1. Overview of Computer Graphics Chapter 1

2. Bird’s Eye View  Overview of Computer Graphics –Basic concept of computer graphics, system, programming platforms, and standard  2D Graphics: Basics  2D Graphics: Rendering Details  2D Graphics: Advanced topics 2

3. Objectives  To understand the basic objectives and scope of computer graphics  To identify computer graphics applications  To understand the basic structures of 2D and 3D graphics systems  To understand evolution of graphics programming environments  To identify common graphics APIs  To understand the roles of Java language, Java 2D and Java 3D packages  To identify computer graphics related fields 3

4. Computer Graphics 4 Modeling: Creating a virtual world. Rendering: Generating a visual image of a scene.

5. Graphics System: Components and Functions  Modeler  Renderer  Hardware device  Virtual World  View  Geometry  Transformation  Illumination  Interaction  Animation 5

6. Applications  User interface  Computer Aided Design  Medical systems  Video games  Movies  … 6

7. Graphics Programming Environment 7 Hardware (direct register/video buffer programming) OS (WIN32, X, Mac OS) Graphics Standard (GKS, PHIGS, OpenGL) Platform Independent (Java 3D)

8. Hardware Level 8 Determination of the pixels on a circle. From the current pixel, the next pixel will be either to the “east” or to the “southeast”. F Program the graphics hardware directly F Typically written in low-level languages F Manipulate the hardware registers and video buffers F Highly machine-dependent F Example: MS-DOS graphics program Source

9. Operating System Level 9 F Program through OS graphics support F Do not directly manipulate graphics hardware F Portable on the same platform F Example: WIN32 SourceRun hdc = BeginPaint (hwnd, &ps); GetClientRect (hwnd, &rc); cx = (rc.left + rc.right)/2; cy = (rc.top + rc.bottom)/2; if (rc.bottom - rc.top < rc.right - rc.left) r = (rc.bottom - rc.top) / 2 - 20; else r = (rc.right - rc.left) / 2 - 20; Ellipse(hdc, cx-r, cy-r, cx+r, cy+r); EndPaint (hwnd, &ps);

10. GKS and PHIGS 10 Graphics Kernel System Programmer’s Hierarchical Interactive Graphics System F International standard (ISO 7942 1985) F 2D graphics F Common language binding: FORTRAN F Example: A FORTRAN GKS program to draw a circle F ISO 9592 1991 F 3D graphics Source

11. OpenGL 11 Source F Popular 2D/3D graphics API F over 200 functions F Common language binding: C F Example: An OpenGL program to draw a circle GLU GLUT GL Run

12. OpenGL 12 Source 3D Example: A spinning sphere Run

13. Java 13 Java 3D OpenGL Java APIs Display driver Graphics card Display Graphics application Java VM OS Java 3D based graphics systems

14. Java Programming Languages  Simple  Object Oriented (OOP)  Write once, run anywhere  Multithreaded 14 Java graphics: AWT / Swing Source

15. JOGL  OpenGL Java language binding  No OOP modeler 15 Source 1.Create a GLCanvas or GLJPanel object through the GLDrawableFactory class. 2.Add a GLEvent listener to the canvas object. 3.Implement the listener by implementing the four methods: init, display, reshape, and displayChanged.

16. Steps Required to Set Up GUI Event Handling  Several coding steps are required for an application to respond to events –Create a class for the event handler –Implement an appropriate event-listener interface –Register the event handler 16

17. Events and Listeners 17 Component A component object may generate an event Listener A corresponding listener object is designed to respond to the event Event When the event occurs, the component calls the appropriate method of the listener, passing an object that describes the event

18. Java 2D  Standard package of Java 2 platform  Improvements over AWT  Graphics2D class 18 Source

19. Java 3D  High-level API  Scene graph  Modeler/Renderer  Java Integration 19 Source

20. Other Fields Related to Graphics  Image processing  Computer vision  Mathematics –Analytic geometry –Linear algebra 20