"Cg is the key to unlocking the power of a new generation of programmable graphics hardware. This book is the definitive introduction to Cg, and will be essential for anyone programming high-quality real-time graphics. The Cg Tutorial will teach you to use Cg to create effects never before available for real-time applications."
--Larry Gritz, Author of Advanced RenderMan (Morgan Kaufmann, 2000)
"An important and timely book: Pixel-level procedural textures--animated clouds, fire, water, the whole bag of procedural tricks--finally go from the movie screen to the desktop. Access to computation of this power through a C-like language will usher in an exciting new era for the graphics community."
--Ken Perlin, Professor, New York University
Cg (C for graphics) is a complete programming environment for the fast creation of special effects and real-time cinematic quality experiences on multiple platforms. By providing a new level of abstraction, Cg lets developers more directly target OpenGL®, DirectX®, Windows®, Linux, Mac OS X®, and console platforms, such as the Xbox™, without having to program directly to the graphics hardware assembly language. Cg was developed by NVIDIA® Corporation in close collaboration with Microsoft® Corporation, and is compatible with both the OpenGL API and Microsoft's HLSL for DirectX 9.0.
The Cg Tutorial explains how to implement both basic and advanced techniques for today's programmable GPU architectures.
Major topics covered include:
The accompanying CD-ROM includes the tools needed to run the sample programs in the book.
The Cg Tutorial: The Definitive Guide to Programmable Real-Time Graphics Supplements
Click below for Sample Chapter(s) related to this title:
Sample Chapter 7
Figures and Plates.
What Is Cg?
A Language for Programming Graphics Hardware.
Cg's Data-Flow Model.
GPU Specialization and CPU Generalization.
The Performance Rationale for Cg.
Coexistence with Conventional Languages.
Other Aspects of Cg.
The Limited Execution Environment of Cg Programs.
Vertices, Fragments, and the Graphics Pipeline.
The Evolution of Computer Graphics Hardware.
Four Generations of Computer Graphics Hardware.
The Graphics Hardware Pipeline.
The Programmable Graphics Pipeline.
Cg Provides Vertex and Fragment Programmability.
Cg's Historical Development.
Microsoft and NVIDIA's Collaboration to Develop Cg and HLSL.
Noninteractive Shading Languages.
Programming Interfaces for 3D Graphics.
The Cg Environment.
Standard 3D Programming Interfaces: OpenGL and Direct3D.
The Cg Compiler and Runtime.
The CgFX Toolkit and File Format.
A Simple Vertex Program.
Input and Output Semantics Are Different.
The Function Body.
Compiling Your Example.
Vertex Program Profiles.
Classes of Cg Compilation Errors.
The Norm: Multiple Entry Functions.
Downloading and Configuring Vertex and Fragment Programs.
A Simple Fragment Program.
Fragment Program Profiles.
Rendering with Your Vertex and Fragment Program Examples.
Rendering a Triangle with OpenGL.
Rendering a Triangle with Direct3D.
Getting the Same Results.
The const Type Qualifier.
Sending Texture Coordinates While Sampling a Texture.
Profile-Dependent Numeric Data Types.
Standard Library Built-In Functions.
The Modeling Transform.
The View Transform.
The Projection Transform.
Normalized Device Coordinates.
Applying the Theory
Lighting and Lighting Models.
Implementing the Basic Per-Vertex Lighting Model.
The Basic Lighting Model.
A Vertex Program for Basic Per-Vertex Lighting.
The Fragment Program for Per-Vertex Lighting.
Per-Vertex Lighting Results.
Implementing Per-Fragment Lighting.
The Vertex Program for Per-Fragment Lighting.
The Fragment Program for Per-Fragment Lighting.
Creating a Lighting Function.
Declaring a Function.
A Lighting Function
Computing the Diffuse and Specular Lighting.
Extending the Basic Model.
Adding a Spotlight Effect.
Movement in Time.
A Pulsating Object.
The Vertex Program.
