Thursday, January 22, 2015

Using HTML5 canvas to create a simple game.

Here  a simple game is made using HTML5 , follow the steps to create the application.
The HTML page is used to create the canvas, the coding for the HTML page is given below


The above screen shot shows the canvas created using HTML





<html>
    <head>
        <title>HTML5 Avoider Game</title>
        <script src="js/main.js"></script>
        <link rel="stylesheet" href="css/style.css" />
    </head>
    <body>
<canvas id="gameCanvas" onclick="drawAvatar();" width="400" height="300"></canvas>
        <p>From <a href="http://codemonkeyy.blogspot.com" rel="external">Learn to code @ "CODEMONKEYY"</a>.</p>
    </body>
</html>

CSS is used to change the size of the canvas and to make the cursor disappear.The CSS coding is provided below


body {
    background: #ffffff;  
    text-align: center; 
    padding: 20px; 
    color: #575757; 
    font: 14px/21px Arial,Helvetica,sans-serif;
}

a {
    color: #B93F14;
}

a:hover {
    text-decoration: none;
}

ol {
    width: 600px; 
    text-align: left; 
    margin: 15px auto
}
canvas {
    border: 1px solid black;
    cursor: none;// Remove the cursor
}

Java script is used to create duplicate images and to move the image around the canvas with the cursor. The java script coding is provided below


function alertSeveralTimes() {
    alert("Hello!");
    alert("Welcome to codemonkeyy.");
    alert("wanna code?");

}
function changeCanvasSize() {
    var gameCanvas = document.getElementById("gameCanvas");
    var avatarImage = new Image();
         
    gameCanvas.width = 600;
    gameCanvas.height = 800;
     
    avatarImage.src = "img/avatar.png";
gameCanvas.getContext("2d").drawImage(avatarImage, Math.random() * 100, Math.random() * 100);
}
function drawAvatar() {
    var gameCanvas = document.getElementById("gameCanvas");
    var avatarImage = new Image();
     
    avatarImage.src = "img/avatar.png";
    gameCanvas.getContext("2d").drawImage(avatarImage, Math.random() * 100, Math.random() * 100);
     
    gameCanvas.addEventListener("mousemove", redrawAvatar);
}

function redrawAvatar(mouseEvent) {
    var gameCanvas = document.getElementById("gameCanvas");
    var avatarImage = new Image();
    var enemyImage = new Image();
     
    avatarImage.src = "img/avatar.png";
    enemyImage.src = "img/enemy.png";
    gameCanvas.width = 400;     //this erases the contents of the canvas
    gameCanvas.getContext("2d").drawImage(avatarImage, mouseEvent.offsetX, mouseEvent.offsetY);
    gameCanvas.getContext("2d").drawImage(enemyImage, 250, 150);
     
    if (mouseEvent.offsetX > 150 && mouseEvent.offsetX < 250 && mouseEvent.offsetY > 100 && mouseEvent.offsetY < 200) {
        alert("You hit the monkey!");
    }
}


The screen shot below shows the simple game developed using HTML5, try it for your self.


Use these two images for the avatars in the game


HAVE FUN



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