this sketch is experimentation to control perlin noise waves in two dimension.
you can change some parameters.
"distance" controls distances of between a wave and next wave in perlin noise space.
"divide" controls how many divides do each wave have.
"number" : how many waves.
"position" : whole location in Y axis.
"gain" : noise function is provide a number from 0 upto 1.0(sometime more than 1.0) , so it needs gain for displyable.
"length" : difficult to explain. but easy to see.
"speed" : speed is determined by code like " tan( noise(n) ) * speed " , i love tangent and perlin noise.