isolines - OpenProcessing

mySketch
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const WIDTH = 750;
var time = 0;
var sintime;
var n = 700;
var first = true;
​
var glob_points = [];
var vert_lines = [];
var hor_lines = [];
for(let i = 0; i < n + 2; i++){
  glob_points.push([])
  vert_lines.push([]);
  hor_lines.push([]);
  for(let j = 0; j < n + 2; j++){
    glob_points[i].push(0);
    vert_lines.push([]);
    hor_lines.push([]);
  }
}
​
​
​
​
function setup() {
  createCanvas(WIDTH, WIDTH);
}
​
function draw() {
  noiseSeed(100);
  background(255);
  let steps = 50;
  
  let w = width/n;
  let h = height/n;
  let sf = 1/w/1000;
  sintime = sin(time)*0.2 + 1;
  for(let i = 0; i <= n+1; i++){
    for(let j = 0; j <= n+1; j++){
      glob_points[i][j] = findPoint(i, j, w, h, sf, steps);
    }
  }
  
  for(let i = 0; i <= n; i++){
    for(let j = 0; j <= n; j++){
      updateSides(i, j, first)
    }
  }
  
  first = false;
  
  
  push();
  let SC = 0.9;
  scale(SC);
  let off = 0.5*(1-SC)/SC * WIDTH
  translate(off, off);
  strokeWeight(2);
  noFill();
  for(let i = 0; i < n; i++){
    for(let j = 0; j < n; j++){
      drawCell(i, j, w, h, sf, steps);
    }
  }
  rect(0, 0, width, height)
  pop()
  time += 0.01*PI;
}
​
function drawCell(i, j, w, h, sf, steps){
  
  if(glob_points[i][j][3]){
    return;
  }
  
  
  
  
  
  let side1 = hor_lines[i][j];
  let side2 = vert_lines[i+1][j];
  let side3 = hor_lines[i][j+1];
  let side4 = vert_lines[i][j];
  
  let directions = [];
  
  
  
  let points = [].concat(side1[5], side2[5], side3[6], side4[6]);
  
  
  
  
  let stack = [points[0]];
  for(let k = 1; k < points.length; k++){
    let newp = points[k];
    let lastp = stack[stack.length-1];
    if(newp[1] === lastp[1]){
      stack.push(newp);
      continue;
    } 
    stack.pop();
    line(newp[0][0], newp[0][1], lastp[0][0], lastp[0][1]);
    if(stack.length == 0){
      k++;
      stack.push(points[k]);
    }
  }
  
  
  
  
  
}
​
​
function getSide(p1, p2){
  return [[p1[0], p1[1]], [p2[0], p2[1]], p1[2], p2[2], Math.abs(p1[2]-p2[2]), []];
}
​
function getHor(i, j){
  let p1 = glob_points[i][j];
  let p2 = glob_points[i+1][j];
  
  
  let side = getSide(p1, p2);
  getPoints(side);
  return side;
}
​
function getVert(i, j){
  let p1 = glob_points[i][j];
  let p2 = glob_points[i][j+1];
  
  
  let side = getSide(p1, p2);
  getPoints(side);
  return side;
}
​
​
function getPoints(side){
  
  let direction = 0;
  if(side[2] > side[3]){
    direction = 1;
  }
  for(let i=0; i < side[4]; i++){
    let t = 1-(i+1)/(side[4]+1);
    let negt = 1-t;
    side[5].push([[side[0][0]*t + negt*side[1][0],
                    side[0][1]*t + negt*side[1][1]],
                    direction]);
  }
  side[6] = [];
  for(let i = 1; i <= side[5].length; i++){
    let p = side[5][side[5].length - i];
    side[6][i-1] = [p[0], (p[1]+1)%2];
  }
  
}
​
function findPoint(i, j, w, h, sf, steps){
  let x1, y1;
  x1 = i*w; 
  y1 = j*w;
  let nois;
  nois = floor(noise(x1*sf, sintime*Math.cos(time + y1*sf*HALF_PI)+100, sintime*Math.sin(time+ y1*sf*HALF_PI)+100) * (steps));
  return([x1, y1, nois, false]);
}
​
function updateSides(i, j, go){
  let n1, n2, n3, n4;
      n1 = glob_points[i][j][2];
      n2 = glob_points[i+1][j][2];
      n3 = glob_points[i+1][j+1][2];
      n4 = glob_points[i][j+1][2];
      if( (n1 == n2) && (n2 == n3) && (n3 == n4) && (n4 == n1)){
        glob_points[i][j][3] = true;
      } else {
        glob_points[i][j][3] = false;
      }
      if(go){
        vert_lines[i][j] = getVert(i, j);
        hor_lines[i][j] = getHor(i, j);
        return;
      }
      if(n1 != vert_lines[i][j][2] || n4 != vert_lines[i][j][3]){
        vert_lines[i][j] = getVert(i, j);
      }
      if(n1 != hor_lines[i][j][2] || n2 != hor_lines[i][j][3]){
        hor_lines[i][j] = getHor(i, j);
      }
}