I have a very simple piece of terrain. it consists of a 3D plane with a ramp in the middle. i created the terrain in a modeler and exported it as a .obj. i then load the file into opengl and store all the information into an array and it displays fine. i can rotate it and move my simple square player around with no problems. my problems start when i want my player to move up the ramp. Is this a form of collision detection? I have no problem creating collision object that blocks the player from moving on the initial plane (assuming there is no jumping.