I've been trying to port HIVE to OpenGL for some time (multiple attempts). My biggest problem is the coordanate system. I would like HIVE to be consistant by always using the same coordanate system; origin in upper left, goes to width-1,height-1 in lower right. I've already tried doing calculations to convert, which works, but is terribly slow. Could someone show me how to instruct OpenGL to use a different coordinate system, or at least one that goes from 0,0 to width-1,height-1 (subtracting to get the new origin is quick).