$/*$ Filename: SimplePaintProgram.cpp

Author: TMT$2033$ Introduction to Computer Graphics

Date: $6$ January $2010$

Description: This is a simple paint program that can draw lines and points. Upon

pressing the $\text{'}$c$\text{'}$ or $\text{'}$r$\text{'}$ key on the keyboard, the drawing area will clear. The program

will close when the $\text{'}$e$\text{'}$ key is pressed.

Modification Log: $-$

$*/$

#include

#include

#include

#define LINE $1$

#define POINT $2$

#define CLEAR $3$

$//$initialize global variables

int point$\_$size$=1$;

int line$\_$size$=1$;

int X$1=-1,$ X$2=-1,$ Y$1=-1,$ Y$2=-1$;

bool P$1=$ false, P$2=$false, P$3=$false, Cleared$=$false, Cleared$2=$false, Line$=$false, Point$=$false;

char $*$shape$="$No Shape Selected";

$//$this function draws the program's panels

void drawPanel$()$

$\{$

$//$panel backgound

glBegin$($GL$\_$QUADS$)$;

glColor$3$f$(1,0,1)$;

glVertex$2$i$(0,0)$;

glVertex$2$i$(0,60)$;

glVertex$2$i$(600,60)$;

glVertex$2$i$(600,0)$;

glEnd$()$;

$//$panel lines

glBegin$($GL$\_$LINES$)$;

glColor$3$f$(0,0,0)$;

glVertex$2$i$(0,60)$;

glVertex$2$i$(600,60)$;

glVertex$2$i$(0,30)$;

glVertex$2$i$(600,30)$;

glVertex$2$i$(120,60)$;

glVertex$2$i$(120,0)$;

glEnd$()$;

$//$this draws image of a point on its button

glBegin$($GL$\_$POINTS$)$;

glColor$3$f$(0,0,0)$;

glVertex$2$i$(61,45)$;

glVertex$2$i$(61,46)$;

glVertex$2$i$(60,45)$;

glVertex$2$i$(60,46)$;

glEnd$()$;

$//$this draws image of a line on its button

glBegin$($GL$\_$LINES$)$;

glColor$3$f$(0,0,0)$;

glVertex$2$i$(30,15)$;

glVertex$2$i$(90,15)$;

glEnd$()$;

$//$this displays the shape status on the panel

glColor$3$f$(0,0,0)$;

int tlength $=$ strlen$($shape$)$;

glRasterPos$3$f$(178,37,0)$;

for $($int counter$=0$; counter tlength; counter$++)\{$

glutBitmapCharacter$($GLUT$\_$BITMAP$\_$TIMES$\_$ROMAN$\_24,$ shape$[$counter$])$;

$\}$

$\}$

$//$this function draws points on the drawing area when the point button is selected

void drawPoint$()$

$\{$

if$($P$1==$true$)$

$\{$

glPointSize$($point$\_$size$)$; $//$set point size

glBegin$($GL$\_$POINTS$)$;

glColor$3$f$(0,0,0)$;

glVertex$2$i$($X$1,$Y$1)$;

glEnd$()$;

P$1=$false;

$\}$

$\}$

$//$this draws lines on the drawing area when the line button is selected

$//$a line is drawn by clicking twice on the drawing area

void drawLine$()$

$\{$

if$($P$1==$true && P$2==$true$)$

$\{$

glLineWidth$($line$\_$size$)$;

glBegin$($GL$\_$LINES$)$;

glColor$3$f$(0,0,0)$;

glVertex$2$i$($X$1,$Y$1)$;

glVertex$2$i$($X$2,$Y$2)$;

glEnd$()$;

P$1=$false;

P$2=$false;

$\}$

$\}$

$//$this is where all the calls to the functions are made

void draw$()$

$\{$

$//$the GL$\_$COLOR$\_$BUFFER$\_$BIT is cleared only once to keep the content of the drawing page

if$($Cleared $==$ false$)$

$\{$

glClear$($GL$\_$COLOR$\_$BUFFER$\_$BIT$)$;

Cleared $=$ true;

$\}$

$//$the drawPanel$()$ function is called everytime the draw function is called

drawPanel$()$;

$//$checks if the object is selected using the boolean, and calls the appropriate function

if $($Line$==$true$)$

drawLine$()$;

if $($Point$==$true$)$

drawPoint$()$;

glFlush$()$;

