contains.js

var r = new Rune({
  container: "#canvas",
  width: 800,
  height: 600
});

var myPoly = r.polygon(400, 200)
  .lineTo(0, 0)
  .lineTo(200, 50)
  .lineTo(250, 60)
  .lineTo(200, 150)
  .lineTo(-200, 150)
  .lineTo(-250, 60)
  .lineTo(-200, 50)

for(var x = 0; x < r.width; x += 20) {
  for(var y = 0; y < r.height; y += 20) {
    if(myPoly.contains(x, y)) {
      r.circle(x, y, r.random(4, 10));
    }
  }
}

myPoly.removeParent();


r.draw();