OpenGL. Shading Language. Third Edition

Transcription

1 OpenGL Shading Language Third Edition

2 OpenGL* Shading Language Third Edition Randi J. Rost Bill Licea-Kane With contributions by Dan Ginsburg, John M. Kessenich, Barthold Lichtenbelt, Hugh Malan, and Mike Weiblen r\addison-wesley T Upper Saddle River, NJ Boston Indianapolis San Francisco New York Toronto Montreal London Munich Paris Madrid Capetown Sydney Tokyo Singapore Mexico City

3 Contents Foreword to the Second Edition Foreword to the First Edition Preface About the Authors About the Contributors Acknowledgments xxi xxv xxix xxxv xxxvii xxxix Chapter 1. Review of OpenGL Basics OpenGL History OpenGL Evolution Execution Model The Framebuffer State Processing Pipeline Drawing Geometry Geometry Specification Per-Vertex Operations Primitive Assembly Primitive Processing Rasterization Fragment Processing Per-Fragment Operations Framebuffer Operations Drawing Images Pixel Unpacking 20 IX

4 Contents Pixel Transfer Rasterization and Back-End Processing Read Control Coordinate Transforms Texturing Summary Further Information 33 Chapter 2. Basics Introduction to the OpenGL Shading Language Why Write Shaders? OpenGL Programmable Processors Vertex Processor Fragment Processor Language Overview Language Design Considerations C Basis Additions to C Additions from C C Features Not Supported Other Differences System Overview Driver Model OpenGL Shading Language Compiler/Linker OpenGL Shading Language API Key Benefits Summary Further Information 63 Chapter 3. Language Definition Example Shader Pair Data Types Scalars Vectors Matrices Samplers Structures Arrays Void 75

5 Contents xi Declarations and Scope Type Matching and Promotion Initializers and Constructors Type Conversions Qualifiers and Interface to a Shader Uniform Qualifiers Uniform Blocks In Qualifiers (Vertex Shader) Out Qualifiers (Vertex Shader) In Qualifiers (Fragment Shader) Out Qualifiers (Fragment Shader) Constant Qualifiers Absent Qualifier Flow Control Functions Calling Conventions Built-in Functions Operations Indexing Swizzling Component-wise Operation Preprocessor Preprocessor Expressions Error Handling Summary Further Information 98 Chapter 4. The OpenGL Programmable Pipeline The Vertex Processor Vertex Attributes Special Input Variables Uniform Variables User-Defined Out Variables Special Output Variables The Fragment Processor User-Defined In Variables Special Input Variables Uniform Variables User-Defined Out Variables Special Output Variables 109

6 xii Contents 4.3 Built-in Uniform Variables Built-in Constants Interaction with OpenGL Fixed Functionality Ill Point Size Mode Ill Clipping Position Invariance Texturing Summary Further Information 115 Chapter 5. Built-in Functions Angle and Trigonometry Functions Exponential Functions Common Functions Geometric Functions Matrix Functions Vector Relational Functions Texture Access Functions Fragment Processing Functions Noise Functions Summary Further Information 178 Chapter 6. Simple Shading Example Brick Shader Overview Vertex Shader Fragment Shader Observations Summary Further Information 197 Chapter 7. OpenGL Shading Language API Obtaining Version Information Creating Shader Objects Compiling Shader Objects Linking and Using Shaders Cleaning Up Query Functions Specifying Vertex Attributes 217

7 Contents xiii 7.8 Specifying Uniform Variables Default Uniform Block Named Uniform Blocks Samplers Multiple Render Targets Development Aids Implementation-Dependent API Values Application Code for Brick Shaders Summary Further Information 248 Chapter 8. Shader Development General Principles Understand the Problem Add Complexity Progressively Test and Iterate Strive for Simplicity Exploit Modularity Performance Considerations Consider Computational Frequency Analyze Your Algorithm Use the Built-in Functions Use Vectors Use Textures to Encode Complex Functions Review the Information Logs Shader Debugging Use the Vertex Shader Output Use the Fragment Shader Output Use Simple Geometry Shader Development Tools RenderMonkey Apple GLSLEditorSample Graphic Remedy gdebugger OpenGL Shading Language Compiler Front End Scene Graphs Summary Further Information 266

8 xiv Contents Chapter 9. Emulating OpenGL Fixed Functionality Transformation Light Sources Directional Lights Point Lights Spotlights Material Properties and Lighting Two-Sided Lighting No Lighting Fog Texture Coordinate Generation User Clipping Texture Application Matrices Identity Matrix Scale Translate Rotate Ortho Frustum Operating on the Current Matrices A Simple Matrix Transformation Example Summary Further Information 294 Chapter 10. Stored Texture Shaders Access to Texture Maps from a Shader Simple Texturing Example Application Setup Vertex Shader Fragment Shader Multitexturing Example Application Setup Vertex Shader Fragment Shader Cube Mapping Example Application Setup Vertex Shader Fragment Shader 311

