can't discuss other extensions (like this one). But I
> would be very against adding any and all extensions just because they
> exist on some driver in some version of OpenGL on some platform. I even
> agree that 3D textures are available in a majority of desktop OpenGL
> implementations. And GL_OES_texture_3D is defined for OpenGL ES. But I
> don't know of any current implementations of OpenGL ES that support it.
>
> My concern is that WebGL will get fragmented and that authors will start
> using extensions that are available on a small number of implementations
> degrading the WebGL experience for everyone else. I don't think we want to
> go there at this early stage of development.

I agree - with a caveat.

It should be possible to support extensions for which a reasonable
fallback exists - so that people can develop applications that will at
least run (albeit a little slower - and perhaps a little less glitzy) on
every WebGL platform.

In cases like floating point textures - you can see how to work around the
absence of them (eg by packing your floats into three bytes and storing
them in R,G,B).   But it's rather hard to see how a reasonably simple
fallback would replace a 3D texture in the event of it not being present.

So while the floating point extension can provide enhanced quality on
hardware that supports it - a 3D texture extension would be an open
invitation to make applications that simply don't work (by design) on
lower end hardware.

That's a tougher sell, IMHO.

  -- Steve



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