I always booboo the spelling myself …
frustrum - Wiktionary, the free dictionary
1. Misspelling of frustum .
Denis was asking for 3D points of the corners of what (I think) are the near frustum plane ?
(… or did he want the corners of where the view frustum crosses the image plane ?)
These things and perhaps near and far clipping planes might be beneficial.
When writing library modules, wouldn’t it be better to define them as instance methods and put a call to
module_function at the top, so as to allow use either with qualified library method calls or mixing into modules and classes via include ?