I draw my terrain with triangle strips + VBOs and quadtrees. I also draw with lower level of detail if the quad is further away. At the mo' I copy *all* the lower res vertices of the quad again into a new place in the VBO. Is there a way of drawing a lower res version of the quad just by changing the parameters in glDrawElements ? The problem I can see with this is that if I sample say every other vertex in the VBO and draw with glDraw Elements triangle strips then the normals would all be wrong for each triangle as they haven't been defined in the normal array for these new lower res triangles. I'm just read the Focus on 3d terrain programming book and it basically calculates every triangle on the fly which seemed a bit of an overhead when we could use DrawElements or DrawArrays. Thanks Adrian