Program for Line Drawing using Bresenham’s algorithm

# include <iostream.h>

# include <conio.h>

# include <graphics.h>

# include <math.h>

char IncFlag;

void Bresenham(int x1,int x2,int y1,int y2);

void DrawLine(int X,int Y,int End,int PInc,int NInc,int P,int XInc,int YInc);

void main()

{

int gDriver=DETECT, gMode;

int x1,x2,y1,y2;

void Bresenham(int,int,int,int);

initgraph(&gDriver,&gMode,"c:\\tc\\bgi");

cout<<endl<<"x1 : ";

cin>>x1;

cout<<endl<<"y1 : ";

cin>>y1;

cout<<endl<<"x2 : ";

cin>>x2;

cout<<endl<<"y2 : ";

cin>>y2;

line(320,0,320,480);

line(0,240,640,240);

Bresenham(x1,x2,y1,y2);

getch();

}

void Bresenham(int x1,int x2,int y1,int y2)

{

int S,O,End;

int P;

int dx = abs(x1 - x2);

int dy = abs(y1 - y2);

float Slope;

int PInc,NInc,XInc,YInc;

if (dx == 0) //Slope Infinite

{

}

else

{

Slope = (float)(y1 - y2) / (x1 - x2);

if (Slope>-1 && Slope<1)

{

IncFlag = 'X';

PInc = 2 * (dy - dx);

NInc = 2 * dy;

P = 2 * dy - dx;

if (x1>x2)

{

S = x2;

O = y2;

End = x1;

}

else

{

S = x1;

O = y1;

End = x2;

}

// DrawLine(x,y,End,PInc,NInc,P,XInc,YInc);

}

else

{

IncFlag = 'Y';

PInc = 2 * (dx - dy);

NInc = 2 * dx;

P = 2 * dx - dy;

if (y1 > y2)

{

O = x2;

S = y2;

End = y1;

}

else

{

O = x1;

S = y1;

End = y2;

}

}

if (IncFlag == 'X')

putpixel(320+S,240-O,12);

else

putpixel(320+O,240-S,12);

while (S <= End)

{

S++;

if (P<0)

P = P + NInc;

else

{

P = P + PInc;

if (Slope>0.0)

O++;

else

O--;

}

if (IncFlag == 'X')

putpixel(320+S,240-O,12);

else

putpixel(320+O,240-S,12);

}

}

}

OUTPUT