1. Advanced Graphics Algorithms Ying Zhu Georgia State University
Lecture 02
Overview of Computer Graphics Programming

2. Computer Graphics: A Brief History
William Fetter of Boeing coins the term “Computer Graphics” (1960)
Basic computer graphics algorithms/concepts are introduced: hidden line detection, homogeneous coordinates, line drawing, back-face culling, parametric curves & surfaces, etc.
Spacewars, first video game, is developed at MIT (1961)
SketchPad: first interactive computer graphics software (1962)
First Head Mounted Display is developed at MIT (1968)
Bell Labs builds first frame buffer (3 bits)
First use of CGI for commercials – MAGI for IBM (1969)
SIGGRAPH is formed (1969)
Spacewars
Image courtesy MIT Media Lab

3. Computer Graphics: A Brief History
Many fundamental computer graphics algorithms/technologies are introduced: visible surface detection, Gouraud shading, Phone shading, Z-buffer, curved surface rendering, texture mapping, reflectance and environment mapping, anti-aliasing, curved shadow, bump mapping, ray tracing, keyframe based animation, etc.
First SIGGRAPH conference (1973)
Microsoft is founded (1974); Special effects powerhouse, Industrial Light & Magic, is founded (1975)
The first flight simulator for Apple II is released (1978) (later purchased by Microsoft)
First flight simulator
Image courtesy simflight.com

4. Computer Graphics: A Brief History
Many major companies in the graphics field are founded: Silicon Graphics Inc., ATI, SUN, Pixar, Adobe, AutoDesk, Alias, Softimage, Side Effects, etc.
More graphics algorithms are introduced: radiosity, motion capture, motion blur, morphing, etc.
The birth of RenderMan (1988)
Wavefront – the first commercially available 3D software package (1984)
AutoCAD 1.0 (1982)
Tron (1982): 1st film to make extensive use of computer graphics
Tron

5. Computer Graphics: A Brief History
The release of major 3D graphics libraries: OpenGL, DirectX, Java3D
Image based rendering attracts attention
The release of major 3D modeling & animation packages: 3D Studio, 3D Studio Max, Maya, etc.
The rise and fall of SGI
NVIDIA releases first Graphics Processing Unit (1999)
Increasing use of 3D special effects in feature films: Terminator 2, Titanic, etc.
First 3D computer animated feature film: Toy Story by Pixar
The release of Doom and Quake
CAVE: immersive virtual environment
Titanic

6. Computer Graphics: A Brief History
2000 – present
Powerful Graphics Processing Units on PC graphics card: NVIDIA Geforce3/4/FX/6800/7800/8800, ATI Radeon 9700/9800/X800/X850/X1950
High level shading languages: Cg, HLSL, GLSL, Sh, etc.
New generation game console: Xbox/360, Playstation2/3
Widespread use of CGI special effects in feature films: War of the Worlds, Lord of the Rings, Spiderman, Matrix, Finding Nemo, Shrek, The Cars, etc.

7. Creating 3D Graphics Content
Different ways to create graphics content
If you want to create non-interactive 3D animations
Use graphics modeling/animation tools: 3DS Max, Maya, Blender, etc.
If you want to create interactive 3D applications (game, training & simulation program)
A combination of both modeling/animation tools and programming
C/CPP + scene graph + OpenGL/D3D + Shader

8. Graphics Libraries (APIs)
3D graphics applications are built on top of graphics libraries
A collection of graphics routines that an application program can call
The APIs hide the underlying complexity of graphics hardware and/or lower level APIs
Large scale graphics applications are usually built on top of high level graphics APIs

9. Graphics Libraries (APIs)
High level APIs are implemented on top of low level graphics APIs
Low level APIs control graphics hardware through graphics drivers
Between low level graphics APIs and graphics drivers there are shader libraries

10. High Level Graphics APIs
Also known as Scene Graph APIs
Non-real-time oriented APIs
Java3D
VRML & X3D
Open Inventor
Renderman

