Advanced Graphics Programming Techniques Using OpenGL

Organizer:
Tom McReynolds
SGI

Copyright ©1998 by Tom McReynolds and David Blythe.
All rights reserved

SIGGRAPH `98 Course

Abstract:

This advanced course demonstrates sophisticated and novel computer graphics programming techniques, implemented in C using the widely available OpenGL library.

By explaining the concepts and demonstrating the techniques required to generate images of greater realism and utility, the course helps students achieve two goals: they gain a deeper insight into OpenGL functionality and computer graphics concepts, while expanding their ``toolbox'' of useful OpenGL techniques.

Speakers

David Blythe David Blythe is a Principal Engineer with the Advanced Graphics Software group at SGI. David joined SGI in 1991 and has contributed to the development of RealityEngine and InfiniteReality graphics. He has worked extensively on implementations of the OpenGL graphics library and OpenGL extension specifications. David is currently working on high-level toolkits which are built on top of OpenGL as well as contributing to the continuing evolution of OpenGL.

Prior to joining SGI, David was a visualization scientist at the Ontario Centre for Large Scale Computation. David received both a B.S. and M.S. degree in Computer Science from the University of Toronto.

Email: blythe@sgi.com

Brad Grantham Brad Grantham currently contributes to the design and implementation of SGI's high-level graphics toolkits, including the Fahrenheit Scene Graph, a collaborative project with Microsoft and Hewlett-Packard. Brad previously worked on OpenGL Optimizer, Cosmo 3D, and IRIS Performer.

Before joining SGI, Brad wrote UNIX kernel code and imaging codecs. He received a Computer Science B.S. degree from Virginia Tech in 1992, and his previous claim to fame was MacBSD, BSD UNIX for the Macintosh.

Email: grantham@sgi.com

Tom McReynolds

Tom McReynolds is a software engineer in the Core Rendering group at SGI. He's implemented OpenGL extensions, done OpenGL performance work, and worked on IRIS Performer, a real-time visualization library that uses OpenGL.

Prior to SGI, he worked at Sun Microsystems, where he developed graphics hardware support software and graphics libraries, including XGL.

Tom is also an adjunct professor at Santa Clara University, where he teaches courses in computer graphics using the OpenGL library. He has also presented at the X Technical Conference, SIGGRAPH '96 and '97, SGI's 1996 Developer Forum, and at SGI's 1997 OpenGL Developer's Workshop.

Email: tomcat@sgi.com

Scott R. Nelson Scott R. Nelson is a senior staff engineer in the High Performance Graphics group at Sun Microsystems. He works in the development of new graphics accelerator architectures and contributed to the development of the GT, ZX, and Elite3D graphics accelerators.

Before joining Sun in 1988, Scott spent eight years at Evans & Sutherland developing graphics hardware. He received a B.S. degree in Computer Science from the University of Utah.

Email: Scott.Nelson@eng.sun.com

Other Contributers

Celeste Fowler (Author) Celeste Fowler is a software engineer in the Advanced Systems Division at SGI. She worked on the OpenGL imaging pipeline for the InfiniteReality graphics system and on the OpenGL display list implementation for InfiniteReality and RealityEngine.

Before coming to SGI, Celeste attended Princeton University where she did research on radiosity techniques and TA'd courses in computer graphics and programming systems.

Email: celeste@sgi.com

Simon Hui (Author) Simon Hui is a software engineer at 3Dfx Interactive, Inc. He currently works on OpenGL and other graphics libraries for PC and consumer platforms.

Prior to joining 3Dfx, Simon worked on IRIS Performer, a realtime graphics toolkit, in the Advanced Systems Division at SGI. He has also worked on OpenGL implementations for the RealityEngine and InfiniteReality. Simon received a B.A. in Computer Science from the University of California at Berkeley.

Email: simon@3dfx.com

Paula Womack (Author) Paula Womack is a software engineer in the Advanced Systems Division at SGI. She has managed the OpenGL group at SGI, and was also a member of the OpenGL Architectural Review Board (the OpenGL ARB) which is responsible for defining and enhancing OpenGL.

