Book Image

WebGL Beginner's Guide

Book Image

WebGL Beginner's Guide

Overview of this book

WebGL is a new web technology that brings hardware-accelerated 3D graphics to the browser without installing additional software. As WebGL is based on OpenGL and brings in a new concept of 3D graphics programming to web development, it may seem unfamiliar to even experienced Web developers.Packed with many examples, this book shows how WebGL can be easy to learn despite its unfriendly appearance. Each chapter addresses one of the important aspects of 3D graphics programming and presents different alternatives for its implementation. The topics are always associated with exercises that will allow the reader to put the concepts to the test in an immediate manner.WebGL Beginner's Guide presents a clear road map to learning WebGL. Each chapter starts with a summary of the learning goals for the chapter, followed by a detailed description of each topic. The book offers example-rich, up-to-date introductions to a wide range of essential WebGL topics, including drawing, color, texture, transformations, framebuffers, light, surfaces, geometry, and more. With each chapter, you will "level up"ù your 3D graphics programming skills. This book will become your trustworthy companion filled with the information required to develop cool-looking 3D web applications with WebGL and JavaScript.
Table of Contents (18 chapters)
WebGL Beginner's Guide
Credits
About the Authors
Acknowledgement
About the Reviewers
www.PacktPub.com
Preface
Index

Alpha blending


A fragment is eligible for alpha blending if it has passed the depth test. However, when depth testing is disabled, all fragments are eligible for alpha blending.

Alpha blending is enabled using the following line of code:

gl.enable(gl.BLEND);

For each eligible fragment the alpha blending operation reads the color present in the frame buffer for those fragment coordinates and creates a new color that is the result of a linear interpolation between the color previously calculated in the fragment shader (gl_FragColor) and the color already present in the frame buffer.

Note

Alpha blending is disabled by default in WebGL.

Blending function

With blending enabled, the next step is to define a blending function. This function will determine how the fragment colors coming from the object we are rendering (source) will be combined with the fragment colors already present in the frame buffer (destination).

We combine source and destination as follows:

Color Output = S * sW + D * dW

Here,

  • S: source...