1. Graphics Programming in C
Kasun Ranga Wijeweera
(Email: krw19870829@gmail.com)

2. Evaluation Criteria
• Project: 40%
• End Semester Examination: 60%

3. Course Content
• Introduction to Graphics Programming in C
• Points, Lines and Polygons
• Line Drawing Algorithms
• Circle Drawing Algorithms
• Area Filling Algorithms
• Geometric Transformations in 2D
• Geometric Transformations in 3D
• Line Clipping Algorithms in 2D
• Line Clipping Algorithms in 3D

4. Integrated Development Environment
• Turbo C++ , Version 3.0, Copyright (c) 1990, 1992 by Borland
International, Inc

5. Graphics Header File
• Go to File  New
• Type initgraph in the new window and right click on it
• There you will find a program and using it lets try to create a
header file to initialize and exit graphics mode
• Open another file and save it as grap.h

6. The grap.h Header File
#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>
void ginit()
{
……
……
}
void gexit()
{
……
……
}

7. The ginit() Function
void ginit()
{
/* request auto detection */
int gdriver = DETECT, gmode, errorcode;
/* initialize graphics mode */
initgraph(&gdriver, &gmode, "D:/Tcpp/BGI");
/* read result of initialization */
errorcode = graphresult();
if (errorcode != grOk) /* an error occurred */
{
printf("Graphics error: %sn", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); /* return with error code */
}
}

8. The gexit() Function
void gexit()
{
closegraph();
}

9. The First Program
• Open a new file and save it as first.c
• There you have to include the grap.h header file that had been
created earlier
• Then your first program should look like as follows and
running it will give a black and empty screen
#include<stdio.h>
#include<conio.h>
#include"D:/GP/header/grap.h"
void main()
{
ginit();
getch();
gexit();
}

10. The Output Screen
• Execute following code to get the maximum x and maximum y
values of the output screen
#include<stdio.h>
#include<conio.h>
#include"D:/GP/header/grap.h"
void main()
{
ginit();
printf("%d %d",getmaxx(),getmaxy());
getch();
gexit();
}

11. The Output Screen
x
y

12. The Output Screen
• The y-axis is upside down?
• The solution:
(x,y)  (x, getmaxy() - y)
x
y
x
y

13. Better Approximation as an Integer
FLOOR (x + 0.5)

14. Approximating x and y Coordinates
int dpx(double x)
{
int p;
p=(int)(x+0.5);
return p;
}
int dpy(double y)
{
int p;
p=(int)(y+0.5);
p=getmaxy()-p;
return p;
}

15. Displaying a Point
void main()
{
ginit();
putpixel(dpx(50.2),dpy(70.7),15);
getch();
gexit();
}

16. Any Questions?

17. Thank You!