Prior to joining SGI, Paula worked on OpenGL at Kubota and Digital Equipment. She has a B.S. in Computer Engineering from the University of California at San Diego.

Email: womack@sgi.com

Linda Rae Sande (Production Editor) Linda Rae Sande is a production editor in Technical Publications at SGI. A graduate of Northern Arizona University (B.S. in Physics-Astronomy), she has taught college algrebra and physical science courses and worked in marketing communications and technical training. As co-author of two physics laboratory textbooks and author of several production manuals, Linda Rae has many years of experience in book production and production coordination.

Prior to SGI, she was a production coordinator at ESL-TRW responsible for the TravInfo and TransCal transportation project documentation and deliverables.

Email: lindarae@sgi.com

Dany Galgani (Illustrator) Dany Galgani has provided illustrations to Technical Publications at SGI for over 9 years. He has illustrated hardware and software manuals, from user's guides to programmer's manuals.

Before that, he did commercial art for advertising agencies and book publishers, including illustrating books in Ortho's ``Do-It-Yourself'' series.

Dany received his degree in the Arts from the University of Paris as well as a CPA.

Email: danyg@sgi.com

Course Syllabus

8:30 A

Introduction (McReynolds)

8:35 B

Visual Simulation (McReynolds)

1. Tiling Large Textures
2. Anisotropic Texturing
3. Developing LOD Models for Geometry
4. Billboarding
5. Light Points

9:20 C

Adding Realism (Blythe and McReynolds)

9:20

Object Realism (Blythe)

1. Phong Shading
2. Bump Mapping with Textures
3. Complex BDRFs Using Multiple Phong Lights

10:00 Break

10:15

Interobject Realism (McReynolds)

4.

Shadows

5.

Reflections and Refractions

6.

Transparency

11:00 D

Image Processing (Grantham)

1. OpenGL Image Processing
2. Image Warping with Textures
3. Accumulation Buffer Convolution
4. Antialiasing with Accumulation Buffer
5. Texture Synthesis and Procedural Texturing

12:00 Lunch

1:30 E

CAD (Nelson)

1. Constructive Solid Geometry
2. Meshing and Tessellation
3. Numerical Instabilities and Their Cure
4. Antialiasing Geometry

2:15 F

Scientific Visualization (Blythe)

1. Volume Rendering
2. Textures as Multidimensional Functions
3. Visualizing Flow Fields (line integral convolution)

3:00 Break

3:15 G

Graphics Special Effects (Grantham)

1. Stencil Dissolves
2. Color Space Operations
3. Photographic Techniques (depth of field, motion blur)
4. Compositing

4:00 H

Simulating Natural Phenomena (McReynolds)

