Incorrect names

[amaranth]

Your Noise.gradientCoherentNoise3D is actually Perlin noise and your Perlin noise is actually fBM noise. libnoise made this mistake and since everyone else is either porting that library or copy/pasting from it this is a pretty widespread mix up.

https://en.wikipedia.org/wiki/Perlin_noise
https://en.wikipedia.org/wiki/Fractional_Brownian_motion
https://iquilezles.org/www/articles/fbm/fbm.htm