Translate without affecting perspective
I'm putting together a simple visualization program using the fixed pipeline (I'm aware that it has been deprecated, but I need this to work on very old computers that may not have capable graphics cards).
I'm drawing the main object of interest in the center, using a perspective projection calculated using glFrustum, and I would like to draw a set of axes in the corner.
Problem is, I can't seem to think of a way to get it to appear using the same perspective projection (as if it were in the center) but translated to the corner. Any ideas?
Thanks in advance.
Use glViewPort to tell OpenGL that you want to draw into a small area in
the lower left corner of the window. Then draw your axes in the center
of that viewport.
Ah, I see. I should have taken a closer look at the documentation; I had assumed that glViewport specified some sort of mapping from scene coordinates to screen coordinates, but that was a mistake. I'll know not to make that sort of assumption in the future.
Thanks for your help!
EDIT: Just in case, I'll clarify for anybody who happens to read this: I thought glViewport mapped coordinates like glOrtho actually does.
Last edited by Aestivae; 11-23-2012 at 06:30 PM.