LINE CLIPPING USING LIANG BARSKY ALGORITHM

LINE CLIPPING USING LIANG BARSKY ALGORITHM

#include<stdio.h>

#include<conio.h>

#include<graphics.h>

#include<dos.h>

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

int cliptest(float p,float q,float *u1,float *u2)

{

            float r;

            int retval=1;

            if(p<0.0)

            {

                        r=q/p;

                        if(r>*u2)

                                    retval=0;

                        if(r>*u1)

                                    *u1=r;

            }

            else if(p>0.0)

            {

                        r=q/p;

                        if(r<*u1)

                                    retval=0;

                        if(r<*u2)

                                    *u2=r;

            }

            else if(q<0.0)

                        retval=0;

            return(retval);

}

void clipline(int minx,int miny,int maxx,int maxy,int x1,int y1,int x2,int y2)

{

            float u1=0.0,u2=1.0,dx=x2-x1,dy;

            if(cliptest(-dx,x1-minx,&u1,&u2))

                        if(cliptest(dx,maxx-x1,&u1,&u2))

                        {

                                    dy=y2-y1;

                                    if(cliptest(-dy,y1-miny,&u1,&u2))

                                                if(cliptest(dy,maxy-y1,&u1,&u2))

                                                {

                                                            if(u2<1.0)

                                                            {

                                                                        x2=x1+u2*dx;

                                                                        y2=y1+u2*dy;

                                                            }

                                                            if(u1>0.0)

                                                            {

                                                                        x1+=u1*dx;

                                                                        y1+=u1*dy;

                                                            }

                                                            line(x1,y1,x2,y2);

                                                }

                        }

}

void main()

{

            int gdriver=DETECT,gmode,x1,y1,x2,y2,minx,miny,maxx,maxy;

            initgraph(&gdriver,&gmode,"");

            clrscr();

            printf("Enter the min & max x values: ");

            scanf("%d %d",&minx,&maxx);

            printf("Enter the min & max y values: ");

            scanf("%d %d",&miny,&maxy);

            printf("Enter the first endpoint: ");

            scanf("%d %d",&x1,&y1);

            printf("Enter the second endpoint: ");

            scanf("%d %d",&x2,&y2);

            clrscr();

            printf("Before Clipping");

            line(x1,y1,x2,y2);

            rectangle(minx,maxy,maxx,miny);

            getch();

            clrscr();

            printf("After Clipping");

            clipline(minx,miny,maxx,maxy,x1,y1,x2,y2);

            rectangle(minx,maxy,maxx,miny);

            getch();

}

OUTPUT:-

            Enter the min & max x values:: 300  400

            Enter the min & max x values:: 300  400

            Enter the first endpoint  : 275  300

            Enter the second endpoint : 350  420

            Before Clipping

           

                                                                               

 After Clipping