Refactor: extract two drawing functions.
Add an alternate scene model drawing 2 flat planes at floor and ceiling.
Refactor: wrap each draw subroutine in a glUse and set uniform matrices.
Draw the floor and ceiling planes using a new shader.
Add the missing shader files for the planes. Use a poor-man's XOR in GLSL with sin, floor and an if for a checkerboard.
Invoke callbacks to change FBO size via Ant, the resolution tweak control is now live.