First,in OpenGL, when you define the clip planes with glFrustum, do the clip planes reside in world space, or camera space? I mean, if you set the clip plane to -20 along Z, if you move the camera to (0,0,-20) , does the clip apply to -40 (because the camera moved) or to -20? So is it camera bound or not?
Second, what is the difference between calling glFrustum and then gluLookAt and calling first gluLookAt and then glFrustum?
Third, do the normals apply to surfaces or vertices? for example, if you make a pyramid, the normals for the surfaces are easy to calc, but if the normals are for vertices, every normal is a bit strange... Besides, a vertex shouldn't have a normal, right? only a plane should.