11. High Level Graphics APIs
Real-time oriented APIs
3D graphics and game engines
Torque Game Engine
OGRE
OpenGL Performer
Open Scene Graph
OpenSG
Many proprietary high level APIs

12. Game Engines Game engine
Graphics API designed specifically for game development
Contains all non-content related functions/elements

13. Game Engine Game Architecture Gameplay Game engine Tools & Editor
Graphics Hardware

14. Modern Game Engine Features
Scene management
Culling,
Rendering
Bump mapping
Shadow
Collision
Decals AI
Particle systems, etc.
Shader management

15. Game Engines There are hundreds of game engines
Most popular game engines
Torque Game Engine (commercial)
OGRE (open source)
For a comprehensive list, check out

16. Torque Game Engine
A very popular game engine with multi-player network code, indoor/outdoor rendering engines, skeletal animation, drag and drop GUI creation, a built in world editor, and a C- like scripting language.

17. OGRE Object-oriented Graphics Rendering Engine
A scene-oriented, flexible 3D engine written in C++ designed to make it easier and more intuitive for developers to produce games and demos using 3D hardware.

18. OGRE example

19. OGRE example

20. Java3D High level object-oriented scene graph API
Platform independent, implemented on top of Direct3D or OpenGL
Try to meet a wide variety of application requirements
Real-time performance
Object modeling
Input devices support
Stereoscopic vision

21. JOGL Java OpenGL (JOGL) https://jogl.dev.java.net/
A wrapper library that allows OpenGL to be used in the Java programming language

22. VRML & X3D VRML = Virtual Reality Modeling Language X3D
HTML like language for describing 3D shapes and interaction
X3D
Next generation open standard for 3D on the web
Officially replaced VRML in July 2004
X3D supports XML for tight integration with Web technologies and tools

23. OpenGL Performer http://www.sgi.com/products/software/perfor mer/
A graphics API developed by SGI for real-time visual simulation and other performance oriented applications
Implemented on top of OpenGL, with performance as the first priority
mer/
Performer has great influence on other real-time graphics APIs
E.g. Open Scene Graph (

24. Why so many scene graph APIs & game engines?
Different target applications
Real-time vs. non-real-time applications
Application specific optimizations
Application specific entities
E.g. different game genres require different game engines

25. Why so many scene graph APIs & game engines?
Language and platform considerations
Platform specific optimizations
Open source vs. proprietary APIs
Integration of new technologies
Not necessarily a good thing
Lack of documents & sample code

26. Low Level Graphics APIs
Directly handles 3D rendering
Very efficient implementation
Only two major low level 3D graphics APIs
OpenGL
Direct3D (part of DirectX)
Comparison of Direct3D and OpenGL
t3D_and_OpenGL

27. Direct3D Part of Microsoft’s DirectX libraries
Including Direct3D, DirectInput, DirectSound, etc.
Designed for real-time graphics applications
Computer game
Home entertainment
Primary choice for game development
Latest version is DirectX 10
Only supported on MS Windows platform

28. Using Direct3D Benefits Drawbacks
Supported by most of the graphics hardware
Better game support
Better integration with other MS stuff (e.g. .Net)
Maintained by one single company
Quick to add new features to Direct3D
Drawbacks
Somewhat more difficult to learn than OpenGL
Windows only

29. OpenGL Platform independent graphics API Window system independent
MS Windows, Linux, IRIX, Solaris, Mac, etc.
Window system independent
MS Windows, X Window
Maintained by KHRONOS group (an industry consortium)
Members include 3Dlabs, AMD, NVIDIA, Intel, Google, etc.
Current specification: OpenGL 3.0

30. Using OpenGL Benefits Drawbacks http://www.opengl.org/ Open standard
Supported by all the graphics cards
Supported by all the platforms
Lots of books, tutorials, and samples available
Most of the mainstream 3D graphics textbooks use OpenGL
Drawbacks
Historically, OpenGL is often slow to add new features
Users are often forced to use OpenGL extensions

