circle in a chess board

/**

 * circle in stripe

 * 

 * @author aadebdeb

 * @date 2017/06/18

 */

​

var BORDER_WIDTH = 10;

var ELLIPSE_SIZE = 350;

​

function setup() {

  createCanvas(windowWidth, windowHeight);

}

​

function draw() {

  blendMode(BLEND);

  background(255);

  noStroke();

  fill(0);

  var offset = -((frameCount % 30) / 30) * BORDER_WIDTH * 2;

  for (var h = offset; h < height; h += BORDER_WIDTH * 2) {

    rect(0, h, width, BORDER_WIDTH);

  }

  blendMode(DIFFERENCE);

  fill(255);

 for (var h = offset; h < height; h += BORDER_WIDTH * 2) {

     ellipse(width / 2, height / 2, h, h);

  }

  // ellipse(width / 2, height / 2, ELLIPSE_SIZE, ELLIPSE_SIZE);

}