Help ?poly labeling?

I don''t know what the hell this would be called, but i need help with it. You see im working on an engine, and the intent is to put this into making a skating game. Now, i don''t really know how this should be done....i''m a noob to OpenGL(not programming, only opengl) so i don''t know alot. I need a way to for example tell the game which polygons in the level can be grinded on. I''m not sure how this would work...so im asking.... Thanx in advanced. -------------------------- |FuK| Ghost Face Killa You Got Fucked By Fuk! --------------------------