Sabrina Kilian escreveu:
> nemesis wrote:
>> In any cases, you get it wrong:  the amazing speed up is not due to
>> native GPU triangle handling, but faster ray intersection calculations
>> thanks to the GPU sheer parallel vector processing.  You can see that in
>> smallptGPU where you get perfect math spheres much faster, no meshes in
>> sight.
>>
> 
> Spheres are the other special, easy, case. Any ray that comes within
> -radius- of -center point- must intersect the sphere, with a surface
> normal that is pretty easy to compute. From that, the diffuse,
> reflection, and so on. The math, as obvious by the very short
> intersection code in smallpt, is easy and compact.
> 
> Now, for any given cone, with arbitrary rotation and ratio of base to
> height, provide a fast general case for the ray intersection test, that
> will give you the same information. Single test, just to be clear, not
> separate cases for the disc bottom and cone top.
> 
> Then cube, then spline lathe, SOR, blobs . . .

It's an example that the speedup is independent of the native GPU 
triangle handling, nothing more.

I'm not math competent at all to give an answer to that.

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