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

Drawing triangles


There is no direct function to draw a triangle using the canvas API. But we do have the other, simpler functions that, together, allow us to draw different shapes. A triangle is a combination of three joined lines. Let's see this in our new example. The output is quite simple and looks like this:

How to do it…

The triangle is drawn by calling two basic functions, namely moveTo() and lineTo(). Here is the recipe.

The HTML file:

<html>
<head>
<title>triangles</title>
<script src="triangles.js"></script>
</head>
<body onload="init()">
<canvas id="MyCanvasArea" width="200" height="200" style="border:2px solid blue;" >
      your browser does not support canvas
</canvas>
<H1>Triangle</H1>
</body>
</html>

The JavaScript file:

function init(){
  var can = document.getElementById("MyCanvasArea");
  if(can.getContext)
  {
    var context=can.getContext("2d");  
    drawTriangle(context,100,20,100,100,...