Program for line clipping usingCohen-Sutherland algorithm

//Program for line clipping usingCohen-Sutherland algorithm

#include

#include

#include

#define LEFT_EDGE 0x1

#define RIGHT_EDGE 0x2

#define BOTTOM_EDGE 0x4

#define TOP_EDGE 0x8

#define INSIDE(a) (!a)

#define REJECT(a,b) (a&b)

#define ACCEPT(a,b) (!(a|b))

#define FALSE 0

#define TRUE 1

#define ROUND(a) (int) (a+0.5)

typedef struct wcPt2{

float x,y;

};

typedef struct dcPt{

float x,y;

};

void swapPts(wcPt2*p1,wcPt2*p2)

{

wcPt2 tmp;

tmp=*p1;

*p1=*p2;

*p2=tmp;

}

unsigned char encode(wcPt2 pt, dcPt winMin,dcPt winMax)

{

unsigned char code=0x00;

if(pt.x

code=code|LEFT_EDGE;

if(pt.x>winMax.x)

code=code|RIGHT_EDGE;

if(pt.y

code=code|BOTTOM_EDGE;

if(pt.y>winMax.y)

code=code|TOP_EDGE;

return (code);

}

void swapCodes(unsigned char*c1,unsigned char*c2)

{

unsigned char tmp;

tmp=*c1;

*c1=*c2;

*c2=tmp;

}

void clipLine(dcPt winMin,dcPt winMax,wcPt2 p1,wcPt2 p2)

{

unsigned char code1,code2;

int done=FALSE, draw=FALSE;

float m;

while(!done)

{

code1=encode(p1,winMin,winMax);

code2=encode(p2,winMin,winMax);

if(ACCEPT(code1,code2))

{

done=TRUE;

draw=TRUE;

}

else if(REJECT(code1,code2))

done=TRUE;

else

{

if(INSIDE(code1))

{

swapPts(&p1,&p2);

swapCodes(&code1,&code2);

}

if(p2.x!=p1.x)

m=(p2.y-p1.y)/(p2.x-p1.x);

if(code1&LEFT_EDGE)

{

p1.y+=(winMin.x-p1.x)*m;

p1.x=winMin.x;

}

else if(code1&RIGHT_EDGE)

{

p1.y+=(winMax.x-p1.x)*m;

p1.x=winMax.x;

}

else if(code1&BOTTOM_EDGE)

{

if(p2.x!=p1.x)

p1.x+=(winMin.y-p1.y)/m;

p1.y=winMin.y;

}

else if(code1&TOP_EDGE)

{

if(p2.x!=p1.x)

p1.x+=(winMax.y-p1.y)/m;

p1.y=winMax.y;

}

}

}

cleardevice();

outtextxy(280,10,"AFTER CLIPPING");

rectangle(winMin.x,winMin.y,winMax.x,winMax.y);

line(ROUND(p1.x),ROUND(p1.y),ROUND(p2.x),ROUND(p2.y));

getch();

}

void main()

{

int gd=DETECT,gm;

wcPt2 p1,p2;

dcPt winMin,winMax;

printf("\nEnter Left-top corner coordinates of the window : ");

scanf("%f %f",&winMin.x,&winMin.y);

printf("Enter Right-bottom corner coordinates of the window : ");

scanf("%f %f",&winMax.x,&winMax.y);

printf("\nEnter coordinates of the line :-");

printf("\nFirst point : ");

scanf("%f %f",&p1.x,&p1.y);

printf("Second point : ");

scanf("%f %f",&p2.x,&p2.y);

initgraph(&gd,&gm,"e:\\tc\\bgi");

outtextxy(280,10,"BEFORE CLIPPING");

rectangle(winMin.x,winMin.y,winMax.x,winMax.y);

line(p1.x,p1.y,p2.x,p2.y);

getch();

cleardevice();

clipLine(winMin,winMax,p1,p2);

}