OpenGL ES 2.0 Programming Guide

Product Author Bios

Aaftab Munshi is the spec editor for the OpenGL ES 1.1 and 2.0 specifications. Now at Apple, he was formerly senior architect in ATI’s handheld group.

Dan Ginsburg is senior member of technical staff at AMD. At AMD and ATI, he has worked in a variety of roles, including the development of OpenGL drivers, the creation of desktop and handheld 3D demos, and the development of handheld GPU developer tools.

Dave Shreiner is one of the world’s foremost authorities on OpenGL. He is a systems architect at ARM, Inc., and the lead author of the official OpenGL® Programming Guide, Sixth Edition (Addison-Wesley, 2007) and series editor for the Addison-Wesley OpenGL Series.

OpenGL ES 2.0 is the industry’s leading software interface and graphics library for rendering sophisticated 3D graphics on handheld and embedded devices. With OpenGL ES 2.0, the full programmability of shaders is now available on small and portable devices—including cell phones, PDAs, consoles, appliances, and vehicles. However, OpenGL ES differs significantly from OpenGL. Graphics programmers and mobile developers have had very little information about it—until now.

In the OpenGL® ES 2.0 Programming Guide, three leading authorities on the Open GL ES 2.0 interface—including the specification’s editor—provide start-to-finish guidance for maximizing the interface’s value in a wide range of high-performance applications. The authors cover the entire API, including Khronos-ratified extensions. Using detailed C-based code examples, they demonstrate how to set up and program every aspect of the graphics pipeline. You’ll move from introductory techniques all the way to advanced per-pixel lighting, particle systems, and performance optimization. 

Coverage includes:

• Shaders in depth: creating shader objects, compiling shaders, checking for compile errors, attaching shader objects to program objects, and linking final program objects
• The OpenGL ES Shading Language: variables, types, constructors, structures, arrays, attributes, uniforms, varyings, precision qualifiers, and invariance
• Inputting geometry into the graphics pipeline, and assembling geometry into primitives
• Vertex shaders, their special variables, and their use in per-vertex lighting, skinning, and other applications
• Using fragment shaders—including examples of multitexturing, fog, alpha test, and user clip planes
• Fragment operations: scissor test, stencil test, depth test, multisampling, blending, and dithering
• Advanced rendering: per-pixel lighting with normal maps, environment mapping, particle systems, image post-processing, and projective texturing
• Real-world programming challenges: platform diversity, C++ portability, OpenKODE, and platform-specific shader binaries

Online Sample Chapter

Hello Triangle: An OpenGL ES 2.0 Example

Table of Contents

List of Figures                  xiii
List of Examples                xv
List of Tables                    xix
Foreword                           xxi
Preface                            xxiii
Acknowledgments          xxix
About the Authors          xxxi

Chapter 1. Introduction to OpenGL ES 2.0                       1
What Is OpenGL ES?                     1
OpenGL ES 2.0                              3
Vertex Shader                                 4
Primitive Assembly                       6
Rasterization                                 7
Fragment Shader                             7
Per-Fragment Operations                9
OpenGL ES 2.0 and OpenGL ES 1.x Backward Compatibility           11
EGL                       12
Programming with OpenGL ES 2.0                    13
Further Reading                          18

Chapter 2. Hello Triangle: An OpenGL ES 2.0 Example                    19
Code Framework                      20
Where to Download the Examples                    20
Hello Triangle Example                       21
Building and Running the Examples                       25
Using the OpenGL ES 2.0 Framework                      26
Creating a Simple Vertex and Fragment Shader                    27
Compiling and Loading the Shaders                    29
Creating a Program Object and Linking the Shaders                 30
Setting the Viewport and Clearing the Color Buffer                   32
Loading the Geometry and Drawing a Primitive                   33
Displaying the Back Buffer                   33

Chapter 3. An Introduction to EGL                         35
Communicating with the Windowing System               36
Checking for Errors                   37
Initializing EGL                   37
Determining the Available Surface Configurations                 38
Querying EGLConfig Attributes                    39
Letting EGL Choose the Config                     39
Creating an On-Screen Rendering Area: The EGL Window                43
Creating an Off-Screen Rendering Area: EGL Pbuffers                  46
Creating a Rendering Context                     50
Making an EGLContext Current                        52
Putting All Our EGL Knowledge Together                       52
Synchronizing Rendering                       54

