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Boundary Simulation

Department of CSE Page 1

CHAPTER 1

INTRODUCTION

Computer Graphics is concerned with all aspects of producing pictures or images using

a computer. Interactive Computer Graphics (ICG) involves two way communications between

the user and the computer.

1.1 Aim of the Project

The aim of project is how to use the GLU polygon tessellator to determine the 2D

boundary of OpenGL rendered objects.

1.2Project Description

The project boundary simulation is implemented on the basic platform OpenGL which

included in our curriculum. This project is developed using various APIs. This project makes use of

library called as GLUT.

The basic concept of the project involves the use of various textures and primitives to design different

screen savers. The user is provided with a menu which can be viewed by right clicking the mouse. The

project is coded for various options which can be done by right clicking the mouse on previously

developed pattern. Various options present in the menu are:

Torus: select a torus object.

Cube:select a cube object.

Sphere:select a sphere object.

Icosahedron:select a icosahedrons object.

Teapot:select the teapot.

Change dimension:change the dimension of object from 2D to 3D and vice versa.

Exit:exit from the window.


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1.3 COMPUTER GRAPHICS

The dominant characteristic of this new millennium is how computer and communication

technologies have become dominant forces in our life. Activities as wideranging as

filmmaking, publishing, banking, and education continue to undergo revolutionary changes as

these technologies alter the ways in which we conduct our daily activities. The combination of

computers, networks, and the complex visual systems, through computer graphics, has led to

new ways of displaying information, seeing virtual worlds and communicating with people and

machines

Computer graphics is concerned with all aspects of producing pictures or images using a

computer. The field began humbly almost 50 years ago, with a display of few lines on a

cathode-ray-tube; now, we can create images by computer that are indistinguishable from

photographs of real objects. We routinely train pilots with simulated airplanes, generating

graphical displays of a virtual environment of real time. Featurelength movies made entirely

by computer have been successful, both critically and financially. Massive multiplayer games

can involve tens of thousands of concurrent participants.

1.4

APPLICATIONS OF COMPUTER GRAPHICS

Display of information

Design

Simulation and animation

User interfaces

DISPLAY OF INFORMATION

Classical graphics technique arose as a medium to convey information among people. We have

computer plotting packages that provide a variety of plotting techniques and color tools that

can handle multiple large data sets.

The field of information visualization is becoming increasingly more important as we

have to deal with understanding complex phenomena from problems in bioinformatics

to detecting security threats.

The field of scientific visualization provides graphical tools that help the researchersinterpret the fast quantity of data that they generate.


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Medical imaging posses interesting and important data analysis problems. Modern

imaging technologies such as computed tomography (CT), magnetic resonance imaging

(MRI), ultrasound and positron emission tomography (PET)-generate 3D data that must

be subjected to algorithmic manipulation to provide useful information.

DESIGN

Professions such as engineering and architectures are concerned with design. Starting

with a set of specifications, engineers and architects seek a cost effective and esthetical

solution that satisfies the specifications.

The use of interactive graphical tools in computer aided design (CAD) pervades fields

including as architecture , medical engineering , the design of very-large-scale

integrated (VLSI) circuits, and the creation of characters for animation.

SIMULATION AND ANIMATION

Graphics system evolved to be capable of generating sophisticated images in real

time, engineers and researchers began to use them as simulators. One of the most

important uses has been in the training of pilots. The use of special PLSI chips has led

to a generation of arcade, games as sophisticated as flight simulators.

The simulator can be used for designing the robot, planning its path, and simulating its

behaviour in complex environment. The success of flight simulators led to the use of

computer graphics for animation in the TV, motion picture and advertising industries.

Entire animated movies can now be made by computers at a cost less than that of

movies made with tradition hand animation techniques.

The graphic technology for games, both in the form of the graphics processing units

that are on graphics cards in personal computers and in game boxes such as the Xbox

and the play stations, is being used for simulation rather than expensive specialized

hardware.

USER INTERFACES

Our interaction with computers has become dominated by a visual paradigm that includes

windows, icons, menus and a pointing device such as a mouse. From users perspective,

winding system such as the X window system, Microsoft windows, and the Macintosh Os x

defer only in derails


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Millions of people have become Internet users. Their access is through graphical

network browsers, such as Firefox and Internet explorer. Although we are familiar with

style of graphical user interface used on most workstations, advances in computer

graphics have made possible other forms of interfaces. OpenGL doesn't provide high-level commands for describing models of three-

dimensional objects. Such commands might allow you to specify relatively complicated

shapes such as automobiles, parts of the body, airplanes, or molecules.

