Barb Ericson Georgia Institute of Technology June 2007 Breakout in Greenfoot Barb Ericson Georgia Institute of Technology June 2007 Georgia Institute of Technology

Georgia Institute of Technology The Breakout Game Open Breakout-Start There are Bricks, a Message that says we are starting with Ball 1, a Ball, and a Paddle But if you click on act or run nothing happens Georgia Institute of Technology

Georgia Institute of Technology Game Rules Use the left and right arrow keys to move the paddle Use the paddle to hit the ball into the bricks to get rid of them Get rid of all the bricks to win the game The ball will bounce off most of the walls, paddle, and bricks You get up to three balls to use If you still have bricks after using 3 balls you lose If a ball hits the bottom wall it is removed and new ball added Georgia Institute of Technology

Georgia Institute of Technology Moving the Paddle Check if the left key is down Greenfoot.isKeyDown("left") if it is move left setLocation(getX() – moveAmount, y); else check if the right key is down Greenfoot.isKeyDown("right") if it is move right setLocation(getX() + moveAmount,y); Georgia Institute of Technology

Georgia Institute of Technology The Ball's Act Method Move the ball Check if hit any actors If hit an actor and that actor isn't the message Bounce off the object Check if the object was a brick if it was a brick remove the brick from the world and have the world check if the player won (no more bricks) Check if at any walls Bounce off top or side walls If at bottom wall remove ball and create a new one Georgia Institute of Technology

Georgia Institute of Technology Move the Ball The ball's y velocity is 3 but is a field velY The ball's x velocity should be a random value between 1 and 3 or -1 to -3 set in the constructor velX To move the ball add velX to the current x (getX) add velY to the current y (getY) Use setLocation(x,y); Georgia Institute of Technology

Checking if hit any Actors Get an actor (object of the class Actor) that intersects with this one Actor actor = this.getOneIntersectingObject(Actor.class); If the ball did hit an actor and it isn't the message (object of the Message class) if (actor != null && !(actor instanceof Message)) Georgia Institute of Technology

Bounce the Ball off an Actor The actor must be a paddle or a brick (if it isn't a message) So negate velY velY = -velY; Georgia Institute of Technology

Georgia Institute of Technology If the Ball hit a Brick Check using if (actor instanceof Brick) If the ball did hit a brick remove it world.removeObject(actor); check if won world.checkIfWon(); Georgia Institute of Technology

Georgia Institute of Technology Checking Walls If the ball hit the left wall if (getX() - radius <= 0) negate velX else If the ball hit the right wall if (getX() + radius >= BreakoutWorld.WIDTH) else If the ball hit the top wall else if (getY() - radius <= 0) negate velY Georgia Institute of Technology

Georgia Institute of Technology Checking Bottom Wall else if (getY() + radius >= BreakoutWorld.HEIGHT) remove the current ball from the world world.removeObject(this); add a new ball to the world world.newBall(); this also checks for the end of the game Georgia Institute of Technology

Georgia Institute of Technology Additional Ideas Add sounds bounce sound and win or lose sounds If hit at edge of paddle then bounce in x as well as y Speed up the velocity after each 7th hit double the x velocity See the documentation for the Greenfoot classes http://www.greenfoot.org/doc/javadoc/ Georgia Institute of Technology