I needed to rotate a set of line segments. Also i need the values of the transformed lines ends for some other calculations, I was wondering how I could determine those points. thanks for any help in advance
If you really do need the coordinates of a line segment after a certain rotation, that’s not something OpenGL will help you with. Take a look at 3D math, specifically matrices, vectors and multiplications thereof. Any good 3D book should at least give an introduction to this topic.
However, if you only want the new locations because you want to draw something there, let OpenGL to handle this for you. Read up on glPushMatrix/glPopMatrix and the effects of transformations on world coordinates. Search Google for information about displaying heirarchical models.