var N;

var cellHeight = 2;

var offset;

var deltaH = 40;

var pruneThreshold = 30;

var frame = 0;

​

let heights = [];

​

function setup() {

  createCanvas(500, 500);

  background(0);

  N = width/cellWidth;

  offset = width-100;

  for (i=0; i<N; i++) {

    heights[i] = 0;

  }

​

​

  //heights[N/2]=40;

}

​

function draw() {

  background(0);

  stroke(255);

  strokeWeight(2);

  frameRate(5);

  // the slow rate seems to be needed for the file saving to work right. 

  // 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();

  prune();

  if (frame < 1500) {

    print(nf(frame,4));

    saveCanvas(nf(frame,4),'png');

  }

  frame += 1;

}

​

function grow() {

  // here's the growing process

  x = floor(random()*N);

  if (random()<0.1) {

    heights[x]-=deltaH;

    //heights[x-1]+=deltaH/4;

    //heights[x+1]+=deltaH/4;

  }

​

}

​

function prune() {

  // average things out with some time

 //print(heights[height/2]);

​

  for (i = 0; i< N; i++) {

    heights[i]+=(heights[min(N-1,i+1)]+heights[max(0,i-1)]-2*heights[i])/(2*20);

  }

}

​

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);

  }

}

​