The Particle System Parameters.
The Vertex Program.
Dressing Up Your Particle System.
Basic Key-Frame Interpolation.
Key-Frame Interpolation with Lighting.
The Theory of Vertex Skinning.
Vertex Skinning in a Vertex Program.
Cube Map Textures.
Generating Cube Maps.
The Environment Mapping Concept.
Computing Reflection Vectors.
Assumptions for Environment Mapping.
Reflective Environment Mapping.
The Vertex Program.
The Fragment Program.
Vertex Program vs. Fragment Program.
Refractive Environment Mapping.
The Physics of Refraction.
The Vertex Program.
The Fragment Program.
The Fresnel Effect and Chromatic Dispersion.
The Fresnel Effect.
The Vertex Program.
The Fragment Program.
Bump Mapping a Brick Wall.
The Brick Wall Normal Map.
Storing Bump Maps As Normal Map Textures.
Simple Bump Mapping for a Brick Wall.
Specular Bump Mapping.
Bump Mapping Other Geometry.
Bump Mapping a Brick Floor.
The Vertex Program for Rendering a Brick Floor.
Bump Mapping a Torus.
The Mathematics of the Torus.
The Bump-Mapped Torus Vertex Program.
Bump Mapping Textured Polygonal Meshes.
Examining a Single Triangle.
Generalizing to a Polygonal Mesh.
Combining Bump Mapping with Other Effects.
The Attributes of Fog.
The Mathematics of Fog.
Intuiting the Equations.
Creating Uniform Fog with Cg.
Implementing Toon Shading.
Putting It All Together.
Problems with This Technique.
How Projective Texturing Works.
Implementing Projective Texturing.
The Code for Projective Texturing.
Mapping Input to Output Pixels.
Basic Compositing Operations.
The Vertex Shader Profile for DirectX 8.
The Basic NVIDIA Vertex Program Profile for OpenGL.
The ARB Vertex Program Profile for OpenGL.
The Vertex Shader Profiles for DirectX 9.
The Advanced NVIDIA Vertex Program Profile for OpenGL.
The Pixel Shader Profiles for DirectX 8.
The Basic NVIDIA Fragment Program Profile for OpenGL.
The DirectX 9 Pixel Shader Profiles.
The ARB Fragment Program Profile for OpenGL.
The Advanced NVIDIA Fragment Program Profile for OpenGL.
Use the Cg Standard Library.
Take Advantage of Uniform Parameters.
Using Vertex Programs vs. Fragment Programs.
Data Types and Their Impact on Performance.
Take Advantage of Vectorization.
Use Textures to Encode Functions.
Use Swizzling and Negation Freely.
Shade Only the Pixels That You Must.
Shorter Assembly Is Not Necessarily Faster.
Getting This Book's Accompanying Software.
Getting the Cg Toolkit.
What Is the Cg Runtime?
Why Use the Cg Runtime?
No Dependency Issues.
Input Parameter Management.
How Does the Cg Runtime Work?.
Creating a Context.
Compiling a Program.
Loading a Program.
Modifying the Program Parameters.
Executing a Program.
What Is CgFX?
Variables and Semantics.
A Sample CgFX File.
Cg Plug-Ins Supporting the CgFX Format.
Learning More About CgFX.
Cg Keyword List.
Texture Map Functions.
Once upon a time, real-time computer graphics was all about vertices, triangles, and pixels. In fact, it still is. However, the level at which a programmer controls the processing and appearance of these graphics primitives has advanced considerably. It once was the case (even as of a few years ago) that a programmer had to implement all the transformation and rasterization algorithms needed to generate computer-generated images completely with the CPU. Over time, hardware engineers implemented these algorithms via specialized, high-performance 3D graphics hardware. Rather than implement the algorithms directly, programmers learned to access the hardware-provided graphics functionality through standard 3D programming interfaces such as SGI's OpenGL. At first, only high-priced UNIX workstations and flight simulators benefited from specialized 3D graphics hardware because of the cost, but through the miracle of Moore's Law the benefits of graphics hardware acceleration have been transferred to low-cost PCs and game consoles.
