Shader Writing in Open Shading Language

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