1. Smoke
2. Fire
3. Clouds
4. Water
5. Fog

5:00 I

Summary, Questions and Answers (variable) All

 
• Contents
• List of Figures
• 12.3.1 Introduction
  • 1.1 OpenGL Version
  • 1.2 Course Notes and Slide Set Organization
  • 1.3 Acknowledgments
  • 1.4 Acknowledgments for 1997 Course Notes
  • 1.5 Course Notes Web Site
• 2 About OpenGL
• 3 Modeling
  • 3.1 Modeling Considerations
  • 3.2 Decomposition and Tessellation
  • 3.3 Generating Model Normals
    • 3.3.1 Consistent Vertex Winding
    • 3.3.2 Smooth Shading
  • Triangle-stripping
    • Greedy Tri-stripping
  • 3.5 Capping Clipped Solids with the Stencil Buffer
  • 3.6 Constructive Solid Geometry with the Stencil Buffer
• 4 Geometry and Transformations
  • 4.1 Stereo Viewing
    • 4.1.1 Fusion Distance
    • 4.1.2 Computing the Transforms
  • 9.2 Depth of Field
  • 4.3 The Z Coordinate and Perspective Projection
    • 4.3.1 Depth Buffering
  • 4.4 Image Tiling
  • 4.5 Moving the Current Raster Position
  • 4.6 Preventing Clipping of Wide Lines and Points
  • 4.7 Distortion Correction
• 5 Texture Mapping
  • 5.1 Review
    • 5.1.1 Filtering
    • 5.1.2 Texture Environment
  • 5.2 Mipmap Generation
  • 5.3 Texture Map Limits
  • 5.4 Anisotropic Texture Filtering
  • 5.5 Paging Textures
    • 5.5.1 Texture Subloading
    • 5.5.2 Paging Images in System Memory
  • 5.6 Transparency Mapping and Trimming with Alpha
  • 5.7 Billboards
  • 5.8 Rendering Text
  • 5.9 Texture Mosaicing
  • 5.10 Texture Coordinate Generation
  • 5.11 Color Coding and Contouring
  • 5.12 Annotating Metrics
  • 5.13 Projective Textures
    • 5.13.1 How to Project a Texture
  • 5.14 Environment Mapping
  • 5.15 Image Warping and Dewarping
  • 5.16 3D Textures
    • 5.16.1 Using 3D Textures
      • 3D Textures vs. Mipmaps
    • 5.16.2 3D Textures to Render Solid Materials
    • 5.16.3 3D Textures as Multidimensional Functions
  • 5.17 Line Integral Convolution (LIC) with Texture
    • 5.17.1 Sampling
    • 5.17.2 Using OpenGL to Create Line Integral Convolution (LIC) Images
    • 5.17.3 Line Integral Convolution Procedure
    • 5.17.4 Details
    • 5.17.5 Maximizing Contrast
    • 5.17.6 Going Farther
  • 5.18 Detail Textures
    • 5.18.1 Signed Intensity Detail Textures
    • 5.18.2 Making Detail Textures
  • 5.19 Gradual Cutaway Views
    • 5.19.1 Steps to Generating a Cutaway Shell
    • 5.19.2 Refinements
    • 5.19.3 Rendering a Surface Textured Shell
    • 5.19.4 Alpha Buffer Approach
    • 5.19.5 No Alpha Buffer Approach
  • 5.20 Procedural Texture Generation
    • 5.20.1 Filtered Noise Functions
    • 5.20.2 Generating Noise Functions
    • 5.20.3 High Resolution Filtering
    • 5.20.4 Spectral Synthesis
    • 5.20.5 Other Noise Functions
    • 5.20.6 Turbulence
    • 5.20.7 Example: Image Warping
    • 5.20.8 Generating 3D Noise
    • 5.20.9 Generating 2D Noise to Simulate 3D Noise
    • Trade-offs Between 3D and 2D Techniques
• 8.5.3 Blending
  • 6.1 Compositing
  • 6.2 Advanced Blending
  • 6.3 Painting
  • 6.4 Blending with the Accumulation Buffer
  • 6.5 Blending Transitions
• 11.9.4 Antialiasing
  • 7.1 Line and Point Antialiasing
  • 7.2 Polygon Antialiasing
  • 7.3 Multisampling
  • 7.4 Antialiasing With Textures
  • 7.5 Antialiasing with Accumulation Buffer
• 8 Lighting
  • 8.1 Phong Shading
    • 8.1.1 Phong Highlights with Texture
    • 8.1.2 Improved Highlight Shape
    • 8.1.3 Spotlight Effects using Projective Textures
