// http://forum.processing.org/topic/
// beginner-question-could-use-a-quick-response

final static byte NUM = 3;
final static Smiley[] smileys = new Smiley[NUM];

final static short FPS = 50, MAX_SPDX = 8, MAX_SPDY = 10;
final static color BG  = #0024FF;

// use JAVA2D for Processing 2+:
final static String ENGINE = P2D;

void setup() {
    size(500, 500, ENGINE);
    frameRate(FPS);

    for (int i=0; i!=NUM; smileys[i++] = new Smiley
    ( random(MAX_SPDX >> 1, MAX_SPDX), 
    random(MAX_SPDY >> 1, MAX_SPDY) ));
}

void draw() {
    background(BG);
    for (Smiley s: smileys)    s.script();
}

final class Smiley {
    short x, y;
    short dx, dy;

    static final short W = 50, WW = W >> 1, 
    WWW = W >> 2, W10 = W/10;

    static final short H = 80, HH = H >> 1, 
    HHH = H >> 2, H10 = H/10;

    static final color BRUSH = #FFFF50, TRACE = 0;

    Smiley(float spdX, float spdY) {
        dx = (short) spdX;
        dy = (short) spdY;

        x = (short) random(W, width  - W);
        y = (short) random(H, height - H);
    }

    void display() {
        fill(BRUSH);
        ellipse(x, y, W, H);

        noFill();
        arc(x, y, WW, HH, QUARTER_PI, QUARTER_PI*3);

        fill(TRACE);
        ellipse(x - WWW, y - HHH, W10, H10);
        ellipse(x + WWW, y - HHH, W10, H10);
    }

    void update() {
        if ( (x += dx) > width  - WW | x < WW )    dx *= -1;
        if ( (y += dy) > height - HH | y < HH )    dy *= -1;
    }

    void script() {
        display();
        update();
    }
}