Rotate 1

/**
 * Rotate 1. 
 * 
 * Rotating simultaneously in the X and Y axis. 
 * Transformation functions such as rotate() are additive.
 * Successively calling rotate(1.0) and rotate(2.0)
 * is equivalent to calling rotate(3.0). 
 */
 
float a = 0.0;
float rSize;  // rectangle size

void setup() {
    size(640, 360, P3D);

    rSize = width / 6;

    noStroke();
    fill(204, 204);
}

void draw() {
    background(126);

    a += 0.005;

    if (a > TWO_PI) {
        a = 0.0;
    }

    translate(width / 2, height / 2);

    rotateX(a);
    rotateY(a * 2.0);

    fill(255);
    rect(-rSize, -rSize, rSize * 2, rSize * 2);

    rotateX(a * 1.001);
    rotateY(a * 2.002);

    fill(0);
    rect(-rSize, -rSize, rSize * 2, rSize * 2);
}