    • 8.1.4 Phong Shading by Adaptive Tessellation
  • 8.2 Light Maps
    • 8.2.1 2D Texture Light Maps
    • 8.2.2 3D Texture Light Maps
  • 8.3 Other Lighting Models
  • 8.4 Global Illumination
  • 8.5 Bump Mapping with Textures
    • 8.5.1 Tangent Space
    • 8.5.2 Going for Higher Quality
    • Blending
    • 8.5.4 Why Does This Work?
    • 8.5.5 Limitations
  • 8.6 Choosing Material Properties
    • 8.6.1 Modeling Material Type
      • Dielectrics
      • Metals
      • Composite Materials
      • Other Materials
    • 8.6.2 Modeling Material Smoothness
• 9 Scene Realism
  • 9.1 Motion Blur
  • Depth of Field
  • 9.3 Reflections and Refractions
    • 9.3.1 Planar Reflectors
      • Planar Reflections and Refractions Using the Stencil Buffer
      • Planar Reflections using Texture Mapping
      • Interreflections
    • 9.3.2 Sphere Mapping
      • Using a Sphere Map
      • Generating a Sphere Map for Specular Reflection
      • Multipass Techniques and Interreflections
      • Other Sphere Mapping Techniques
      • Limitations of Sphere Mapping
  • 9.4 Creating Shadows
    • 9.4.1 Projection Shadows
      • Projection Shadow Trade-offs
    • 9.4.2 Shadow Volumes
      • Multiple Light Sources
      • Shadow Volume Trade-offs
    • 9.4.3 Shadow Maps
      • Shadow Map Trade-offs
    • 9.4.4 Soft Shadows by Jittering Lights
    • 9.4.5 Soft Shadows Using Textures
• 10 Transparency
  • Screen-Door Transparency
  • 10.2 Alpha Blending
  • 10.3 Sorting
  • 10.4 Using the Alpha Function
  • 10.5 Using Multisampling
• 11 Natural Phenomena
  • 11.1 Smoke
  • 11.2 Vapor Trails
  • 11.3 Fire
  • 11.4 Explosions
  • 11.5 Clouds
  • 11.6 Water
  • 11.7 Light Points
  • 11.8 Other Atmospheric Effects
  • 11.9 Particle Systems
    • 11.9.1 Representing Particles
    • 11.9.2 Particle Sizes
    • 11.9.3 Large and Small Points
    • Antialiasing
    • 11.9.5 ``Fat'' Particles
    • 11.9.6 Particle Systems in a Scene
  • 11.10 Precipitation
• 12 Image Processing
  • Introduction
    • 12.1.1 The Pixel Transfer Pipeline
    • 12.1.2 Geometric Drawing and Texturing
    • The Framebuffer and Per-Fragment Operations
    • 12.1.4 The Imaging Subset in OpenGL 1.2
  • 12.2 Colors and Color Spaces
    • 12.2.1 The Accumulation Buffer: Interpolation and Extrapolation
    • 12.2.2 Pixel Scale and Bias Operations
    • Look-Up Tables
      • Pixel Maps
      • The Color Table Extension
      • The Texture Color Table Extension
      • The Pixel Texture Extension
    • 12.2.4 The Color Matrix Extension
      • Equivalent Functionality Without SGI_color_matrix
      • Scale and Bias
      • Conversion to Luminance
      • Modifying Saturation
      • Hue Rotation
      • CMY Conversion
      • YIQ Conversion
  • 12.3 Convolutions
    • Introduction
    • 12.3.2 The Convolution Operation
      • Two-Dimensional Convolutions
      • Separable Filters
    • 12.3.3 Convolutions Using the Accumulation Buffer
    • 12.3.4 The Convolution Extension
    • 12.3.5 Useful Convolution Filters
      • Line detection
      • Gradient Detection (Embossing)
      • Smoothing and Blurring
      • High-pass Filters
      • Laplacian Filter
      • Sobel Filter
    • 12.3.6 Correlation and Feature Detection
  • 12.4 Image Warping
    • 12.4.1 The Pixel Zoom Operation
    • 12.4.2 Warps Using Texture Mapping
• 13 Volume Visualization with Texture
