I’ve seen this _more than once_ and always seem to look to the wrong things..
# Problem: patchy renders
# Diagnosis: Eye is TOO CLOSE to the surfaces when rendering hemicubes.
– turn OFF backface rendering (CULL THE BACKFACES!!)
– move the eye 1e-9 units in the direction of the eyeToLook vector (to move it JUST ABOVE the surface of the patch you are getting the hemicube for)