Shader Writing in Open Shading Language: With RenderMan® Examples

by Mitch J. Prater

Overview

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

Product Details

ISBN-13:	9781032421100
Publisher:	CRC Press
Publication date:	10/03/2024
Pages:	238
Product dimensions:	7.00(w) x 10.00(h) x (d)

About the Author

Mitch Prater's interest in graphics began at age 12 when he set out to build his own "Pong" game based on an article in Popular Electronics magazine. Mitch graduated from hardware to software implementations with Fortran IV programmed on punch cards and a line-printer for output. Through the 1980's and 1990's he progressed through CRT terminals, dedicated graphics hardware, integrated GPU chips, graphics libraries, and finally into rendering systems with dedicated shading languages when in 1988 he began working at Pixar using the Pixar Image Computer and was introduced to the 1.0 alpha version of RenderMan. From there Mitch wrote shaders and created new shading and lighting techniques for use in Pixar's commercials, short films, and all the features from Toy Story to Cars; and then again from ParaNorman to Missing Link at Laika. Throughout a career that now spans nearly 40 years, Mitch Prater continuously developed new shading and lighting techniques, shader code libraries, and production shaders for feature films, animated shorts, and real-time games.

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