var points = [];

var posX, posY;

var speedX;

var yoff;



var colors = [];

var time;



function setup() {

  createCanvas(windowWidth,

               windowHeight);

  angleMode(DEGREES);

  fill(300, 300, 300);

  background(238, 238, 238);

  

  time = 0;



  posX = 0;

  posY = windowHeight / 2;

  speedX = 0.5;

  yoff = 0.0;



  colors.push(color(155, 160, 250, 230));

  colors.push(color(200, 200, 250, 128));

  colors.push(color(255, 160, 225, 128));

  colors.push(color(255, 100, 105, 128));

  colors.push(color(200, 25, 70, 128));

  colors.push(color(95, 25, 55, 128));

  

}



function draw() {

  points = [];

  var n = 36;

  var theta = 360 / n;

  var radius = windowHeight / 3;

  var xoff = 0.0;

  for (var i = 0; i < n; i = i + 1) {

    var amp = noise(xoff, yoff);

    points[i] = {

      x: amp * radius * cos(i * theta),

      y: amp * radius * sin(i * theta)

    }

    xoff = xoff + 0.2;

  }

  yoff = yoff + 0.5;



  posX = posX + speedX;

  posY = height / 12 * cos(360 * posX / width) + height / 2;



  for (var i = 0; i < n; i = i + 1) {

    points[i].x += posX;

    points[i].y += posY;

  }



  stroke(getColor(time));

  fill(255, 255, 255, 5);



  beginShape();

  for (var i = 0; i < points.length; i = i + 1) {

    curveVertex(points[i].x, points[i].y);

  }

  curveVertex(points[0].x, points[0].y);

  curveVertex(points[1].x, points[1].y);

  curveVertex(points[2].x, points[2].y);

  endShape();



  time += speedX / windowWidth;

}



function getColor(t) {

  t = constrain(t, 0.000, 0.9999);

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

  var from = floor(p);

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

}