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Re: [Public WebGL] Volume Textures



Universally implementable?  This sounds like any shader I write should run on any implementation.  We all know this is not the case.  It is up to the developer to detect the limitations of the shader model on the device.  Which means writing a shader that runs on ps 3.0 and a lighter one that runs on ps 2.0, telling the user it won't run, etc., when we're talking about desktops.  With mobile devices the same applies, instruction count limitations vary.

How is this any different from detecting an extension at runtime, and using it if available?

I don't believe the "Universally implementable" argument is valid.  Otherwise, WebGL would only accept the most minimal vertex/fragment shaders.which would run on everything.

If we add the extension now, and later it gets added to the OES2.0 spec, we simply have "Webgl2" for instantiating the context which has volume textures added to the API and the extension removed.

WebGL is amazing, and I truly believe it is going to change the shape of everything internet.  We just need one last tweak for a very simple/clear/elegant well understood concept which has been around for quite a while.

JD

On Thu, Mar 24, 2011 at 9:42 PM, Benoit Jacob <bjacob@mozilla.com> wrote:



----- Original Message -----
> 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.

For what it's worth, I am agreeing with Chris on this matter.

To put it in more abstract terms: being a web specification, WebGL should (try hard to) be universally implementable.

Benoit
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