9 Contents XV 10.5 Another Environment Mapping Example Vertex Shader Fragment Shader Glyph Bombing Application Setup Vertex Shader Fragment Shader Summary Further Information 326 Chapter 11. Procedural Texture Shaders Regular Patterns Stripes Vertex Shader Stripes Fragment Shader Toy Ball Application Setup Vertex Shader Fragment Shader Lattice Bump Mapping Application Setup Vertex Shader Fragment Shader Normal Maps Summary Further Information 354 Chapter 12. Lighting Hemisphere Lighting Image-Based Lighting Lighting with Spherical Harmonics The Uberlight Shader Uberlight Controls Vertex Shader Fragment Shader Summary Further Information 376

10 xvi Contents Chapter 13. Shadows Ambient Occlusion Shadow Maps Application Setup Vertex Shader Fragment Shader Deferred Shading for Volume Shadows Shaders for First Pass Shaders for Second Pass Summary Further Information 400 Chapter 14. Surface Characteristics Refraction Diffraction BRDF Models Polynomial Texture Mapping with BRDF Data Application Setup Vertex Shader Fragment Shader Summary Further Information 432 Chapter 15. Noise Noise Defined D Noise Higher Dimensions of Noise Using Noise in OpenGL Shaders Noise Textures Trade-offs A Simple Noise Shader Application Setup Vertex Shader Fragment Shader Turbulence Sun Surface Shader Marble Granite 453

11 Contents xvii 15.7 Wood Application Setup Fragment Shader Summary Further Information 458 Chapter 16. Animation On/Off Threshold Translation Morphing Sphere Morph Vertex Shader Other Blending Effects Vertex Noise Particle Systems Application Setup Confetti Cannon Vertex Shader Further Enhancements Wobble Animating Once per Frame Application Setup Updating Matrices Once per Frame Summary Further Information 484 Chapter 17. Antialiasing Procedural Textures Sources of Aliasing Avoiding Aliasing Increasing Resolution Antialiased Stripe Example Generating Stripes Analytic Prefiltering Adaptive Analytic Prefiltering Analytic Integration Antialiased Brick Fragment Shader Frequency Clamping Antialiased Checkerboard Fragment Shader Summary Further Information 504

12 xviii Contents Chapter 18. Non-photorealistic Shaders Hatching Example Application Setup Vertex Shader Generating Hatching Strokes Obtaining Uniform Line Density Simulating Lighting Adding Character Hatching Fragment Shader Technical Illustration Example Application Setup Vertex Shader Fragment Shader Mandelbrot Example About the Mandelbrot Set Vertex Shader Fragment Shader Julia Sets Summary Further Information 530 Chapter 19. Shaders for Imaging Geometric Image Transforms Mathematical Mappings Lookup Table Operations Color Space Conversions Image Interpolation and Extrapolation Brightness Contrast Saturation Sharpness Blend Modes Normal Average Dissolve Behind Clear Darken Lighten 543

13 Contents xix Multiply Screen Color Burn Color Dodge Overlay Soft Light Hard Light Add Subtract Difference Inverse Difference Exclusion Opacity Convolution Smoothing Edge Detection Sharpening Summary Further Information 555 Chapter 20. Language Comparison Chronology of Shading Languages RenderMan OpenGL Shader (ISL) HLSL Cg Summary Further Information 570 Appendix A. Language Grammar 573 Appendix B. API Function Reference 589 Implementation-Dependent API Values for GLSL 590 Other Queriable Values for GLSL 591 glattachshader 592 glbindattriblocation 594 glcompileshader 597 glcreateprogram 599 glcreateshader 601 gldeleteprogram 603

14 XX Contents gldeleteshader 605 gldetachshader 607 gldrawbuffers 609 glenablevertexattribarray 612 glgetactiveattrib 614 glgetactiveuniform 617 glgetattachedshaders 621 glgetattriblocation 623 glgetprogram 625 glgetprogramlnfolog 628 glgetshader 630 glgetshaderlnfolog 632 glgetshadersource 634 glgetuniform 636 glgetuniformlocation 638 glgetvertexattrib 640 glgetvertexattribpointer 643 gllsprogram 645 gllsshader 647 gllinkprogram 648 glshadersource 652 gluniform 654 gluseprogram 661 glvalidateprogram 665 glvertexattrib 667 glvertexattribpointer 673 OpenGL 1.5 to OpenGL 2.0 GLSL Migration Guide 676 Afterword 681 Glossary 685 Further Reading 705 Index 721