How to mix realtime 3D graphics with a webcam scene using AR Toolkit.
1) the input webcam image, AR Toolkit grabs the cube's orientation and scale from this. Draw it into the back buffer with z-write off.
2) Align and render the stage using z-buffer writes but colour writes disabled.
3) Just for show, the 3D scene.
4) Render the 3D scene with z-reads on.. Enjoy your composite image!
