/*
 * Bouncing Balloons
 
 * forum.processing.org/topic/using-arrays-to-create-and-change-circles
 * http://forum.processing.org/topic/object
 * http://forum.processing.org/topic/balloon-string
 
 * studio.processingtogether.com/sp/pad/export/ro.9FqnMDLUZqQCV/latest
 
 */

private static final color bg = 0, fg = 255;
private static final byte  fps = 50;

private static final byte ellipNum = 3;
private static final myBalloon[] balloons = new myBalloon[ellipNum];

final void setup() {
    size (500, 500);
    smooth();
    frameRate(fps);

    balloons[0] = new myBalloon(
    120, 70, // initX, initY
    50, 40, // sizeX, sizeY
    7, 1, // moveX, moveY
    #0000FF); // colour

    balloons[1] = new myBalloon(
    320, 400, // initX, initY
    40, 50, // sizeX, sizeY
    2, -9, // moveX, moveY
    #00FF00); // colour

    balloons[2] = new myBalloon(
    250, 250, // initX, initY
    30, 30, // sizeX, sizeY
    -7, 4, // moveX, moveY
    #FF0000); // colour
}

final void draw() {
    background(bg);

    for ( byte idx=ellipNum; idx>0; balloons[--idx].all() );
}

private final class myBalloon {
    int x, y;
    int szX, szY;
    int mvX, mvY;
    color cor;

    myBalloon (
    int initX, int initY, 
    int sizeX, int sizeY, 
    int moveX, int moveY, 
    color colour ) {

        x   = initX;
        y   = initY;
        szX = sizeX;
        szY = sizeY;
        mvX = moveX;
        mvY = moveY;
        cor = colour;
    }

    private final void all() {
        update();
        display();
        strDisplay();
    }

    private final void update() {
        if ( x < (szX>>1) || x > width  - (szX>>1) )    mvX *= -1;
        if ( y < (szY>>1) || y > height - (szY>>1) )    mvY *= -1;

        x += mvX;
        y += mvY;
    }

    private final void display() {
        noStroke();
        fill(cor);
        ellipse(x, y, szX, szY);
    }

    private final void strDisplay() {
        stroke(fg);
        line( x, y+(szY>>1), x-mvX, y+szY );
    }
}