For those having problems with the Invalid_Operation Error: Try this
in godrays.glsl there is a line with this:
const int NUM_SAMPLES=100;
change it to something lower, for me it works until i get over 70.
in godrays.glsl there is a line with this:
const int NUM_SAMPLES=100;
change it to something lower, for me it works until i get over 70.