Incorporating both historical techniques and the most recent developments in computer graphics, Shader Writing in Open Shading Language is a treatise on OSL shader writing and shader development that intends to remedy the current lack of material on this important area of technical and artistic expertise. It is for artists who wish to know more about shaders and shader writing, for programmers who want the ultimate in creative control, or for anyone in-between. It begins by covering the entire range of independent variables upon which all shaded pattern generation is based. From that foundation, every fundamental procedural, textural, conversion, and pattern modification shader category is described with clear and practical examples. Each topic is presented in a progression of chapters that begin with the fundamentals and expand to more complex shaders illustrating more advanced techniques that build on the previously covered material. In addition, these important topics are also covered: Shader user interface design and parameter widgets Color, color models, color spaces, and color transformations 2d and 3d spaces and their transformations Texture patterns and projections Ray tracing for pattern generation Displacement and bumped shading normal generation Shader organization, building, and deployment Shader execution and debugging

Table of Contents:
Preface 1. Introduction 2. Variables 2.1 Data Types 2.2 Compound Types 2.2.1 Arrays 2.2.2 Structs 2.3 Global 2.4 Built In 2.5 Primitive 2.5.1 Parameter Access 2.5.2 getattribute() Access 2.6 Options and Attributes 2.6.1 OSL Attributes 2.6.2 RenderMan Options and Attributes 2.6.3 User Attributes 2.7 Example Shaders 2.7.1 Global Variables 2.7.2 Built In Variables 2.7.3 Primitive Variables 3. Coordinate Systems 4. Conversion Shaders 4.1 Simple Types 4.1.1 Float to Color 4.1.2 Color to Float 4.1.3 Type Connections 4.2 Artistic to Physical 4.2.1 Base Color and Metallic to Specular Face and Edge Colors 4.2.2 Specular Face and Edge Colors to Complex Refractive Index 5. Color 5.1 Color Models 5.1.1 RGB 5.1.2 HSV & HSL 5.1.3 CMYK 5.1.4 Spectral 5.2 Color Spaces 5.2.1 CIE 1931 XYZ 5.2.2 xyY 5.2.3 Television Standards 5.2.4 Web Standard 5.2.5 Academy Standards 5.3 Color Space Conversions 5.3.1 sRGB to Rec. 709 5.3.2 Rec. 709 to ACEScg 5.3.2 sRGB to ACEScg 6. Spaces and Transformations 5.1 2D Space 5.2 3D Space 5.3 2D Transform 5.2 3D Transform 7. Texture Patterns 7.1 File Names 7.1.1 String Functions 7.1.2 Tokens 7.2 t Inversion 7.3 Metadata 7.4 Data Access 7.5 Projections 7.5.1 Orthographic 7.5.2 Shear 7.5.3 Spherical 7.5.4 NDC 7.5.5 Rounded Cube 8. Procedural Patterns 8.1 Spatial Conversion 8.1.1 Float and Gray Outputs 8.2 Noise 8.3 Cellular 8.3.1 Tessellation 8.3.2 Worley 8.4 Spatial Warping 8.5 Fractals 8.5.1 Distortion 8.6 Ray Tracing 9. Signal Modification 9.1 Contrast 9.1.1 Average Value Interpolation 9.1.2 Range Remapping 9.1.3 Redistribution 9.2 Creasing 9.3 Skew 9.4 Range Clamping 9.5 Combining 9.5.1 Binary Operators 9.5.2 Weighted Mixing 9.5.3 Layering 9.5.4 Patterned Transitions 10. Displacement and Bumping 10.1 Common Space 10.2 Displacement 10.2.1 Height Patterns 10.2.2 Vector Patterns 10.2.3 Cascading Height Displacements 10.2.4 Geometry Inversion 10.3 Bumping 10.3.1 Vertex Shading Normals 10.3.2 BxDF Normal Orientation 10.3.3 Bump Conversion Shader 11. Shader Execution 11.1 JIT Optimization 11.2 Strings and Filenames 11.3 Displacement and BxDF Shading Phases 11.3.1 Micropolygon Dicing 11.3.2 Common Space 11.3.3 Surface Variables 11.3.4 "Original" Surface Variables 11.3.5 Ray Tracing 11.4 Differentiation 12. Interface Design 12.1 Naming 12.2 Metadata 12.3 Widgets 12.4 Types and Connections 12.5 Help Content 13. Development, Deployment, and Debugging 13.1 Source File Organization 13.2 Build System 13.3 Debugging 13.3.1 IT 13.3.2 printf() 13.3.3 The .rib File Appendix A. Pattern Dimension and the Fourier Slice Theorem B. Fractal Dimension C. Arbitrary Output Variables D. Light Path Expressions E. Build System i. Top-level Makefile ii. osl Makefile iii. install_shaders.py