$\}$

$//$this function is responsible for the action that happens when we select from the menu panel

void processMenuEvents$($int option$)$

$\{$

if$($Cleared$2==$ false$)$

$\{$

glClear$($GL$\_$COLOR$\_$BUFFER$\_$BIT$)$;

Cleared$2=$ true;

$\}$

switch $($option$)$

$\{$

case LINE :

Line$=$ true;

Point$=$ false;

P$1=$false;P$2=$false;P$3=$false;

shape$=$"Drawing a Line";

break;

case POINT :

Line$=$ false;

Point$=$ true;

P$1=$false;P$2=$false;P$3=$false;

shape$=$"Drawing a Point";

break;

case CLEAR :

glClear$($GL$\_$COLOR$\_$BUFFER$\_$BIT$)$;

P$1=$ false,P$2=$false, P$3=$ false;

break;

$\}$

glutPostRedisplay$()$;

$\}$

$//$this function is responsible for mouse interaction

void mouse $($int btn$,$ int state, int x$,$ int y$)$

$\{$

$//$these are listeners for left mouse click events in the drawing area

if $($btn $==$ GLUT$\_$LEFT$\_$BUTTON && state $==$ GLUT$\_$DOWN && $600-$y $>60)$

$\{$

if $($Line$==$true$)$

$\{$

if$($P$1==$true && P$2==$false$)$

$\{$

X$2=$x;Y$2=600-$y;

P$2=$true;

$\}$

if$($P$1==$false$)$

$\{$

X$1=$x;Y$1=600-$y;

P$1=$true;

$\}$

$\}$

if $($Point$==$true$)$

$\{$

if$($P$1==$false$)$

$\{$

X$1=$x;Y$1=600-$y;

P$1=$true;

$\}$

$\}$

$\}$

$//$these are listeners for buttons in the panel

if$($ x $>0$ && x $<mtext></mtext><mn>1</mn><mn>2</mn><mn>0</mn>$ && $600-$y $>0$ && $600-$y $<mtext></mtext><mn>3</mn><mn>0</mn><mtext></mtext><mi>)</mi>$

processMenuEvents$($LINE$)$; $//$ line button

if$($ x $>0$ && x $<mtext></mtext><mn>1</mn><mn>2</mn><mn>0</mn>$ && $600-$y $>30$ && $600-$y $<mtext></mtext><mn>6</mn><mn>0</mn><mtext></mtext><mi>)</mi>$

processMenuEvents$($POINT$)$; $//$ point button

glutPostRedisplay$()$;

$\}$

$//$this function is responsible for creating a pop$-$up menu when the right mouse button is clicked

void createGLUTMenus$()$

$\{$

int menu;

menu $=$ glutCreateMenu$($processMenuEvents$)$;

glutAddMenuEntry$("$Clear$",$CLEAR$)$;

glutAttachMenu$($GLUT$\_$RIGHT$\_$BUTTON$)$;

$\}$

$//$this function is responsible for keyboard interaction

void keyboard $($unsigned char key, int x$,$ int y$)$

$\{$

switch$($key$)$

$\{$

case $99$:

glClear$($GL$\_$COLOR$\_$BUFFER$\_$BIT$)$;

break;

case $114$:

glClear$($GL$\_$COLOR$\_$BUFFER$\_$BIT$)$;

break;

case $101$:

exit$(0)$;

break;

$\}$

$\}$

$/*$ this is the main function where the toolkit is initialized, the display mode is set,

the window is created and the callback functions are registered. $*/$

void main$()$

$\{$

glutInitDisplayMode$($GLUT$\_$SINGLE $|$ GLUT$\_$RGB$)$;

glutInitWindowSize$(600,600)$;

glutInitWindowPosition$(20,20)$;

glutCreateWindow$("$Simple Paint Program for TMT$2033")$;

glutMouseFunc$($mouse$)$;

glutKeyboardFunc$($keyboard$)$;

glClearColor$(1,1,1,1)$;

glutDisplayFunc$($draw$)$;

glutIdleFunc$($draw$)$;

glOrtho$(0,600,0,600,0,1)$;

createGLUTMenus$()$;

glutMainLoop$()$;

$\}$