This document provides an overview of graphics programming in C using Turbo C++. It outlines the course content which includes drawing points, lines, polygons, circles and filling areas. It also discusses geometric transformations in 2D and 3D as well as line clipping algorithms. It provides details on setting up the integrated development environment and creating a graphics header file to initialize and exit graphics mode. It includes code examples to display a single point on the screen by approximating pixel coordinates as integers.

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!