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Re: [Public WebGL] Volume Textures



Just for reference, the volume rendering demo that we posted last week, was also successfully tested on two Android mobile devices: a Samsung Galaxy S phone, and a Samsung Galaxy Tab. It was obviously slow, but it worked.

There is an additional problem we are facing with this kind of complex shader systems related with Angle in Windows. Angle is a great library that expands the potential audience of WebGL a lot. But going from GLSL to HLSL, some things can be "lost in translation".

That demo is set to a moderate complexity (iteration counts, etc.) and still takes several seconds to compile in Angle (more than via pure OpenGL). We have more complex systems that just fail to compile after minutes of trying. The problem is related to the fact that we have quite long loops doing texture reads. DirectX (HLSL) can't do that in real loops, so it forces loop unrolling. And it's too much.

We build a modified Angle library to try to reduce this problem. And it did: we achieved fast compilation (a couple seconds) of even our most complex shaders. But that was doing tricks not easily generalizable (as it is it would break some other applications). But there must be a way to do it safely. A We discussed these things and proposed a few options in the Angle Project mailing list.


Alvaro


El 06/04/2011 4:56, John Davis escribió:
I'm frustrated we are hamstringing the spec due to limitations on the mobile side.  The majority of web browsers out there are not being used on mobile devices.  Call me nuts, but this just doesn't make sense.

Look at the Web clients table.

Percentage-wise mobile web clients don't amount to squat.

On Tue, Apr 5, 2011 at 11:09 AM, Chris Marrin <cmarrin@apple.com> wrote:

On Apr 2, 2011, at 5:46 AM, John Davis wrote:

> >all of the extensions there are available on at least one OpenGL ES implementation on mobile devices (iPhone).
>
> Chris,
>
> Why does the above matter if WebGL is never going to be available on iPhone/iPad/AppleTV?  Why don't we focus on what IS available?

Are you just making a fatalistic complaint that you're unhappy with the fact that iOS devices don't publicly support WebGL today? Or did you get the impression from me or someone else that iOS will never support WebGL? If you interpreted something I said in that way, then I apologize. No one at Apple can comment on if or when WebGL will be available on iOS. If you've gotten that information from a blog somewhere then you should ignore it (as is a general rule about bloggers and Apple rumors).

-----
~Chris
cmarrin@apple.com







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