While the performance gained by turning over the brute force tasks of transforming vertices, rasterizing triangles, and updating pixels to dedicated graphics hardware far exceeded the performance possible just with CPU programming, real-time 3D programmers gave up a considerable measure of control for this speed. Developers were limited to using a fixed-function palette of graphics operations that the hardware could handle. Sometimes a skilled and dedicated programmer could coax the graphics programming interface and hardware to accomplish something beyond the ordinary, but this was usually hard, time-consuming work.
While graphics hardware engineers were advancing the real-time performance of their specialized pixel-pushing hardware, off-line computer graphics software packages such as Pixar's Photorealistic RenderMan were changing the look of movies and television with amazing computer-generated special effects. The pre-recorded nature of movies and most television content makes these media well suited for off-line rendering. Computer-generated images for film and video are not rendered in real-time but instead carefully constructed frame by frame in hours, days, or weeks using standard general-purpose CPUs. The advantage of using general-purpose CPUs is that rather than settling for hard-wired hardware algorithms, CPUs can be programmed for any effect that a programmer or artist might imagine. What these so-called off-line rendering systems lack in relative speed, they make up in rendering quality and realism.
The flexibility and generality of these off-line rendering systems is what has been missing from preceding generations of 3D graphics hardware. The missing ingredient is programmability.
Realizing this, computer graphics architects have designed a new generation of graphics hardware that permits an unprecedented degree of programmability so that many of the programmable shading techniques from off-line rendering can be transferred into the realm of real-time graphics.
Off-line rendering systems developed a type of specialized computer language known as a shading language to express the graphics operations required to make a surface appear how an artist intends the surface to appear. A shading language for programmable graphics hardware provides the same sort of functionality but in the context of real-time graphics hardware. Graphics programmers and artists benefit from such a high-level programming language in much the same way conventional programmers benefit from high-level languages such as C++ or Java. Using a shading language for graphics hardware automates the process of translating the programmer's intent into a form that the graphics hardware can execute.
This book is about Cg, the premier language for programmable graphics hardware. NVIDIA developed Cg in close collaboration with Microsoft. Cg is the most portable and productive way for you to unleash the power within programmable graphics hardware. This book is a tutorial to teach you how to write Cg programs.
We tried to write this book in a way that makes it valuable to both novices and advanced readers. If youre new to the world of programmable graphics, this book should give you a firm foundation on which to build. If you encounter a word or concept that is foreign to you and not sufficiently explained, consult the glossary or the Further Reading section at the end of each chapter.
The main audience for this book is 3D game and application programmers, managers of such projects, real-time 3D artists, and computer graphics students--or anyone else interested in learning about the state-of-the-art in real-time rendering. You do not have to be an experienced programmer to learn Cg from this book though you should be relatively familiar with programming language concepts. If you are familiar with C or one of its derivatives, such as C++ or Java, Cg will be very approachable. Cg programs are relatively short, often less than a page, so even an artist or novice programmer can get the gist of Cg from this tutorial and learn to write interesting Cg programs.
You should know about computer graphics programming and the math involved. Basic algebra and trigonometry helps to appreciate several sections. Familiarity with the mathematics behind basic computer graphics vertex transformation and lighting models is assumed. You do not need to know either OpenGL or Direct3D though familiarity with either programming interface is very helpful. All the Cg examples described work with either OpenGL or Direct3D unless otherwise noted.
After the first chapter that introduces Cg, each following chapter is a short tutorial that introduces various Cg concepts and techniques. The tutorials build upon each other and we mean for you to read them in order.
This book gets you started but does not contain everything you will eventually want to know about Cg. This tutorial complements other documentation such as the Cg Toolkit User's Manual: a Developer's Guide to Programmable Graphics included with the Cg Toolkit. Please consult the users manual and other Cg documentation for further information.
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