31. OpenGL Extension
OpenGL extensions provide new rendering features above and beyond the features specified in the official OpenGL standard
To keep the OpenGL API current with the latest innovations in graphics hardware and rendering algorithms
Different kind of extensions:
Extensions ratified by the ARB: GL_ARB_multitexture();
Extensions agreed on by multiple vendors: GL_EXT_abgr();
Vendor specific extensions: GL_NV_register_combiners();

32. OpenGL Extension
To find out what OpenGL extensions your graphics card supports, download and install Glview utility (OpenGL extension viewer)

33. OpenGL Related APIs GLU (OpenGL Utility Library)
Mostly modeling related functions: NURBS, tessellators, etc.
Part of OpenGL
GLX: connecting OpenGL with X Window
WGL: connecting OpenGL with MS Windows

34. OpenGL Related APIs GLUT (OpenGL Utility Toolkit)
implements a simple windowing application programming interface (API) for OpenGL
makes it easier to learn OpenGL programming
designed for constructing small to medium sized OpenGL programs
Binary files:
Reference manual: 3.html

35. GPU and Shader
Graphics Processing Units are the microprocessors on the newer graphics cards
Nvidia, AMD, and Intel are the main GPU vendors
You can write programs that runs on GPU using a special programming language
These programs are called shaders
The programming languages are called shading languages

36. Shader Programming Why use shaders? Faster and more flexible
To implement features that are not available on OpenGL or Direct3D
Take advantage of GPU, which is is optimized for graphics applications
Faster and more flexible
High level shading languages
Cg, HLSL, OpenGL SL, Sh
Load, compile, and run shader programs from OpenGL or DirectX programs

37. OpenGL Files
OpenGL files comes with MS Windows and/or Visual Studio installation
Header files
gl.h, glu.h
Glut.h (needs to be downloaded)
Static libraries
Opengl32.lib, glu32.lib
glut32.lib (needs to be downloaded)
DLLs
C:\windows\system32
Opengl32.dll, glu32.dll
glut32.dll (needs to be downloaded)

38. How to compile OpenGL/GLUT programs?
ll04-22C151/howto/winGLUT.html
ACTIVE_COMPUTER_GRAPHICS/FOURTH _EDITION/vc

39. Sample OpenGL programs
Examples from “OpenGL Programming Guide”
edbook/
OpenGL code samples:
Simple code samples: imple/

40. A Simple OpenGL Program (1)
#include <GL/glut.h>
void display(void) {
/* clear all pixels */
glClear (GL_COLOR_BUFFER_BIT);
/* draw white polygon (rectangle) with corners at
* (0.25, 0.25, 0.0) and (0.75, 0.75, 0.0) */
glColor3f (1.0, 1.0, 1.0);
glBegin(GL_POLYGON);
glVertex3f (0.25, 0.25, 0.0);
glVertex3f (0.75, 0.25, 0.0);
glVertex3f (0.75, 0.75, 0.0);
glVertex3f (0.25, 0.75, 0.0);
glEnd();

41. A Simple OpenGL Program (2)
/* start processing buffered OpenGL routines */
glFlush (); }
void init (void) {
/* select clearing color */
glClearColor (0.0, 0.0, 0.0, 0.0);
/* initialize viewing values */
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);

42. A Simple OpenGL Program (3)
/* Declare initial window size, position, and display mode (single
buffer and RGBA). Open window with "hello" in its title bar. Call
initialization routines. Register callback function to display graphics.
Enter main loop and process events. */
int main(int argc, char** argv) {
glutInit(&argc, argv);
glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize (250, 250);
glutInitWindowPosition (100, 100);
glutCreateWindow ("hello");
init ();
glutDisplayFunc(display);
glutMainLoop();
return 0; /* ANSI C requires main to return int. */ }

43. Next lecture
3D graphics pipeline