http://ludonaut.tumblr.com/post/82277895432

pinwheel.pde

float a;

void setup() {
  size(500, 500, P2D);
  blendMode(BLEND); // also try LIGHTEST, MULTIPLY, SCREEN
  smooth(8);
  colorMode(HSB, 360);
  noFill();
  strokeWeight(10);
}

void draw() {
  background(100);
  translate(width/2, height/2);
  rotate(0);

  float wav1 = map(sin(a), -1, 1, -12, 12); // growth
  float wav2 = map(sin(a), -1, 1, -20, 20); // rotation

  // 20 tris
  for (int i = 1; i < 20; i++) {
    float d = map(i, 1, 20, 1.0, wav1);
    float t = map(i, 1, 20, wav2, 0.1);

    // colors
    float deg = map(i, 1, 20, 1, 360);
    stroke(deg, 200, 360);

    triangle(
    sin(radians(i*t))*(i*d), cos(radians(i*t))*(i*d), 
    sin(radians(i*t+240))*(i*d), cos(radians(i*t+240))*(i*d), 
    sin(radians(i*t+120))*(i*d), cos(radians(i*t+120))*(i*d)
    );
  }
  
  // TWO_PI/120 = 0.0523
  // instead of 0.05 for perfect loop.
  a+=0.0523;
}