/* built with Studio Sketchpad: 
 *   https://sketchpad.cc
 * 
 * observe the evolution of this sketch: 
 *   https://playgramming.sketchpad.cc/sp/pad/view/ro.bFqnaFxueYj/rev.22
 * 
 * authors: 
 *   Devon Scott-Tunkin

 * license (unless otherwise specified): 
 *   creative commons attribution-share alike 3.0 license.
 *   https://creativecommons.org/licenses/by-sa/3.0/ 
 */ 



// Processing Book, Casey Reas, pg. 282 Motion 1: Lines, Curves

float d = 20.0;
float speed = 1.0;
int direction = 1;

void setup() {
    size(100, 100);
    smooth();
    noStroke();
    fill(255, 204);
}

void draw() {
    background(0);
    ellipse(0, 50, d, d);
    ellipse(100, 50, d, d);
    ellipse(50, 0, d, d);
    ellipse(50, 100, d, d);
    d += speed * direction;
    if ((d > width) || (d < width/10)) {
        direction = -direction;
    }
}