Noise 2D

Calculates simplex noise along the XZ plane.

Inputs:

• pos: The position to calculate the noise at. The Y component of the position is effectively ignored.
• size: The scale of the noise. The bigger the value, the smaller the details of the noise.
• amplitude: The amplitude of the noise. The noise ranges from 0.0 to amplitude.
• lacunarity: How much the scale of the noise is multiplied by for each octave.
• gain: How much the amplitude of the noise is multiplied by for each octave.