Introduction to Computer Graphics ,

1. CSC 307 1.0
Graphics Programming
Budditha Hettige
Department of Statistics and Computer Science

2. Graphics Programming
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3. Common Uses for Computer
Graphics
• Applications for real-time 3D graphics range from
interactive games and simulations to data visualization
for scientific, medical, or business uses
– Military flight simulators
– Computer-aided design (CAD)
– Architectural or civil planning
– Scientific visualization
– Entertainment
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4. Movies
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5. Games
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6. Simulation
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7. CAD-CAM & Design
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8. Architecture
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9. Virtual Reality
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10. Visualization
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11. Medical Imaging
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12. Graphics System
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User ProgramUser Program IO DevicesIO Devices
Graphics API
Graphics
System
Graphics
System
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13. Graphics Designing
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14. Graphics: Conceptual Model
Real Object
Real Object
Human Eye
Human Eye
Display
Device
Graphics System
Synthetic
Model
Synthetic
Camera
Real Light
Synthetic
Light Source
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15. OpenGL
• Standard specification defining a cross-language, cross-
platform API
• Is not a programming language
• Writing applications that produce 2D and 3D computer
graphics
• A software interface to graphics hardware
• Designed and optimized for the display and
manipulation of 3D graphics
• Developed by Silicon Graphics Inc. (SGI) in 1992
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16. OpenGL-Graphics rendering API
• Rendering API
– High-quality color images composed of geometric
and image primitives
– Window system independent
– Operating system independent
• OpenGL Pipeline
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17. OpenGL Architecture
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Display
List
Polynomial
Evaluator
Per Vertex
Operations &
Primitive
Assembly
Rasterization
Per Fragment
Operations
Frame
Buffer
Texture
Memory
CPU
Pixel
Operations
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18. Software & Hardware Interfaces
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Software Interface Hardware Interface
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19. OpenGL and Related APIs
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GLUT
GLU
GL
GLX, AGL
or WGL
X, Win32, Mac O/S
software and/or hardware
application program
OpenGL Motif
widget or similar
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20. Related APIs
• AGL, GLX, WGL
– glue between OpenGL and windowing systems
• GLU (OpenGL Utility Library)
– part of OpenGL
– NURBS, tessellators, quadric shapes, etc.
• GLUT (OpenGL Utility Toolkit)
– portable windowing API
– not officially part of OpenGL
• Initial header inclusions (for Windows)
– #include<windows.h>
– #include<gl/gl.h>
– #include<gl/glu.h>
– #include <GL/glut.h>
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21. Function-Naming Conventions
• All OpenGL functions take the following
format
<Library prefix><Root command><Optional argument
count><Optional argument type>
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22. OpenGL data types
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23. 2D Coordinates
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24. Coordinate Clipping
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25. Viewports
• Mapping Drawing Coordinates to Window
Coordinates
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viewport defined as twice the size of the clipping area
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26. Viewports
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viewport that matches the clipping area
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27. OpenGL 3-D coordinates
• Right-handed system
• From point of view of camera looking out into
scene:
 +X right, -X left
 +Y up, -Y down
 +Z behind camera, -Z in front
• Positive rotations are counterclockwise around
axis of rotation
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OpenGL Geometric Primitives
GL_QUAD_STRIP
GL_POLYGON
GL_TRIANGLE_STRIP
GL_TRIANGLE_FAN
GL_POINTS
GL_LINES
GL_LINE_LOOPGL_LINE_STRIP
GL_TRIANGLES
GL_QUADS
Primitives are one- or two-dimensional entities or
surfaces such as points, lines, and polygons
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29. The Vertex—A Position in Space
• Each corner of the any primitive is called a
vertex. Ex: three-dimensional cube consists of
six two dimensional squares, each placed on a
separate face
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30. Projections: Getting 3D to 2D
• Orthographic Projections
• Perspective Projections
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31. RGB Color Space
Green
(1,0,0)
Blue
(0,0,1)
Red
(1,0,0)
Yellow
(1,1,0)
Magenta
(1,0,1)
Blk
Cyan
(0,1,1)
White
(1,1,1)
G
B
R
Image: Pixel maps to color
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32. Common Composite Colors
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