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CSC 307 1.0

Graphics Programming

Budditha Hettige

Department of Statistics and Computer Science

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Graphics Programming

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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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Movies

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Games

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http://localhost/var/www/apps/conversion/tmp/scratch_3/Fig/halflife2_pc73103_traptown_qt.mov

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Simulation

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CAD-CAM & Design

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Architecture

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Virtual Reality

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Visualization

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Medical Imaging

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Graphics System

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User Program IO Devices

Graphics API

Graphics

System

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Graphics Designing

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Graphics: Conceptual Model

Real Object

Real Object

Human Eye

Human Eye

DisplayDevice

Graphics System

SyntheticModel

SyntheticCamera

Real Light

SyntheticLight Source

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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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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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OpenGL Architecture

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Display

List

Polynomial

Evaluator

Per Vertex

Operations &

Primitive

Assembly

RasterizationPer Fragment

Operations

Frame

Buffer

TextureMemory

CPU

Pixel

Operations

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Software & Hardware Interfaces

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Software Interface Hardware Interface

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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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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

#include

#include

#include

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Function-Naming Conventions

All OpenGL functions take the following

format

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OpenGL data types

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2D Coordinates

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Coordinate Clipping

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Viewports

Mapping Drawing Coordinates to WindowCoordinates

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viewport defined as twice the size of the clipping area

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Viewports

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viewport that matches the clipping area

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OpenGL 3-D coordinates

Right-handed system

From point of view of camera looking out intoscene:

+X right, -X left +Y up, -Y down

+Zbehind 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_POINTSGL_LINES

GL_LINE_LOOPGL_LINE_STRIP

GL_TRIANGLES

GL_QUADS

Primitives are one- or two-dimensional entities orsurfaces such as points, lines, and polygons

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The VertexA 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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Projections: Getting 3D to 2D

Orthographic Projections

Perspective Projections

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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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Common Composite Colors

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