glsl support on OS X

DesertPenguin
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Post: #1
I am developing a cross-platform OpenGL game for win/linux/mac. I am considering requiring glsl support. Is there decent glsl support on OSX? How many macs have hardware support for glsl?

Has there been improvements since OneSadCookie's 5/29/2005 blog "Macintosh OpenGL One Year On" assessment?

Or should I not expect glsl support and stick with the fixed-pipeline? I cannot support two render paths - not enough time.

Thanks for any feedback.....
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Sage
Posts: 1,199
Joined: 2004.10
Post: #2
OSC or Arekkusu can give you a better idea of GLSL support than I can, but: You *can* do GLSL on Macs as of 10.4.( 2 or 3 or 4, I don't remember ).

As far as I know, it's conformant, and works. I've not done any since I haven't purchased the orange book, and my powerbook's 5200 is pure shit.

As far as I know, all Macs will do GLSL, but depending on the video card, some may fall back to hardware. My guess would be all g5s, and the powerbooks. I don't know if the video card in iBooks and mac mini will do GLSL, my guess is that it won't ( though the integrated graphics in the new x86 mini claims shader support ).
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Member
Posts: 168
Joined: 2004.10
Post: #3
TomorrowPlusX Wrote:As far as I know, all Macs will do GLSL, but depending on the video card, some may fall back to hardware. My guess would be all g5s, and the powerbooks

I believe this is a mistype on TommorowPlusX's part, and to avoid any confusion, that should say "fall back to software". GLSL has been supported on software since 10.4, Tiger - and it has been supported on hardware since 10.4.2 iirc, if not, then 10.4.3. Most people that have Tiger will have upgraded anyway, as it is a free downloadable update.

So, yes, use GLSL.
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Luminary
Posts: 5,143
Joined: 2002.04
Post: #4
GLSL starts being useful in Mac OS X 10.4.3. If you can't require that as your minimum OS spec, you can't use GLSL.

The Mac GLSL implementation is pretty good, compared to ATI or NVidia's efforts on Windows and Linux. It's not without its flaws, but then, neither are the Windows drivers.

Hardware support is the same as Windows/Linux -- NVidia GeForce FX or better, ATI Radeon 9500 or better, Intel GMA 900 or better. Cards earlier than that will fall back to software, which is OK for vertex programs, but far too slow for fragment programs.

All currently shipping Mac models have a GLSL capable video card, however the immediately previous generation of Mac Mini does not, nor does the immediately previous generation of iBook. http://update.omnigroup.com/ may give you some idea of the proliferation of support. Look at the ARB_shading_language_100 extension.

As TomorrowPlusX notes, performance is highly dependent on the hardware. The GeForce FX 5200 in particular is very slow for shaders, and the GMA 950 in the new Mac Mini has half the number of temporary registers that the other cards do, and may require slightly simpler shaders. If you choose to go with GLSL, it will be a case of "test everywhere".
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Sage
Posts: 1,232
Joined: 2002.10
Post: #5
Of course if you don't go with GLSL, it is still a case of "test everywhere"...
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Luminary
Posts: 5,143
Joined: 2002.04
Post: #6
True 'nuff :/

At least with most other stuff there's hardwired limits (max texture size, etc) that you can look up online and be sure you're working within without having access to the hardware, though. With GLSL you're very much left guessing why a particular shader doesn't run in hardware.
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