With OpenGL, you must build up your desired model from a small set ofgeometric

primitives- points, lines, and polygons.

program

Figure1.1 Application Programmers Model of Graphics System

The interface between an application program and a graphics system can be specified

through a set of functions the resides in a graphics library .These specification are

called the application programmers interface (API).The application programmers

model of the system is shown in Figure 1.1. The application programmer sees only the

API and is thus shielded from the details of both the hardware and the software

implementation of the graphics library.

1.5 OPENGL

OpenGL is a library of functions for fast 3D rendering. OpenGL does not have any way to

obtain input from user. As a software interface for graphic hardware OpenGL main purpose is

to render 2D and 3D objects into frame buffer. These objects are described as a sequence of

vertices or pixels. OpenGL performs several processing steps of these data to convert it into

pixel to form the final desired image in the frame buffer.

Application

program

Graphics

library

(API)

DriversMouse

Display


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OpenGL is a hardware and system independent interface. An OpenGL application will work on

every platform as long as there as an installed implementation. Because their systemsindependent there are no function to create windows etc, but there are helper functions for each

platform. A very useful thing is GLUT.

1.5.1 GLUT

It is a complete API written by Mark Kilgard, which lets us create windows and handle

the messages. It exists for several platforms that mean that a program, which uses GLUT,

can be compiled on many platforms without any changes in the code.

Figure 1.2 Library organization

ADDITIONAL LIBRARIES

There are two libraries that we have that came with OpenGL:

1: GLU: It is a set of utility functions. They are easy way of doing things that is tedious with

raw OpenGL.

2: GLX: It allows you to open up X window and link it up with OpenGL so that it will draw to

that window.

OpenGL

application

GLU

GL

GLUT

GLX

Xlib, Xtk Frame

Buffer


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HOW OPENGL WORKS

To be hardware independent OpenGL provides its own data types. They all begin with GL.

Example: GLfloat, Glint

There are also many symbolic constants ;they all begin with GL,like

GL_POINTS,GL_POLYGON.

Finally commands have prefix gl. Example: glVertex3f.

OPENGL VERSION AND EXTENSIONS

One of the main features of OpenGL is that the API has been very stable there were upgrades

from OpenGL 1.0 through OpenGL 1.5 that were released over a 10-year period, each of which

was compatible with previous releases. OpenGL 2.0, which was released in 2004, was a major

upgrade but still retains code compatibility with earlier versions. The current release is

OpenGL 2.1. Thus, any program written on an older version of OpenGL runs as expected on

later version. Changes to OpenGL reflect advances in hardware that became common to many

graphics processors

1.6 Graphics Function

Function calls Outputs

Data Input

Figure 1.3

Our basic model of a graphics package is a black box, a term that engineers use to

denote a system whose properties are described only by its inputs and outputs. We describe an

API through the functions in its library. Some of the functions are:

The primitive functions define the low-level objects or atomic entities that our system

can display.

Attribute functions allow us to perform operations ranging from choosing the color

with which we display a line segment, to picking a pattern with which to fill the inside

of a polygon, to selecting a typeface for the titles of a graph.

Application

programs

Graphics

system

ip /op

devices


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Transformation function allows carrying out transformations of objects, such as

rotation, translation, and scaling.

A set of input functions allow us to deal with the diverse forms of input that

characterize modern graphics systems. The control functions enable us to communicate with the window systems, to initialize

our programs, and to deal with any errors that take place during the execution of

programs.


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CHAPTER 2

REQUIREMENT SPECIFICATION

A software requirement definition is an abstract description of the services which thesystem should provide, and the constraints under which the system must operate. It should only

specify the external behaviour of the system.

2.1 Functional Requirements

Functional Requirements defines the internal working of the software, i.e., the

calculations, technical details, data manipulation and processing and other specific

functionality that show how the cases are to be satisfied and how they are supported by non-

functional requirements, which impose constraints on the design or the implementation.

The following are the Functional requirements

The ability to display the menu when the ENTER button is clicked.

When the corresponding menu is selected, the corresponding option should be

performed.

Move the vehicle only when green light is on .

Stop the vehicle when red light is on .

Provide the signal simulation environment to the user .

2.2 Non Functional Requirements

Nonfunctional requirements are requirements which specify criteria that can be used to

judge the operation of the system, rather than specific behaviors. This should be contrasted

with functional requirements that specify specific behavior or functions. Typical nonfunctional

requirements are reliability and scalability. Nonfunctional requirements are constraints,

quality attributes and quality of service requirements.

