   Custom projection matrix
  How to make a frustum type projection matrix, but with the eye coordinate not in the (0, 0, 0)? I want to have a different values for x and y eye coords, z may stay 0. For example, I'd like to have a projection with eye coordinates (-0.5, 0.5, 0) to see the line going thru the screen in the middle of the upper left quarter of the screen as point (assuming the line is perpendicular to the screen plane). If it is not understandable, I could try to describe it better or post some schemes. Thanks   
  i've been wondering about this myself...   ;  Not sure I understood, but either you need to input some other values to the glFrustum function, or you need to apply some kind of scaling and translation to the modelview.   ;  Interesting. I think, that solution can be to apply some glTranslatef to Projection Matrix. But you have to normilize viewing volume in this case. I am not sure it is possible.   