HTML5 Game Development - Lesson 7
Today we will create our first complete game – Arkanoid. In this lesson I
will show you how to detect basic collisions and work with HTML5 local
storage. You can operate using mouse and keyboard (left/right
buttons). We will store in local storage the elapsed time of previous games
and the amount of broken bricks (points).
Here you can read our previous lesson: Developing Your First HTML5 Game – Lesson 6.
Here are our demo and downloadable packages:
Live Demodownload in package
Ok, download the example files and lets start coding !
Step 1. HTML
Here is the source code of our seventh lesson:
index.html<!DOCTYPE html>
<html lang="en" >
<head>
<meta charset="utf-8" />
<title>HTML5 Game Development - Lesson 7 | Script Tutorials</title>
<link href="css/main.css" rel="stylesheet" type="text/css" />
<script src="js/jquery-1.5.2.min.js"></script>
<script src="js/script.js"></script>
</head>
<body>
<header>
<h2>HTML5 Game Development - Lesson 7</h2>
<a href="http://www.script-tutorials.com/html5-game-development-lesson-7/" class="stuts">Back to original tutorial on <span>Script Tutorials</span></a>
</header>
<div class="container">
<canvas id="scene" width="800" height="600"></canvas>
</div>
</body>
</html>
Step 2. CSS
Here are used CSS styles.
css/main.css/* page layout styles */
*{
margin:0;
padding:0;
}
body {
background-color:#eee;
color:#fff;
font:14px/1.3 Arial,sans-serif;
}
header {
background-color:#212121;
box-shadow: 0 -1px 2px #111111;
display:block;
height:70px;
position:relative;
width:100%;
z-index:100;
}
header h2{
font-size:22px;
font-weight:normal;
left:50%;
margin-left:-400px;
padding:22px 0;
position:absolute;
width:540px;
}
header a.stuts,a.stuts:visited{
border:none;
text-decoration:none;
color:#fcfcfc;
font-size:14px;
left:50%;
line-height:31px;
margin:23px 0 0 110px;
position:absolute;
top:0;
}
header .stuts span {
font-size:22px;
font-weight:bold;
margin-left:5px;
}
.container {
margin: 20px auto;
overflow: hidden;
position: relative;
width: 800px;
}
Step 3. JS
js/jquery-1.5.2.min.jsWe use jQuery for our lesson. Available in package. This file is the most important (here all our html5 functionality is located):
js/script.js// inner variables
var canvas, ctx;
var iStart = 0;
var bRightBut = false;
var bLeftBut = false;
var oBall, oPadd, oBricks;
var aSounds = [];
var iPoints = 0;
var iGameTimer;
var iElapsed = iMin = iSec = 0;
var sLastTime, sLastPoints;
// objects :
function Ball(x, y, dx, dy, r) {
this.x = x;
this.y = y;
this.dx = dx;
this.dy = dy;
this.r = r;
}
function Padd(x, w, h, img) {
this.x = x;
this.w = w;
this.h = h;
this.img = img;
}
function Bricks(w, h, r, c, p) {
this.w = w;
this.h = h;
this.r = r; // rows
this.c = c; // cols
this.p = p; // padd
this.objs;
this.colors = ['#9d9d9d', '#f80207', '#feff01', '#0072ff', '#fc01fc', '#03fe03']; // colors for rows
}
// -------------------------------------------------------------
// draw functions :
function clear() { // clear canvas function
ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height);
// fill background
ctx.fillStyle = '#111';
ctx.fillRect(0, 0, ctx.canvas.width, ctx.canvas.height);
}
function drawScene() { // main drawScene function
clear(); // clear canvas
// draw Ball (circle)
ctx.fillStyle = '#f66';
ctx.beginPath();
ctx.arc(oBall.x, oBall.y, oBall.r, 0, Math.PI * 2, true);
ctx.closePath();
ctx.fill();
if (bRightBut)
oPadd.x += 5;
else if (bLeftBut)
oPadd.x -= 5;
// draw Padd (rectangle)
ctx.drawImage(oPadd.img, oPadd.x, ctx.canvas.height - oPadd.h);
// draw bricks (from array of its objects)
for (i=0; i < oBricks.r; i++) {
ctx.fillStyle = oBricks.colors[i];
for (j=0; j < oBricks.c; j++) {
if (oBricks.objs[i][j] == 1) {
ctx.beginPath();
ctx.rect((j * (oBricks.w + oBricks.p)) + oBricks.p, (i * (oBricks.h + oBricks.p)) + oBricks.p, oBricks.w, oBricks.h);
ctx.closePath();
ctx.fill();
}
}
}
// collision detection
iRowH = oBricks.h + oBricks.p;
iRow = Math.floor(oBall.y / iRowH);
iCol = Math.floor(oBall.x / (oBricks.w + oBricks.p));
// mark brick as broken (empty) and reverse brick