The following are the Non Functional Requirements:

The application should provide a simple interface


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2.3 Software and Hardware Requirements

Software Requirements

1. OPERATING SYSTEM : Windows XP or Higher version

2. FRONT END : Microsoft Visual Studio 2005(.NET 2.0).

3.

CODING LANGUAGE : C, C++

Hardware Requirements

This software requires a hardware requirement of a processor of speed 333 MHz, 32MB or

above RAM capacity, a graphic card, a Keyboard and a min.100kb of hard disk space.

1.

SYSTEM : Pentium IV 2.4 GHz or above

2. HARD DISK : 20 GB or above

3. MONITOR : 15 VGA color

4. RAM : 256 MB

5. Micro Processor : Pentium 4

6.

keyboard : 1

7. CPU Clock : 166MHZ Onwards


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CHAPTER 3

DESIGN

3.1 InitializationInitialize to interact with the windows. Initialize the display mode- double buffer and depth

buffer. Initialize the various callback functions for creating 3d objects, mouse interface and

keyboard interface, for displaying and selecting the interactive options, for selecting option

from menu or to rotate the object. Initialize the window position and size and create the

window to display the output.

3.2 Flow of control

Start

Main

Initialise openGL()

Callback function.

MENU

C1


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\

Figure 1.4 Flow chart

TORUS

CUBE

ISOHEDRON

TEAPOT

CLOSE

Display

Solid torus

Display

Cube

Display

Tea pot

Display

Isohedron

KEYBOARD

up down left right

Rotate

upward

Rotate

down

Rotate

right

Rotate

left

C1

STOP


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CHAPTER 4

IMPLEMENTATION

To implement the current system we have used different functions of our project which are as

follows:

4.1 USER FUNCTIONS

Render():is the process of generating an image from a model, by means of a software

program. The model is a description of three dimensional objects in a strictly defined

language or data structure. It would contain geometry, viewpoint, texture and lighting

information.

Display():the function is called by glutDisplayfunc(), this function enable and disable

the lighting,depth test and cull_face according to the value of boundary.

Special():This function gets the input from the keyboard and rotate the object in

different axis . It checks for the keys such as up, down, left and right.

determineBoundary(): this functionfind out the external edges (boundary) of the

given object.

Text():the function prints a text in the screan.

Menu() :The function receive the value from the menu displayed on screan and do the

task according to the case. And exits from the window when clicked on close.

4.2 BUILT IN FUNCTIONS

GlTranslate ():Alters the current matrix by a displacement of(x,y,z).TYPE is either

GLfloat or GLdouble.

glutCreateMenu():Returns an identifier for a top level menu and register the callback

function f that returns an integer value corresponding to the menu entry selected.

GlutAddMenuEntry ():glutAddMenuEntry adds a menu entry to the bottom of the

current menu. The string name will be displayed for the newly added menu entry. If

the menu entry is selected by the user, the menu's callback will be called passing value

as the callback's parameter.

GlLoadIdentity ():replaces the current matrix with the identity matrix. It issemantically equivalent to calling glLoadMatrix with the 4X4 identity matrix.


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GlClearColor (): specifies the red, green, blue, and alpha values used by glClear to

clear the color buffers. Values specified by glClearColor are clamped to the range

[0 1].

GlMatrixMode ():sets the current matrix mode. mode can assume one of four values:

GL_MODELVIEW-Applies subsequent matrix operations to the modelview

matrix stack.

GL_PROJECTION-Applies subsequent matrix operations to the projection

matrix stack.

GluPerspective (): specifies a viewing frustum into the world coordinate system. In

general, the aspect ratio in gluPerspective should match the aspect ratio of the

associated viewport.

glDisable (): disable server-side GL capabilities.

glEnable ():enable server-side GL capabilities.

glutSolidTorus (): render a solid or wireframe torus (doughnut) respectively.

glutSolidCube (): render a solid or wireframe cube respectively.

glutSolidSphere (): Renders a sphere centered at the modeling coordinates origin of

the specified radius.

glutSolidIcosahedron (): This function draws a regular, solid 20-sided polyhedron

centered at the origin. The distance from the origin to the vertices is 1.

glutBitmapCharacter ():renders a bitmap character using OpenGL.

gluTessBeginContour():delimit the definition of a polygon contour. Within each

gluTessBeginContour /gluTessEndContourpair, there can be zero or more calls to

gluTessVertex. The vertices specify a closed contour (the last vertex of each contour is

automatically linked to the first.

glFeedbackBuffer():function controls feedback. Feedback, like selection, is an

OpenGL mode. The mode is selected by calling glRenderModewith

GL_FEEDBACK. When OpenGL is in feedback mode, no pixels are produced by

rasterization. Instead, information about primitives that would have been rasterized is

fed back to the application using OpenGL.

gluNewTess(): function creates and returns a pointer to a new tessellation object.

