I'm not going to comment on patents here, but you're absolutely wrong in assuming that implementing an optimized algorithm is trivial, especially in real-time graphics.
Sure, coding up B-trees from a textbook description is easy. But in a video game, 10fps and 30fps is the difference between unplayable and perfect, which means that your "by the book" implementation likely won't cut it. Video game developers spend months squeezing the last 1.1x improvements out of their inner loops, using clever bit coding techniques, cache alignment, often even hand-optimized assembler.
Sure, coding up B-trees from a textbook description is easy. But in a video game, 10fps and 30fps is the difference between unplayable and perfect, which means that your "by the book" implementation likely won't cut it. Video game developers spend months squeezing the last 1.1x improvements out of their inner loops, using clever bit coding techniques, cache alignment, often even hand-optimized assembler.