Canvas Sphere Animation Using HTML 5

Deepak Dwij
Mar 29, 2012
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Introduction

In this article we are going to understand canvas sphere animation using HTML 5. In this section you will see a 2D projection of the 3D points of a sphere using a a tiny sprite 3D engine when the application is running in the browser.

Here we will use some JavaScript and some styles along with HTML code. Just go through the steps to see how to create this application.

Let's see how the CanvasSphereApplication application can be created. To do so use the following steps.

Step 1 : Open a HTML editor or Visual Studio.

Open File menu ->select new ->Choose Website

This is where we will create the HTML5 application.

Go to Solution Explorer
Right-click on the Application name
Select Add-->add new item
Now in the window that opens, select an HTML page or new Web form
Rename it to sphereanimation.aspx

Step 2 : In this section we will create the style for the media and create the .css on the media screen. Put the given script in the Head section of the HTML or between the <head>--</head> tags. Here the CSS is used for design purposes.

CSS Script

<style>
body
{
    background-color: #1E90FF;
    margin: 0px;
    padding: 0px;
}
sphere
{
    background-color: #282828;
}
.title
{
   text-align: center;
   font-family: Segoe UI Light, Arial, Helvetica;
   font-size: 2.2em;
   margin: 1em;
}
.info
{
   text-align: center;
   font-family: Segoe UI Light, Arial, Helvetica;
   font-size: 1.2em;
   margin: 0.25em;
}
</style>

Step 3 : In this part we need to work with some JavaScript. To fully understand how JavaScript works, download the attached .rar file and run the CanvasSphereApplication application.

The JavaScript sphere.js looks as in the following:

Sphere = (function ()
{
    var canvas;
    var ctx;
    var offsetX = 300;
    var offsetY = 300;
    var objectsInScene = new Array();
    var focalLength = 300;
    var cameraView = { x: 0, y: 0, z: 0, rotX: 0, rotY: 0, rotZ: 0 };
    var space = 15;
    var PI = Math.PI;
    var radius = 200;
    var radian = PI / 180;
    var mouseX = 0;
    var mouseY = 0;
    var objectRadius = 14;
    var scaleRatio = 0;
    var scaling = true;
    var nrOfFollowers = 32;
    var followRadius = 8;
    var minDistToLeader = 20;
     return function ()
      {
        this.createSphere = function ()
        {
            canvas = document.getElementById("sphere");
            ctx = canvas.getContext("2d");
            if (canvas.getContext) {
                this.init();
            }
        }
        this.init = function () {
            // create sphere objects:
            for (var i = space; i < 180; i += space) {
                for (var angle = 0; angle < 360; angle += space) {
                    var object = {};
                    var x = Math.sin(radian * i) * radius;
                    object.x = Math.cos(angle * radian) * x;
                    object.y = Math.cos(radian * i) * radius;
                    object.z = Math.sin(angle * radian) * x;
                    object.glow = .5;
                    object.type = "sphere";
                    objectsInScene.push(object);
                }
            }
           // assign new leader when coming to close the current leader:
            if (distx < minDistToLeader && disty < minDistToLeader && distz < minDistToLeader) {
                 object.leader.glow = 1.0;
               this.assignLeader(object);
            }
        }
        this.createSphere();
    }
})();

Step 4 : In this section we are going to become familiar with the body part of HTML scripting. Replace this script from the body section of the sphereanimation.aspx page. Here we pass a Canvas in the canvas tag.

<body onload="new Sphere();">
<center>
<h1> Canvas Sphere In HTML 5 </h1>
<hr>
    <div align="center">
        <canvas id="sphere" width="600" height="580"></canvas>
    </div>
    </center>
</body>

Step 5 : The complete code for the CanvasSphereApplication application.

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="sphereanimation.aspx.cs" Inherits="CanvasSphereApplication._Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>Canvas sphere</title>
    <style>
    </style>
    <script language="JavaScript" src="sphere.js"></script>
    <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
    <style type="text/css">
    </style>
</head>
<body onload="new Sphere();">
<center>
<h1> Canvas Sphere In HTML 5 </h1>
<hr>
    <div align="center">
        <canvas id="sphere" width="600" height="580"></canvas>
    </div>
    </center>
</body>
</html>

Step 6 : Output Press F5

Note : For the accurate output of HTML5 applications, you must have the Google Chrome browser in your PC. You will see a 2D projection of the 3D points of a sphere using a tiny sprite 3D engine, while the application is running in the browser.

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