Perlin Noise Interpolates between cube-corners.
As higher dimensions are used this becomes computationally expensive compared to interpolating across equilateral triangles (simplexes).
For N-dimensional noise, there will be 2N cube corners but only N+1 simplex corners.
Consequently if you're going to be making animated clouds (time being the fourth dimension), this method is the one to use.
There are four methods for generating 1D to 4D noise, called Noise1, Noise2 etc.
The analytic derivative can optionally be calculated for flow animations, curl noise and analytic antialiasing.
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