glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(60, 640/480, 1, 100);

What Point is the top left of the screen? How do I tell what the maximum value of the frustrum for the top, right, etc.? It's really giving me a head ache. I don't see how to effectively use gluPerspective.

For example: How do I know whether to use really small numbers or really big ones when creating primtives in my scene?

Oh and, seeing as the Viewing Frustrum can move around and such, is the OpenGL entire coordinate system, is there a maximum value you can place on object on the y-axis (or any other axis) e.g. MAX_DOUBLE or something? S:

Is there a way to set up my coordinate system to a Cube with the size of 1000 units. (NOT the viewing frustrum just the coordinate system, or something). Also, is there a way to have a function somewhat similar to gluPerspective and glFrustrum so I can set the length of the sides (i.e. width/height of the frustum) or something (I doubt this is possible, but worth asking).

Sorry that this may seem like a really nooby question but I am EXTREMELY confused (and sorry if some parts made abosolutely no sense at all).