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// This file is part of www.nand2tetris.org
// and the book "The Elements of Computing Systems"
// by Nisan and Schocken, MIT Press.
// File name: projects/11/Pong/PongGame.jack
/**
* Represents a Pong game.
*/
class PongGame {
static PongGame instance; // the singelton, a Pong game instance
field Bat bat; // the bat
field Ball ball; // the ball
field int wall; // the current wall that the ball is bouncing off of.
field boolean exit; // true when the game is over
field int score; // the current score.
field int lastWall; // the last wall that the ball bounced off of.
// The current width of the bat
field int batWidth;
/** Constructs a new Pong game. */
constructor PongGame new() {
do Screen.clearScreen();
let batWidth = 50; // initial bat size
let bat = Bat.new(230, 229, batWidth, 7);
let ball = Ball.new(253, 222, 0, 511, 0, 229);
do ball.setDestination(400,0);
do Screen.drawRectangle(0, 238, 511, 240);
do Output.moveCursor(22,0);
do Output.printString("Score: 0");
let exit = false;
let score = 0;
let wall = 0;
let lastWall = 0;
return this;
}
/** Deallocates the object's memory. */
method void dispose() {
do bat.dispose();
do ball.dispose();
do Memory.deAlloc(this);
return;
}
/** Creates an instance of Pong game, and stores it. */
function void newInstance() {
let instance = PongGame.new();
return;
}
/** Returns the single instance of this Pong game. */
function PongGame getInstance() {
return instance;
}
/** Starts the game, and andles inputs from the user that control
* the bat's movement direction. */
method void run() {
var char key;
while (~exit) {
// waits for a key to be pressed.
while ((key = 0) & (~exit)) {
let key = Keyboard.keyPressed();
do bat.move();
do moveBall();
do Sys.wait(50);
}
if (key = 130) { do bat.setDirection(1); }
else {
if (key = 132) { do bat.setDirection(2); }
else {
if (key = 140) { let exit = true; }
}
}
// Waits for the key to be released.
while ((~(key = 0)) & (~exit)) {
let key = Keyboard.keyPressed();
do bat.move();
do moveBall();
do Sys.wait(50);
}
}
if (exit) {
do Output.moveCursor(10,27);
do Output.printString("Game Over");
}
return;
}
/**
* Handles ball movement, including bouncing.
* If the ball bounces off a wall, finds its new direction.
* If the ball bounces off the bat, increases the score by one
* and shrinks the bat's size, to make the game more challenging.
*/
method void moveBall() {
var int bouncingDirection, batLeft, batRight, ballLeft, ballRight;
let wall = ball.move();
if ((wall > 0) & (~(wall = lastWall))) {
let lastWall = wall;
let bouncingDirection = 0;
let batLeft = bat.getLeft();
let batRight = bat.getRight();
let ballLeft = ball.getLeft();
let ballRight = ball.getRight();
if (wall = 4) {
let exit = (batLeft > ballRight) | (batRight < ballLeft);
if (~exit) {
if (ballRight < (batLeft + 10)) { let bouncingDirection = -1; }
else {
if (ballLeft > (batRight - 10)) { let bouncingDirection = 1; }
}
let batWidth = batWidth - 2;
do bat.setWidth(batWidth);
let score = score + 1;
do Output.moveCursor(22,7);
do Output.printInt(score);
}
}
do ball.bounce(bouncingDirection);
}
return;
}
}
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