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> Yeah, I'm reading about it now. (Hmm, I guess I'm not the only person who
> still thinks 512 MB RAM is a lot. ;-)
For a games console it's probably enough. What do you hold in RAM during a
game? All the 3D meshes and textures are on the GPU video memory only*.
Probably only the code, collision meshes, map data? And the PS3 OS is
vastly simpler than Windows, so I doubt that uses up much RAM.
* When you write a game under Windows, you must keep all the GPU data
mirrored in normal RAM, because if the user Alt-Tabs to a different 3D game,
you need to refill the GPU memory quickly (and not go through some long
load-from-disk process) when the user comes back to your app. On a games
console you don't need to do this, because (at least on the PS3) you have to
quit one game before you can go into another.
> It's a completely different algorithm to be sure. The mathematics is
> simple enough - it's figuring out how to make it efficient on real-world
> hardware that's the hard part. ;-)
There was a nice paper I read in a book a while back (one of the GPU gems
series I think), where some algorithm was explained for doing correct
multi-level reflections on the GPU. It was quite complex, involving
generating lots of cube-maps with depth and texture information and some
ray-tracing steps in a pixel shader. In the end they compared the output
with a real raytracer, and the results looked identical, but the GPU version
ran at about 10fps IIRC with something like 4 levels of reflection. The
real raytracer (Maya I think) was measured in minutes.
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