It all depends on how the court sees it. See "Carmack's Reverse" - where John Carmack independently developed an acceleration for robust stencil shadows, docum

It all depends on how the court sees it. See "Carmack's Reverse" - where John Carmack independently developed an acceleration for robust stencil shadows, documented his discovery and then had to capitulate to Creative Labs who owned a patent on the algorithm from a few months earlier.