"Thorsten Froehlich" <tho### [at] trfde> wrote in
news:3fa6367d@news.povray.org: 

> No, you got fooled by the style the paper is written in.  If you read
> it carefully, you will notice they only talk about a simulation.  They
> have not actually implemented it, they just wrote a simulator that
> shows it could be possible.  All their figures are based on that
> simulator! 

You are referring to the paper "Ray Tracing on Programmable Graphics 
Hardware" that dates back to 2002 when no hardware met the authors 
requirements.

In the successive paper "Photon Mapping on Programmable Graphics Hardware", 
however, the authors make use of "...a stochastic ray tracer written using 
a fragment program. The output of the ray tracer is a texture with all the 
hit points, normals, and colors for a given ray depth." (citation from 
chapter 2.4) and their prototype application runs on "... a GeForce FX 5900
Ultra and a 3.0 GHz Pentium 4 CPU with Hyper Threading and 2.0 GB RAM. The 
operating system was Microsoft Windows XP, with version 43.51 of the NVIDIA 
drivers. All of our kernels are written in Cg and compiled with cgc version 
1.1 to native fp30 assembly." (citation from chapter 3).

Anyway, my point was not to praise the gpu approach to gpu but simply to 
answer the poster that ray tracing on gpu is possible with some 
limitations. Both papers are a "proof of concept" and to see practical 
applications (likely not substituting traditional rendering) we will have 
to wait and see. I mainly got the impression that commodity hardware 
raytracing is "around the corner".
--

Alessandro

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