  • 13.1 Overview of the Technique
  • 13.2 3D Texture Volume Rendering
  • 13.3 2D Texture Volume Rendering
  • 13.4 Blending Operators
    • 13.4.1 Over
    • 13.4.2 Attenuate
    • 13.4.3 Maximum Intensity Projection
    • 13.4.4 Under
  • 13.5 Sampling Frequency
  • 13.6 Shrinking the Volume Image
  • 13.7 Virtualizing Texture Memory
  • 13.8 Mixing Volumetric and Geometric Objects
  • 13.9 Transfer Functions
  • 13.10 Volume Cutting Planes
  • 13.11 Shading the Volume
  • 13.12 Warped Volumes
• 14 Using the Stencil Buffer
  • 14.1 Dissolves with Stencil
  • 14.2 Decaling with Stencil
  • 14.3 Finding Depth Complexity with the Stencil Buffer
  • 14.4 Compositing Images with Depth
• 15 Line Rendering Techniques
  • 15.1 Wireframe Models
  • 15.2 Hidden Lines
    • 15.2.1 glPolygonOffset
    • 15.2.2 glDepthRange
  • 15.3 Haloed Lines
  • 15.4 Silhouette Edges
  • 15.5 Preventing Smooth Wide Line Overlap
  • 15.6 End Caps On Wide Lines
• 16 Tuning Your OpenGL Application
  • 16.1 What Is Pipeline Tuning?
    • Three-Stage Model of the Graphics Pipeline
    • 16.1.2 Finding Bottlenecks in Your Application
      • Application bottlenecks.
      • Geometry bottlenecks.
      • Rasterization bottlenecks.
  • 16.2 Optimizing Your Application Code
    • 16.2.1 Optimize Cache and Memory Usage
      • Minimizing Cache Misses.
    • 16.2.2 Store Data in a Format That is Efficient for Rendering
      • Minimizing State Changes.
    • Per-Platform Tuning
  • 16.3 Tuning the Geometry Subsystem
    • 16.3.1 Use Expensive Modes Efficiently
    • 16.3.2 Optimizing Transformations
    • 16.3.3 Optimizing Lighting Performance
    • Advanced Geometry-Limited Tuning Techniques
  • 16.4 Tuning the Raster Subsystem
    • 16.4.1 Using Backface/Frontface Removal
    • Minimizing Per-Pixel Calculations
      • Avoid Unnecessary Per-Fragment Operations.
      • Use Simple Fill Algorithms for Large Polygons.
      • Use the Depth Buffer Efficiently.
    • 16.4.3 Optimizing Texture Mapping
    • 16.4.4 Clearing the Color and Depth Buffers Simultaneously
  • 16.5 Rendering Geometry Efficiently
    • Using Peak-Performance Primitives
    • 16.5.2 Using Vertex Arrays
    • 16.5.3 Using Display Lists
    • 16.5.4 Balancing Polygon Size and Pixel Operations
  • 16.6 Rendering Images Efficiently
  • 16.7 Tuning Animation
    • 16.7.1 Factors Contributing to Animation Speed
    • 16.7.2 Optimizing Frame Rate Performance
  • 16.8 Taking Timing Measurements
    • 16.8.1 Benchmarking Basics
    • 16.8.2 Achieving Accurate Timing Measurements
    • 16.8.3 Achieving Accurate Benchmarking Results
• 17 Portability Considerations
  • 17.1 General Concerns
    • 17.1.1 Handle Runtime Feature Availability Carefully
    • 17.1.2 Extensions and OpenGL Versioning
    • 17.1.3 Source Compatibility Across OpenGL SDKs
    • 17.1.4 Characterize Platform Performance
  • 17.2 Windows versus UNIX
  • 17.3 3D Texture Portability
• 18 List of Demo Programs
• 19 GLUT, the OpenGL Utility Toolkit
• 20 Equations
  • 20.1 Projection Matrices
    • 20.1.1 Perspective Projection
    • 20.1.2 Orthographic Projection
    • Perspective z-Coordinate Transformations
  • 20.2 Lighting Equations
    • 20.2.1 Attenuation Factor
    • 20.2.2 Spotlight Effect
    • 20.2.3 Ambient Term
    • 20.2.4 Diffuse Term
    • 20.2.5 Specular Term
    • 20.2.6 Putting It All Together
• 21 References
• References
• About this document ...