i have a problem. im trying to have an extra file to put all my objects into, but whenever i try to use one of the objects, which is a function, it says it can't be found. im using opengl. the real question im asking pretty much how do you use functions in one cpp file from another cpp file, do you need to use .cpp or .h?

http://www.gamedev.net/reference/articles/article1798.asp