Noise interface and definitions :
vector freq = {1,1,1}; vector offset = {0,0,0}; float amp = 0; int turb = 5; float rough = 0.5; float atten = 1; onoise(@P*freq - offset, turb, rough, atten) * ampsnoise(@P*freq - offset, turb, rough, atten) * ampanoise(@P*freq - offset, turb, rough, atten) * amp vop_simplexNoiseVF(@P*freq - offset, turb, rough, atten) * amp vop_simplexNoiseVV(@P*freq - offset, turb, rough, atten) * amp vop_perlinNoiseVF(@P*freq - offset, turb, rough, atten) * amp vop_perlinNoiseVV(@P*freq - offset, turb, rough, atten) * amp copied from https://www.timucinozger.com/post/2015/07/24/noise-with-vex