var xoff, yoff;



var time;



var colors = [];



function setup() {

  createCanvas(700,700);

  background(238, 238, 238);



  noFill();

    

  colors.push(color(135,206,235,128))

  colors.push(color(100,149,237,128));

  colors.push(color(0,0,128,128));

  colors.push(color(95,158,160,128));





  xoff = 0.0;

  yoff = 0.0;

  

  time = 0;

}



function draw() {



  var c = getColor(time);

  stroke(c);



  beginShape();

  var xoff = 0;

  for (var x = 0; x <= windowWidth; x += 2) {

    var y = map(noise(xoff, yoff), 0, 2, 0, windowHeight);

    curveVertex(x, y);

    xoff += 0.05;

  }

  yoff += 0.02;

  curveVertex(windowWidth,

               windowHeight);

  endShape();

  

  time = time + 0.001;



  if (time > 1.0) {

    time = 0;

  } 

}



function getColor(t) {

  var p = t * (colors.length - 1);

  var from = floor(p);

  return lerpColor(colors[from], colors[from + 1], p - from);

}