I am in the process of porting a previous graphics lab to OpenGL (which happens to be our next lab!), but am hitting some snags.
While I was messing around with my projection dimensions, I noticed a pretty unusual relationship, and I don’t really understand it.
In order for me to see my object, my camera has to be located within the viewing volume defined in glOrtho() for a parallel projection. Why is this the case? I thought the glOrtho() function was only designed to specify the clipping parameters of the view-plane and it’s respective volume (with the Z parameters).
So now, when specifying my gluLookAt functions, my camera position (PRP) needs to be located somewhere inside the viewing volume that has been specified by glOrtho(). This really doesn’t make sense to me, since we have been taught that our camera simply maps everything inside the viewing volume against the view-plane, and the camera placement just specifies the direction of projection (DOP) to the view-plane from our fixed point in space.
Sorry if I am rambling, I’ve been staring at this problem for a good while now, and can’t really make any sense out of it. Thanks for any input!!