Here are two papers from years 2003 and 2004. http://www-sop.inria.fr/reves/publications/data/2003/TGD03b/ntsingos_gamasutra2.pdf http://www-sop.inria.fr/reves/publications/data/2004/GT04/posterGP2.pdf
We should find out the critical date of the patent. Juhana -- http://music.columbia.edu/mailman/listinfo/linux-graphics-dev for developers of open source graphics software
