xnoise

float  xnoise(float x)

vector  xnoise(float x)

float  xnoise(float x, float y)

vector  xnoise(float x, float y)

float  xnoise(vector xyz)

vector  xnoise(vector xyz)

float  xnoise(vector4 xyzt)

vector  xnoise(vector4 xyzt)

Simplex noise is very close to Perlin noise, except with the samples on a simplex mesh rather than a grid. This results in less grid artifacts. It also uses a higher order bspline to provide better derivatives.

The various functions return the noise value at a 4D (vector4 argument), 3D (vector argument), 2D (two float arguments) or 1D (float argument) position. You can get a random float value or a vector of three random values.

The noise is in the range 0-1 with a median of 0.5. The distribution of the noise depends on the dimension, with higher dimensions approaching a Gaussian distribution of noise values.