if (oBall.y < oBricks.r * iRowH && iRow >= 0 && iCol >= 0 && oBricks.objs[iRow][iCol] == 1) {
oBricks.objs[iRow][iCol] = 0;
oBall.dy = -oBall.dy;
iPoints++;
aSounds[0].play(); // play sound
}
// reverse X position of ball
if (oBall.x + oBall.dx + oBall.r > ctx.canvas.width || oBall.x + oBall.dx - oBall.r < 0) {
oBall.dx = -oBall.dx;
}
if (oBall.y + oBall.dy - oBall.r < 0) {
oBall.dy = -oBall.dy;
} else if (oBall.y + oBall.dy + oBall.r > ctx.canvas.height - oPadd.h) {
if (oBall.x > oPadd.x && oBall.x < oPadd.x + oPadd.w) {
oBall.dx = 10 * ((oBall.x-(oPadd.x+oPadd.w/2))/oPadd.w);
oBall.dy = -oBall.dy;
aSounds[2].play(); // play sound
}
else if (oBall.y + oBall.dy + oBall.r > ctx.canvas.height) {
clearInterval(iStart);
clearInterval(iGameTimer);
// HTML5 Local storage - save values
localStorage.setItem('last-time', iMin + ':' + iSec);
localStorage.setItem('last-points', iPoints);
aSounds[1].play(); // play sound
}
}
oBall.x += oBall.dx;
oBall.y += oBall.dy;
ctx.font = '16px Verdana';
ctx.fillStyle = '#fff';
iMin = Math.floor(iElapsed / 60);
iSec = iElapsed % 60;
if (iMin < 10) iMin = "0" + iMin;
if (iSec < 10) iSec = "0" + iSec;
ctx.fillText('Time: ' + iMin + ':' + iSec, 600, 520);
ctx.fillText('Points: ' + iPoints, 600, 550);
if (sLastTime != null && sLastPoints != null) {
ctx.fillText('Last Time: ' + sLastTime, 600, 460);
ctx.fillText('Last Points: ' + sLastPoints, 600, 490);
}
}
// initialization
$(function(){
canvas = document.getElementById('scene');
ctx = canvas.getContext('2d');
var width = canvas.width;
var height = canvas.height;
var padImg = new Image();
padImg.src="images/padd.png";
padImg.onload = function() {};
oBall = new Ball(width / 2, 550, 0.5, -5, 10); // new ball object
oPadd = new Padd(width / 2, 120, 20, padImg); // new padd object
oBricks = new Bricks((width / <img src="http://www.script-tutorials.com/wp-includes/images/smilies/icon_cool.gif" alt="8)" class="wp-smiley"> - 1, 20, 6, 8, 2); // new bricks object
oBricks.objs = new Array(oBricks.r); // fill-in bricks
for (i=0; i < oBricks.r; i++) {
oBricks.objs[i] = new Array(oBricks.c);
for (j=0; j < oBricks.c; j++) {
oBricks.objs[i][j] = 1;
}
}
aSounds[0] = new Audio('media/snd1.wav');
aSounds[0].volume = 0.9;
aSounds[1] = new Audio('media/snd2.wav');
aSounds[1].volume = 0.9;
aSounds[2] = new Audio('media/snd3.wav');
aSounds[2].volume = 0.9;
iStart = setInterval(drawScene, 10); // loop drawScene
iGameTimer = setInterval(countTimer, 1000); // inner game timer
// HTML5 Local storage - get values
sLastTime = localStorage.getItem('last-time');
sLastPoints = localStorage.getItem('last-points');
$(window).keydown(function(event){ // keyboard-down alerts
switch (event.keyCode) {
case 37: // 'Left' key
bLeftBut = true;
break;
case 39: // 'Right' key
bRightBut = true;
break;
}
});
$(window).keyup(function(event){ // keyboard-up alerts
switch (event.keyCode) {
case 37: // 'Left' key
bLeftBut = false;
break;
case 39: // 'Right' key
bRightBut = false;
break;
}
});
var iCanvX1 = $(canvas).offset().left;
var iCanvX2 = iCanvX1 + width;
$('#scene').mousemove(function(e) { // binding mousemove event
if (e.pageX > iCanvX1 && e.pageX < iCanvX2) {
oPadd.x = Math.max(e.pageX - iCanvX1 - (oPadd.w/2), 0);
oPadd.x = Math.min(ctx.canvas.width - oPadd.w, oPadd.x);
}
});
});
function countTimer() {
iElapsed++;
}
I added my comments anywhere, hope that all code is pretty understandable. Please pay attention to ‘localStorage’ object to understand how to work with HTML5 Local storage (I use ‘setItem’ method to store something and ‘getItem’ to read this from local storage). Also, it can be also interesting to understand how to calculate collisions between the ball and bricks.
Live Demodownload in package
Conclusion
Today, we made our first arkanoid game. Most functionality are already here. We have implemented our first knowledge about collisions and HTML5 local storage too. I will be glad to see your thanks and comments. Good luck!
Source: http://www.script-tutorials.com/html5-game-development-lesson-7/
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