var pointX = [];

var pointY = [];

var speedX = [];

var speedY = [];



function setup() {

  createCanvas(windowWidth,

               windowHeight);

	strokeWeight(5);

  for (var i = 0; i < 4; i = i + 1) {

    pointX[i] = random(0, windowWidth);

    pointY[i] = random(0, windowHeight);

    speedX[i] = random(-5, 5);

    speedY[i] = random(-5, 5);

  }

}



function draw() {

  background(234, 234, 234, 20);

    

  for (var i = 0; i < 4; i = i + 1) {

    pointX[i] = pointX[i] + speedX[i];

    pointY[i] = pointY[i] + speedY[i];



    if (pointX[i] > windowWidth || pointX[i] < 0) {

      speedX[i] = -speedX[i];

    }

    

    if (pointY[i] > windowHeight || pointY[i] < 0) {

      speedY[i] = -speedY[i];

    }

  }



  square();

}



function square() {

  stroke(110, 250, 240);

  line(pointX[0], pointY[0], pointX[1], pointY[1]);

  stroke(130, 200, 245)

  line(pointX[1], pointY[1], pointX[2], pointY[2]);

  stroke(150, 145, 250);

  line(pointX[2], pointY[2], pointX[3], pointY[3]);

	stroke(110, 175, 230)

  line(pointX[3], pointY[3], pointX[0], pointY[0]);

}