Carmack's Reverse

From Free net encyclopedia

Carmack's Reverse is a computer graphics technique for stencil shadow volumes that solves the problem of when the viewer's "eye" enters the shadow volume by tracing backwards from some point at infinity to the eye of the camera. Although it was originally discovered by William Bilodeau and Michael Songy, who filed a patent for it in 1999, John Carmack discovered it independently in 2000 during the development of Doom 3 and is generally given credit for it since he, unlike Bilodeau and Songy, advertised his discovery to the larger public.

Incidentally, Creative Labs holds the patent and reached a deal with Id Software which allows Id Software to use the algorithm free of charge, in exchange for future support of EAX technology.

External links

• USPTO patent entry 6,384,822

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