Book Image

Canvas Cookbook

Book Image

Canvas Cookbook

Overview of this book

With the growing popularity of HTML5 Canvas, this book offers tailored recipes to help you develop portable applications, presentations, and games. The recipes are simple yet creative and build on each other. At every step, the book inspires the reader to develop his/her own recipe. From basic to advanced, every aspect of Canvas API has been covered to guide readers to develop their own application, presentation, or game.
Table of Contents (16 chapters)
Canvas Cookbook
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

Demonstrating gravity


Gravity can be understood as acceleration along the y axis, otherwise known as things falling straight to the ground. The output of this recipe is shown as follows:

How to do it…

This recipe is similar to the previous one. The recipe is as follows.

The HTML code:

<html>
<head>
<title>Demonstration of Gravity</title>
<script src="Gravity.js"></script>
</head>
<body onload="init();">
<canvas id="MyCanvasArea" width="200" height="600" style="border:2px solid blue;" >
   your browser does not support canvas
</canvas>
<h1>Demonstration of Gravity</h1>
</body>
</html>

The JavaScript code:

var x =  0;
var y = 80;
var yEnd=600;
var goDown=true;
//same as prior recipe
....
....
function animate() {
//same as prior recipe
....
....
}
function updateLine()
{
    if(y<yEnd && goDown)
    {
      y=acceleration*time*time;
      time+=2;
    } 
    if(y>=yEnd)
    {
      goDown=false;
  ...