BÀI TOÁN XÉN TỈA : Giải thuật Lyangbarsky

CODE

#include <conio.h>
#include <graphics.h>
#include <math.h>
#include <stdlib.h>
#include <iostream.h>
#define ROUND(a) ((double)(a+0.5)
#define TRUE 1
#define FALSE 0
int cliptest(double p, double q, double *u0, double *u1)
{
double r;
int retVal = TRUE;
if (p < 0.0)
{
r = q / p;
if (r > *u1)
retVal = FALSE;
else
if (r > *u0)
*u0 = r;
}
else
if ( p > 0.0)
{
r = q / p;
if (r < *u0)
retVal = FALSE;
else
if (r < *u1)
*u1 = r;
}
else{
if (q < 0.0)
retVal = FALSE;
}
return (retVal);
}


void clipline(double x1, double y1, double x2, double y2, double xmin, double ymin, double xmax, double ymax)
{
double u0 = 0.0, u1 = 1.0, dx, dy;
double oldx1, oldy1, oldx2, oldy2;
oldx1 = x1;
oldy1 = y1;
oldx2 = x2;
oldy2 = y2;
dx = x2 - x1;
if (cliptest(-dx, x1 - xmin, &u0, &u1))
if (cliptest(dx, xmax-x1, &u0, &u1))
{
dy = y2 - y1;
if (cliptest(-dy, y1 - ymin, &u0, &u1))
if (cliptest(dy, ymax - y1, &u0, &u1))
{
if (u1 < 1.0){
x2 = x1 + u1 * dx;
y2 = y1 + u1 * dy;
}
if (u0 > 0.0)
{
x1 += u0 * dx;
y1 += u0 * dy;
}
setcolor(RED);
line(oldx1, oldy1, x1, y1);
line(x2, y2, oldx2, oldy2);
setcolor(YELLOW);
line(x1, y1, x2, y2);
}
}
}
void main()
{
int gr_drive = DETECT, gr_mode;
double x1, y1, x2, y2, x3, y3, x4, y4;
initgraph(&gr_drive, &gr_mode, "../bgi");
cout<<"NHAP TOA DO DOAN THANG : \n";
cout<<"x1 = "; cin>>x1;
cout<<"y1 = "; cin>>y1;
cout<<"x2 = "; cin>>x2;
cout<<"y2 = "; cin>>y2;
cout<<"NHAP KHUNG WINDOW : ";
cout<<"x3 = "; cin>>x3;
cout<<"y3 = "; cin>>y3;
cout<<"x4 = "; cin>>x4;
cout<<"y4 = "; cin>>y4;
rectangle(x3,y3, x4, y4);
clipline(x1, y1, x2, y2,x3, y3, x4, y4);
getch();
closegraph();
}