var N;

var cellHeight = 2;

var offset;

var deltaH = 5;

var pruneThreshold = 30;

​

let heights = [];

​

function setup() {

  createCanvas(500, 500);

  background(0);

  N = width/cellWidth;

  offset = width/2;

  for (i=0; i<N; i++) {

    heights[i] = 0;

  }

​

}

​

function draw() {

  background(0);

  stroke(255);

  strokeWeight(2);

​

  // now loop through

  for (i=0; i<N; i++) {

    line(i*cellWidth, offset+(heights[i]*cellHeight),(i+1)*cellWidth,offset+(heights[i]*cellHeight)); // horizontal line

    if (i>=1)

      line(i*cellWidth,offset+(heights[i-1]*cellHeight),i*cellWidth,offset+(heights[i]*cellHeight)) // vertical line

  }

  grow();

  pruneNew();

}

​

function grow() {

  // here's the growing process

  x = floor(random()*N);

  heights[x]-=deltaH;

  if (x>0)

    heights[x-1]+=deltaH/4;

  if (x<N)

    heights[x+1]+=deltaH/4;

}

​

function prune() {

  // look for high gradients and prune them with some probability

​

  for (i=1; i<N; i++) {

    /*if (abs(heights[i]-heights[i-1])>pruneThreshold) {

      if (random() < 0.5) {

        heights[i] = (2*heights[i]+heights[i-1])/3;

        heights[i-1] = (heights[i]+2*heights[i-1])/3;

      }

    }*/

    if (abs(heights[i])>(pruneThreshold)) {

      if (random() < 0.5) {

        heights[i] = 0

      }

    }

  }

}

​

function pruneNew() {

  pruneWidth = 10;

  if (random() < 0.1) {

    // randomly choose the center of the pruning. 

    print("Prune");

    x = floor(random()*N);

    for (i = max(x,0); i<min(x+pruneWidth,N); i++) {

      heights[i]=0;

    }

    stroke(255,0,0);

    //line(i*cellWidth,offset,(i+pruneWidth)*cellWidth,offset);

  }

}

​