let radius = 300;

​

function setup() {

  createCanvas(400, 400);

}

​

function draw() {

  colorMode(HSB, 360, width, height);

  background(360, 0, height);

  var angleStep = 360 / segmentCount;

  beginShape(TRIANGLE_FAN);

  vertex(width/2, height/2);

  for(var angle=0; angle <= 360; angle+=angleStep){

    var vx = width/2 + cos(radians(angle)) * radius;

    var vy = height/2 + sin(radians(angle))*radius;

    vertex(vx, vy);

    fill(angle, mouseX, mouseY);

  }

  endShape();

}

​

function keyPressed() {

  if (key == 's' || key == 'S') saveCanvas(gd.timestamp(), 'png');

​

  switch (key) {

  case '1':

    segmentCount = 360;

    break;

  case '2':

    segmentCount = 45;

    break;

  case '3':

    segmentCount = 24;

    break;

  case '4':

    segmentCount = 12;

    break;

  case '5':

    segmentCount = 6;

    break;

  }

}