Flattening 3D to 2D?

I have attempted a few various methods to flatten a 3D rendering to a 2D “blueprint”. My first instinct, of course, was to use glScalef. To my dismay, smaller z scale values tends to interfere with lighting.

Working with the premise there may not be a clean way to do this, is there a way to download all pixel information including hidden pixels (instead of merely visible pixels such as glReadPixels).

What I am trying to do seems like somewhat common need with technical drawings, but I have search high and low for a viable technique so far to no available.

Any guidance would be greatly appreciated. Thank you in advance.

Wat do you mean by “flatten”? If you don’t need perspective, just use an orthographic projection (glOrtho).

not understand all but think you want to take away one axis and project your 3d geometry on the plane (2d). anything you see on your screen is basically 2d converted from 3d and should give you some ideas. making one axis beeing zero should do it so you have only two axes.