Refer to this object when calling tessellation functions. A return value of zero means

there is not enough memory to allocate to the object.


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GLU_TESS_BEGIN():The begin callback is invoked likeglBeginto indicate the start

of a (triangle) primitive. The function takes a single argument of type GLenum. If the

GLU_TESS_BOUNDARY_ONLYproperty is set to GL_FALSE, then the argument

is set to either GL_TRIANGLE_FAN, GL_TRIANGLE_STRIP, orGL_TRIANGLES. If the GLU_TESS_BOUNDARY_ONLYproperty is set to

GL_TRUE, then the argument will be set to GL_LINE_LOOP.

glLightfv():this function is used to set up the properties of proper light souce.

GLU_TESS_BOUNDARY_ONLY():Specifies a Boolean value (set value to

GL_TRUE or GL_FALSE). When you set value to GL_TRUE, a set of closed contours

separating the polygon interior and exterior is returned instead of a tessellation.

Exterior contours are oriented counterclockwise with respect to the normal; interior

contours are oriented clockwise. The GLU_TESS_BEGIN and

GLU_TESS_BEGIN_DATA callbacks use the type GL_LINE_LOOP for each

contour.
http://publib.boulder.ibm.com/infocenter/pseries/v5r3/topic/com.ibm.aix.opengl/doc/openglrf/glBegin.htm#b5ae449820vbiahttp://publib.boulder.ibm.com/infocenter/pseries/v5r3/topic/com.ibm.aix.opengl/doc/openglrf/glBegin.htm#b5ae449820vbiahttp://publib.boulder.ibm.com/infocenter/pseries/v5r3/topic/com.ibm.aix.opengl/doc/openglrf/glBegin.htm#b5ae449820vbiahttp://publib.boulder.ibm.com/infocenter/pseries/v5r3/topic/com.ibm.aix.opengl/doc/openglrf/glBegin.htm#b5ae449820vbia


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CHAPTER 5

TESTING

Testing in general means validation and verification. It shows that the system

conforms to its specifications and system meets all expectation of the user. It involves 5

different kind of testing.

5.1 TEST CASES FOR KEYBOARD:

Sl

No.

Test case

Description

Expected Result Actual Result Remarks

1. Press UP KEY Rotate the 3d object

In upward direction

Rotate the 3d object

In upward direction

PASS

2. Press DOWN

KEY


In left direction


In left direction

PASS

3. Press LEFT

key


In left direction


In left direction

PASS

4. Press Right

Key


In right direction


In right direction

PASS

Table1.1 test case for keyboard


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CHAPTER 6

6.1 SNAPSHOTS

Figure 1.5 Displaying menu when right clicked.


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Figure 1.6 3D view of cube


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The boundary of cube


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Figure 1.7 3D view of torus


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Figure 1.8 boundary of the torus.


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CHAPTER 7

CONCLUSION

The project BOUNDARY SIMULATION has many features in it which uses maximum

concepts provided in OpenGL such as lighting, shading, viewing, rendering etc. It has been

provided with simple interfaces so that the user can use it without the thorough knowledge of

OpenGL.

This is very reliable graphics package supporting various primitive objects like polygon,

line loops, etc. Also color selection, menu, keyboard based interface are included.


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CHAPTER 8

FUTURE ENHANCEMENTS

In this package we may consider the further enhancements like-

We can change the pattern some different textures.

Different colors can be implemented for the objects.

The objects size can be increased and decreased.

Add different types of lighting can be used.

Object can be moved in different directions

Different viewing can be used.


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CHAPTER 9

BIBLIOGRAPHY

Book References:[1] Edward AngelsInteractive Computer Graphics Pearson Edition 5th2007

[2] EditionM.Baumann OpenGL Programming with Glut. First Edition

[3] Yeshwant KanetkarComputer Graphics with C. Third Edition

Websites:

[4] http://www.opengl.org

[5]http://www.wikipedia.com

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