# Bresenham line drawing algorithm program in c

Here is the program Bresenham line drawing algorithm in C. This is Computer Graphics algorithm, Used to draw a line.

To draw a line using the Bresenham algorithm, C compiler uses Graphics.h header file. Here we will use Turbo C compiler to compile the program.

# include <stdio.h>
# include <conio.h>
# include <graphics.h>

void main()
{
int dx,dy,x,y,p,x1,y1,x2,y2;
int gd,gm;

clrscr();

printf("\n\n\tEnter the co-ordinates of first point : ");
scanf("%d %d",&x1,&y1);
printf("\n\n\tEnter the co-ordinates of second point : ");
scanf("%d %d",&x2,&y2);

dx = (x2 - x1);
dy = (y2 - y1);

p = 2 * (dy) - (dx);

x = x1;
y = y1;

detectgraph(&gd,&gm);
initgraph(&gd,&gm,"c:\\tc\\bgi");
putpixel(x,y,3);

while(x <= x2)
{
if(p < 0)
{
x=x+1;
y=y;
p = p + 2 * (dy);
}
else
{
x=x+1;
y=y+1;
p = p + 2 * (dy - dx);
}
putpixel(x,y,3);
}
getch();
closegraph();

}

1. algorithme 3D si possible

2. what does the variable "p" stand for?

1. Try to understand this..
http://www.tutorialspoint.com/computer_graphics/line_generation_algorithm.htm