Chapter 4. Shaders and Programs                     57
Shaders and Programs                      57
Uniforms and Attributes                    67
Shader Compiler and Shader Binaries                     72

Chapter 5. OpenGL ES Shading Language                   77
OpenGL ES Shading Language Basics                     78
Variables and Variable Types                    78
Variable Constructors                   79
Vector and Matrix Components                  81
Constants                   82
Structures                     82
Arrays                    83
Operators                     84
Functions                        85
Built-In Functions                      86
Control Flow Statements                 87
Uniforms                    88
Attributes                89
Varyings                    90
Preprocessor and Directives                 92
Uniform and Varying Packing                 94
Precision Qualifiers                     96
Invariance                     97

Chapter 6. Vertex Attributes, Vertex Arrays, and Buffer Objects                101
Specifying Vertex Attribute Data                  102
Declaring Vertex Attribute Variables in a Vertex Shader               110
Vertex Buffer Objects                 115
Mapping Buffer Objects                   124

Chapter 7. Primitive Assembly and Rasterization                 127
Primitives                     127
Drawing Primitives                  131
Primitive Assembly                   136
Rasterization                 141

Chapter 8. Vertex Shaders                   147
Vertex Shader Overview                 148
Vertex Shader Examples                 159
Generating Texture Coordinates                167
Vertex Skinning             168
OpenGL ES 1.1 Vertex Pipeline as an ES 2.0 Vertex Shader            173

Chapter 9. Texturing                 181
Texturing Basics                181
Compressed Textures            201
Texture Subimage Specification               202
Copying Texture Data from the Color Buffer               204
Optional Extensions               207

Chapter 10. Fragment Shaders              215
Fixed Function Fragment Shaders              216
Fragment Shader Overview                218
Implementing Fixed Function Techniques Using Shaders            222

Chapter 11. Fragment Operations                233
Buffers                234
Fragment Tests and Operations                238
Blending                246
Dithering               249
Multisampled Antialiasing                249
Reading and Writing Pixels to the Framebuffer                  250

Chapter 12. Framebuffer Objects                   253
Why Framebuffer Objects                   253
Framebuffer and Renderbuffer Objects                 255
Creating Framebuffer and Renderbuffer Objects               258
Using Renderbuffer Objects                   259
Using Framebuffer Objects                     262
Deleting Framebuffer and Renderbuffer Objects               269
Examples                    271
Performance Tips and Tricks                 277

Chapter 13. Advanced Programming with OpenGL ES 2.0                279
Per-Fragment Lighting                279
Environment Mapping                  286
Particle System with Point Sprites               290
Image Postprocessing                  296
Projective Texturing                   300
Noise Using a 3D Texture              307
Procedural Texturing                 315

Chapter 14. State Queries                 323
OpenGL ES 2.0 Implementation String Queries              323
Querying Implementation-Dependent Limits                 324
Querying OpenGL ES State             327
Hints               330
Entity Name Queries             331
Nonprogrammable Operations Control and Queries               332
Shader and Program State Queries               333
Vertex Attribute Queries               335
Texture State Queries              336
Vertex Buffer Queries                337
Renderbuffer and Framebuffer State Queries              337

Chapter 15. OpenGL ES and EGL on Handheld Platforms              339
Handheld Platforms Overview              339
C++ Portability                341
OpenKODE                  343
Platform-Specific Shader Binaries                 350
Targeting Extensions                  351

Appendix A. GL_HALF_FLOAT_OES                    353
16-Bit Floating-Point Number                     354
Converting Float to Half-Float                   355

Appendix B. Built-In Functions                    357
Angle and Trigonometry Functions                358
Exponential Functions                     360
Common Functions                     361
Geometric Functions                      364
Matrix Functions                     366
Vector Relational Functions                 367
Texture Lookup Functions                 369
Derivative Functions                 371

Appendix C. Shading Language Grammar                 375

Appendix D. ES Framework API                     385
Framework Core Functions                   385
Transformation Functions                     390

Index                       395

Sample Pages

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