For the Gl ortho call for the fbo, I swapped the Z planes around and then set the depth func to LEQUAL. it now seems to draw to the texture such that I can see it.  However, anything drawn at a z position greater than 0 is invisible, and when I draw the boxes such that they overlap even in the slightest, only the box drawn later is visible (with the one being drawn first becoming completely invisible).  We're making progress!  Though we're not quite there yet.

[edit] For now, I'm going to leave the main scene ortho the way it is, as it has always worked before.  I wonder if the reason it works the way I expect is because of the camera view angle.  Anyway, that's unimportant at the moment.

For the Gl ortho call for the fbo, I swapped the Z planes around and then set the depth func to LEQUAL. it now seems to draw to the texture such that I can see it.  However, anything drawn at a z position greater than 0 is invisible, and when I draw the boxes such that they overlap even in the slightest, only the box drawn later is visible (with the one being drawn first becoming completely invisible).  We're making progress!  Though we're not quite there yet.