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Friday, August 24, 2007

Ray Tracing Shading Language

Steve Parker and friends at Utah have developed a ray tracing shading language (RTSL) described in this pdf file. I am very excited about this work for entirely selfish reasons. I like ray tracing partially because of the elegant code. Now add ray packets and SSE and voila-- it makes DirectX code look lovely in comparison. The initial results are that ray packets and SSE can be relegated to a compiler with little or no loss of performance. and the code is pretty sweet looking. I have been looking over the shoulder of this project writing some RTSL code and it really seems to work as well as reported in the paper. A surprise to me is that it is much nicer to write than C++ for me because you avoid the blasted C++ header files.

Monday, August 13, 2007

Grid creation paper

Here is a pdf file of a new paper by Thiago Ize, Steve Parker, and myself. It will appear in Ulm at RT07 It does some theory on how to build grids within grids. It is a follow-on to the classic Jevans and Wyvill paper. Its main practical result is that for a two level grid of small triangles, use N**(1/5) subdivisions in each dimension, and then in occupied cells use M**(1/3) where M is the number of primitives in that cell. For single ray code this seems to work quite well. There is also some analysis for long-skinny triangles (like you might get subdividing a cylinder) which says grids are bad at such scenes. That being said, BVH with AABB and k-d are probably even worse!

Friday, August 10, 2007

Results of new poll in

This poll was better designed but still had one big flaw-- should have had more years-- people clumped in 2011.

For those readers that have not done a ray tracer I recommend Suffern's new book. He covers a ton of details that are not in other books. I saw a copy at SIGGRAPH and it lives up to the potential shown by all those chapters he's let me use in classes over the years.

Friday, August 3, 2007

New poll

Well people are clearly divided on the last poll. But as pointed out it was ambiguous so here's a new poll that is more straightforward.