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Computer Graphics
Dr. Amy ZhangAssistant Professor ofComputer ScienceUnited International College
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Welcome! Applications Introductions What is computer graphics? OpenGL and GLUT Overview
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Applications Movies and games Visualization
techniques for creating images, diagrams, or animations to communicate a message.
Digital photography Computer aided design (CAD)
the use of computer technology for the design of objects, real or virtual.
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Virtual reality a technology which allows a user to interact with a computer-
simulated environment, whether that environment is a simulation of the real world or an imaginary world.
Augmented reality a live direct or indirect view of a physical real-world
environment whose elements are merged with (or augmented by) virtual computer-generated imagery - creating a mixed reality.
Art
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Movies & Games
http://v.ku6.com/show/NzTgFbaxHf7FtACc.html
http://v.youku.com/v_show/id_XMTExMTAyMjY4.html
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Visualization
http://www.earthol.com/
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Digital Photography
http://www.easypano.com/virtual-tour-gallery.html#
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Computer Aided Design (CAD)
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Art
“Contact Water”Taisuke Murakami, 2001
Artificial Evolution for Computer GraphicsKarl Sims, SIGGRAPH ’91
Steven Parentehttp://www.alohablooms.com/atomica1.html
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What is Computer Graphics? Computer graphics
Computer graphics deals with all aspects of creating images with a computer
Graphics often combine text, illustration, and color, visual
presentations on surfaces, e.g. a wall, canvas, computer screen, paper, or stone to brand, inform, illustrate, or entertain.
Examples: photographs, drawings, line art, graphs, diagrams, typography, numbers, symbols, geometric designs, maps, engineering drawings, etc.
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General concepts Image
an artifact, usually two-dimensional, that has a similar appearance to some subject—usually a physical object or a person.
They may be captured by optical devices—such as cameras, mirrors, lenses, telescopes, microscopes, etc. and natural objects and phenomena, such as the human eye or water surfaces.
A digital image is a representation of a two-dimensional image using ones and zeros (binary).
Pixel the smallest piece of information in an image. normally arranged in a regular 2-dimensional grid, and are
often represented using dots or squares. The intensity of each pixel is variable; in color systems, each
pixel has typically three components such as red, green, and blue.
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Rendering the process of generating an image from a model, by means
of computer programs, is also used to describe the process of calculating effects in a video editing file to produce final video output.
Model a description of 3 dimensional objects in a strictly defined
language or data structure. It would contain geometry, viewpoint, texture, lighting, and shading information.
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Animation the rapid display of a sequence of images of 2-D or 3-D
artwork or model positions in order to create an illusion of movement.
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The graphics process Process to simulate interaction of light and
matter
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1.Modeling Vertex Polygon
a plane figure that is bounded by a closed path or circuit, composed of a finite sequence of straight line segments
ModelSurfaceVertex
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Graphical Models Geometric
2D and 3D objects Triangles, quadrilaterals, polygons Spheres, cones, boxes
Surface characteristics Color Texture
Composite objects Objects and their relationships to each other
Lighting, shading, animation, fog, etc.
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The basic idea Describe an object using surfaces, which are polygons
Triangles, quadrilaterals, whatever Important thing is that they are flat They must also be convex
Provide points in counterclock-wise order From the visible side
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2.Transformations Scaling
Translation
Rotation
Skew (Shear)
100
010
01 xd
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3.Texturing Texture - A bitmap image applied to a surface in computer
graphics Make 3D objects realistic
without texture with texture
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Texture/Displacement/Bump Map
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4.Viewing and projections Central projection Parallel projection
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5.Light and Color
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6. Illumination Models
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7. Shading models
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Rasterization Conversion of 3D model to 2D image
Projection Determine pixel Determine color
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8.Ray Tracing
Back tracing the ray coming into the viewer’s eye
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9. Curves & Surfaces
Free shape control/animation Less storage
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Animation
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OpenGL and GLUT Overview
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What Is OpenGL? Graphics rendering API
high-quality color images composed of geometric and image primitives
window system independent operating system independent
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OpenGL as a Renderer Geometric primitives
points, lines and polygons Image Primitives
images and bitmaps separate pipeline for images and geometry
linked through texture mapping Rendering depends on state
colors, materials, light sources, etc.
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Preliminaries Headers Files
#include <GL/gl.h> #include <GL/glu.h> #include <GL/glut.h> glut.h automatically include the others
Libraries gult3d.lib, glut32.dll
Enumerated Types OpenGL defines numerous types for
compatibility GLfloat, GLint, GLenum, etc.
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Compilation on Windows Get glut.h, glut32.lib, glut32.dll from web Create a console application Store glut.h in Additional include
directory Add opengl32.lib, glut32.lib to project
settings (under link tab) and store them in Additional library directory
Add glut32.dll to c:/windows/system32
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GLUT Basics Application Structure
Configure and open window Initialize OpenGL state Register input callback functions
render resize input: keyboard, mouse, etc.
Enter event processing loop
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Sample Programvoid main( int argc, char** argv ){ int mode = GLUT_RGB|GLUT_DOUBLE; glutInitDisplayMode( mode ); glutCreateWindow( argv[0] ); init(); glutDisplayFunc( display ); glutReshapeFunc( resize ); glutKeyboardFunc( key ); glutIdleFunc( idle ); glutMainLoop();}
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OpenGL Initialization Set up whatever state you’re going to
usevoid init( void ){ glClearColor( 0.0, 0.0, 0.0, 1.0 ); glClearDepth( 1.0 );
glEnable( GL_LIGHT0 ); glEnable( GL_LIGHTING ); glEnable( GL_DEPTH_TEST );}
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GLUT Callback Functions Routine to call when something happens
window resize or redraw user input animation
“Register” callbacks with GLUTglutDisplayFunc( display );glutIdleFunc( idle );glutKeyboardFunc( keyboard );
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Rendering Callback Do all of your drawing here
glutDisplayFunc( display );
void display( void ){ glClear( GL_COLOR_BUFFER_BIT ); glBegin( GL_TRIANGLE_STRIP ); glVertex3fv( v[0] ); glVertex3fv( v[1] ); glVertex3fv( v[2] ); glVertex3fv( v[3] ); glEnd(); glutSwapBuffers();}
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Idle Callbacks Use for animation and continuous update
glutIdleFunc( idle );
void idle( void ){ t += dt; glutPostRedisplay();}
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User Input Callbacks Process user input
glutKeyboardFunc( keyboard );void keyboard( char key, int x, int y ){ switch( key ) { case ‘q’ : case ‘Q’ : exit( EXIT_SUCCESS ); break; case ‘r’ : case ‘R’ : rotate = GL_TRUE; break; }}
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Summary There is one field called the primary
key which uniquely identify a record SQL can be used to
Create the tables Add, change, and delete data Query the DB for specific information
DB vs File System ER model
