scott wrote:
>>> I was thinking more about how to store the scene on the GPU 
>>> efficiently, if you just have a triangle list it is relatively simple.
>>
>> Again, depends on whether you're writing a shader, or using a GPGPU 
>> system.
> 
> It still runs on the same hardware though, which is highly optimised for 
> graphics operations, you need to be aware of this no matter how you 
> shape your code.

Sure. I'm just saying GPGPU gives you a little more freedom (at the cost 
of, currently, being manufacturer-specific).

>> But they don't allow recursion.
> 
> Yes that was what I said earlier, for something like raytracing to 
> unlimited depths I think the CPU needs to step in every so often to 
> process the current set of rays (ie kill and spawn rays where appropriate).
> 
> Of course if you want to limit yourself to a fixed depth (ie a max trace 
> level of 8 or whatever) then you can "unroll" the recursion so it works 
> on the GPU.  Might not be as efficient as letting the CPU do it though.

I'm just thinking that if the CPU has to intervine that much, the PCI 
bus is rapidly going to become a bottleneck to the whole system.

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