float angle = 0.0;
float stepSize = 0.15;

int halfHeight, thirdHeight, sixthHeight, interval, startX, endX;

float proportion = 0.0;
float anoise = 0.0;

void setup() {
  size(640,480);
  lights();
  noStroke();
  halfHeight = height/2;
  thirdHeight = height/3;
  sixthHeight = height/6;
  interval = width/128;
  startX = width/10;
  endX = width - width/10;
}

void loop() {
  background(180,180,190);
  for (int i = startX; i < endX; i+=interval) {
    proportion = float(i)/width;
    anoise = 2*sin(proportion*PI);
    push();
    translate(i,halfHeight);
    rotateX(angle*proportion);
    rotateY(angle*proportion);
    rotateZ(angle*proportion);
    box(2,thirdHeight,2);
    pop();
  }
  if (!mousePressed) {
    angle+=stepSize*(mouseX-(width*0.5))/(width*0.5);
  }
  if (angle >= width*TWO_PI) {
    angle = 0.0;
  }
}

void mouseClicked() {
  stepSize*=-1.0;
}