Hello,

I’m still discovering OpenGL, so sorry if I missed that part in the Big Red book!

For my application, I draw one 3D form 3 times. Each time, I use glOrtho to show an orthographic projection of the form. Now my problem is the following: is there a way to know what has been plotted in one of the 3 orthographic projections? My final goal would be to be able to add more stuff (such as text, lines, etc.) directly on the orthographic projection once it has been drawn.

So I imagined that by getting the coordinates of what is drawn after the glOrtho, I could just add stuff on it, but I can’t seem to find how to do that. Another solution would be to add the stuff I want to add before applying glOrtho, but that wasn’t my first intuition… would that be the way to go? And then, is there a way to compute myself where a point whose coordinates I know will be after I apply glOrtho to it?

Hope this is understandable and someone can point me in the right direction!

Sebastien