Talking about Ballz game, Game development, HTML5, Javascript and Phaser.
We are going to start the new year with a new tutorial series, this time we’ll see how to create a HTML5 version of Ballz by Ketchapp Studio.
It’s an interesting take to the brick breaker genre, with easy and intuitive controls as you should expect from any mobile game.
Before we start coding, let’s have a look at the game area:
We are going to use ARCADE physics to handle the game. We don’t need any complex engine like Box2D because this game does not feature friction, gravity, or realistic collision detection, so we are using the simplest physics engine Phaser provides.
In this first part, we are going to create the game field, the ball, the fake predictive trajectory and the player interaction as well as the physics involved in launching the ball.
Have a look at the result:
Tap/click and drag to the bottom to aim the ball, release to launch it.
If you have a mobile device, you can play it directly from this link.
And this is the completely commented source code, the entire prototype was made in 80 lines of code, which is quite awesome:
// the game itself
var game;
// global options
var gameOptions = {
// score panel height / game height
scorePanelHeight: 0.08,
// launch panel height / game height
launchPanelHeight: 0.18,
// ball size / game width
ballSize: 0.04,
// ball speed, in pixels/second
ballSpeed: 1000
}
// when the window loads...
window.onload = function() {
// game creation
game = new Phaser.Game(640, 960, Phaser.CANVAS);
// add "PlayGame" state and execute it
game.state.add("PlayGame", playGame, true);
}
// "PlayGame" state
var playGame = function(){}
playGame.prototype = {
// when the state preloads
preload: function(){
// load graphic assets
game.load.image("ball", "ball.png");
game.load.image("panel", "panel.png");
game.load.image("trajectory", "trajectory.png");
},
// once the state has been created
create: function(){
// scale and background settings
game.scale.scaleMode = Phaser.ScaleManager.SHOW_ALL;
game.scale.pageAlignHorizontally = true;
game.scale.pageAlignVertically = true;
game.stage.backgroundColor = 0x202020;
// start ARCADE physics system
game.physics.startSystem(Phaser.Physics.ARCADE);
// place score panel
var scorePanel = game.add.image(0, 0, "panel");
scorePanel.width = game.width;
scorePanel.height = Math.round(game.height * gameOptions.scorePanelHeight);
// place launch panel
this.launchPanel = game.add.sprite(0, game.height, "panel");
this.launchPanel.width = game.width;
this.launchPanel.height = Math.round(game.height * gameOptions.launchPanelHeight);
this.launchPanel.anchor.set(0, 1);
// enable ARCADE physics on launch panel
game.physics.enable(this.launchPanel, Phaser.Physics.ARCADE);
// launch panel will not move
this.launchPanel.body.immovable = true;
// place the ball
var ballSize = game.width * gameOptions.ballSize;
this.ball = game.add.sprite(game.width / 2, game.height - this.launchPanel.height - ballSize / 2, "ball");
this.ball.width = ballSize;
this.ball.height = ballSize;
this.ball.anchor.set(0.5);
// enable ARCADE physics on the ball
game.physics.enable(this.ball, Phaser.Physics.ARCADE);
// the ball will collide on bounds
this.ball.body.collideWorldBounds=true;
this.ball.body.bounce.set(1);
// place the trajectory
this.trajectory = game.add.sprite(this.ball.x, this.ball.y, "trajectory");
this.trajectory.anchor.set(0.5, 1);
this.trajectory.visible = false;
// wait for player input
game.input.onDown.add(this.aimBall, this);
game.input.onUp.add(this.shootBall, this);
game.input.addMoveCallback(this.adjustBall, this);
// the player is not aiming
this.aiming = false;
// the player is not shooting
this.shooting = false;
},
aimBall: function(e){
// if the player is not shooting...
if(!this.shooting){
// the player is aiming
this.aiming = true;
}
},
adjustBall: function(e){
// if the player is aiming...
if(this.aiming){
// check distance between initial and current input position
var distX = e.position.x - e.positionDown.x;
var distY = e.position.y - e.positionDown.y;
// a vertical distance of at least 10 pixels is required
if(distY > 10){
// place the trajectory over the ball
this.trajectory.position.set(this.ball.x, this.ball.y);
// show trajectory
this.trajectory.visible = true;
// calculate direction
this.direction = Phaser.Math.angleBetween(e.position.x, e.position.y, e.positionDown.x, e.positionDown.y);
// adjust trajectory angle according to direction, in degrees
this.trajectory.angle = Phaser.Math.radToDeg(this.direction) + 90;
}
else{
// hide trajectory
this.trajectory.visible = false;
}
}
},
shootBall: function(){
// if the trajectory is visible...
if(this.trajectory.visible){
// get angle of fire in radians
var angleOfFire = Phaser.Math.degToRad(this.trajectory.angle - 90);
// set ball velocity
this.ball.body.velocity.set(gameOptions.ballSpeed * Math.cos(angleOfFire), gameOptions.ballSpeed * Math.sin(angleOfFire));
// the player is shooting!
this.shooting = true;
}
// do not aim anymore
this.aiming = false;
// do not show the trajectory anymore
this.trajectory.visible = false;
},
update: function(){
// if the player is shooting...
if(this.shooting){
// check for collision between the ball and the launch panel
game.physics.arcade.collide(this.ball, this.launchPanel, function(){
// stop the ball
this.ball.body.velocity.set(0);
// the player is not shooting
this.shooting = false;
}, null, this);
}
}
}
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