GLSL made some terrible design decisions IMHO, and there's no excuse since they could have simply just used HLSL/Cg and been done with it.
HLSL is not an standarized(in the concept of multiplatform/multivendor) thing... and is on that way due Microsoft monopoly and constant effort to own patents, private code, make things only for their own products like Windows and Xbox, abandon any dialog with the ARB cometee and Khronos, etc...
Cg is only well optimized and 100% compatible on NVIDIA cards.
GLSL have some good decisions too... but I agree, needs some modifications which, on the other hand, are in progress. But if you want to write good portable code for Windows, MacOSX, linux and Solaris.. there is only one option... OGL.
That's pretty funny, because many of the top-selling games support only a single platform
And could have even sell more if were more portable/multiplatform. Why to limit your business profit opportunities to an unique platform? (unless Microsoft is paying you a fortune for it or you're completely windozed ).
While quite a "noble" goal, it just isn't practical IMHO... I can count on one hand the number of PC games that use OpenGL, and personally I dislike all of them
Almost all of ID(doom3, quake 3, RtCW, quake 4, QWarsET ), MDK 2, Serious Sam, Sims 2, Prey, Sin 2, Kingpin, Rune, Soldier of Fortune, Descent 3, HeroesM&M, Second life, World of Warcraft, Eve online, Neverwinter nights, Knights of the Old Republic, [SIZE=-1]Chronicles of Riddick, Final Fantasy, GTA, Medal of Honor, Call of Duty, Unreal Tournament 3(expected but delayed atm), etc... a lot of PC games use/can use OpenGL... you should have malformed hands then...
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I think with OGL3 the number will grow even more. DX10 is becoming a complete selling fiasco and clearly slower than WinXP+DX9 by the moment, making laptop IHVs to protest to include the old WinXP because clients don't want Vista installed, etc... Good design but bad marketing decisions/portability perhaps...
Thus testing OpenGL performance is about as important as testing the exact rendering path of a particular game in my books... if you want to know how well Doom3 runs on your PC, download the demo and try it.
Well, if I could do a fast OGL speed test just checking an option in 3dm2008 will be good. I use 3dmark to know the approximate speed of my computer and GPU... but is clear to have better results you need to run various tests and real games/apps.
Real time global illumination
I think Humus can tell us more about using 10.1's cube map arrays to accelerate the GI.. after all he used cubemaps and SH for his GI demo.
Btw, Stepan uses OpenGL on his GI Lightsmark benchmark
http://www.opengl.org/news/permalink/lightsmark_opengl_20_benchmark_released/
without requiring Vista and neither DX10.1 ...