Anyone playing with the OpenGL Shading Laguage?

Member
Posts: 157
Joined: 2002.12
Post: #1
I came across a PDF online and I was just wondering if anyone have tryied it.
http://www.opengl.org/documentation/oglsl.html
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Sage
Posts: 1,232
Joined: 2002.10
Post: #2
Apple doesn't export GL_ARB_shading_language_100 yet.

On PCs this extension is supported only on Radeon 9500, GeForce 3, or newer.
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Moderator
Posts: 3,579
Joined: 2003.06
Post: #3
Which begs the question: Does anybody have any clue as to *when* it and it's supporting extensions will be implemented? I know this is not a question of "if" since they've already demonstrated that they're in hot pursuit of shading technology with stuff like OpenGL Shader Builder already on disk and CoreImage being demoed at WWDC. And then I wonder, to what extent? I certainly hope it'll be at least down to the Radeon 9000!

Shaders are still pretty new stuff, but I bought the orange book a few months ago to get a look-see at what's in store. It's going to be really, really interesting to see what comes out of this.
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Sage
Posts: 1,232
Joined: 2002.10
Post: #4
The supporting extensions ARB_fragment_shader, ARB_vertex_shader, and ARB_shader_objects were added in 10.3.4. GL_ARB_shading_language_100 is not there yet. Only Apple knows when.

The Radeon 9000 can't support ARB_fragment_program, only ATI_text_fragment_shader. So some shaders won't run on it, and without a software fragment program fallback, supporting GLSL on the Radeon 9000 is of dubious value. The software fragment program emulator is in 10.3.4, though, so I'm guessing it is only a matter of time before the fallback path is hooked up to the other renderers.
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Moderator
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Post: #5
Oh man, that blows... A software fallback doesn't seem to make much sense for shaders. So then the only practical way we'll get to mess with it is to spend several hundred dollars on a card upgrade or thousands to upgrade to a new mac? Great. I knew there was a reason I held off on that Radeon 9000 upgrade I was planning. What seemed like a great card at first now looks pretty useless other than more pipes and more memory. I can't imagine doing shaders outside of the OGL shading language in any practical sense. I guess we're all just going to have to wait and see what pans out. Thanks for the info arekkusu, keep us updated if you find out anything more.
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Sage
Posts: 1,232
Joined: 2002.10
Post: #6
Don't worry, everyone with a 9800 is going to have to upgrade to an 11800 to get FP blending. It's a never ending cycle.

The software fallback for vertex programs works OK for testing and developing, though you'd want to try to avoid it for games. Software fragment programs would be similar-- it'll let you see what the thing looks like on your hardware, even if it's not running at 100 fps.
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Member
Posts: 177
Joined: 2002.08
Post: #7
Software fragment programs perform far worse than software vertex programs do compared to their hardware equivalents. I doubt you'd get usable performance out of a nontrivial program running on software fragment programs, since that's for all intents and purposes a software-only renderer that doesn't use the GPU at all.
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Luminary
Posts: 5,143
Joined: 2002.04
Post: #8
You don't. In my experience on a decently grunty PC, about 30spf (seconds per frame).

Still, it's enough to see whether things look mostly right Smile
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