- Chuong trinh ve duong cong Bezier */
#include <conio.h>
#include <dos.h>
#include <graphics.h>
#include "mouse.inc"
#define NPOINTS 8
struct xycoord {
double xcoord, ycoord;
};
/* Tra ve gia tri Factorial cua q (q!) */
double fact(int q)
{
int c;
double f = 1.0;
for (c=q; c>1; c--)
f *= (double)c;
return (f);
}
double C(int n, int i)
{
return (fact(n) / (fact(i) * fact(n-i)));
}
double blend(int i, int n, double u, double binomial)
{
double partial;
int j;
partial = binomial;
for (j=1; j<= i; j++)
partial *= u;
for (j=1; j<= (n-i); j++)
partial *= (1.0 - u);
return partial;
}
void BezierFcn (double *x, double *y, double u, double coeff[],
int n, struct xycoord p[])
{
int i;
double b;
*x = *y = 0;
for (i=0; i<=n; i++)
{
b = blend (i, n, u, coeff[i]);
*x += (b * p[i].xcoord);
*y += (b * p[i].ycoord);
}
}
void drawBezier(struct xycoord p[], int npts, int segments)
{
int i;
double u, x, y;
double coeff[20];
for (i=0; i<npts; i++)
coeff[i] = C(npts-1, i);
for (i=0; i<=segments; i++)
{
u = (double) i / segments;
BezierFcn(&x, &y, u, coeff, npts - 1, p);
if (i==0)
moveto(x, y);
else
lineto(x, y);
}
}
void main()
{
int gr_drive = DETECT, gr_mode, n, x, y;
unsigned char lbutton = 0, rbutton = 0;
struct xycoord pt[NPOINTS];
char s[50];
initgraph(&gr_drive, &gr_mode, "");
reset_mouse();
show_mouse();
setcolor(YELLOW);
rectangle(0, 0, getmaxx(), getmaxy());
sprintf(s, "Nhap nut trai chuot de chon toa do %d diem de ve", NPOINTS);
outtextxy(100, 10, s);
for (n=0; n<NPOINTS; n++)
{
do {
get_mouse_button(&lbutton, &rbutton, &x, &y);
} while (lbutton == 0 && rbutton == 0);
pt[n].xcoord = x;
pt[n].ycoord = y;
hide_mouse();
circle(x, y, 3);
show_mouse();
while (lbutton || rbutton)
get_mouse_button(&lbutton, &rbutton, &x, &y);
}
setcolor(RED);
hide_mouse();
moveto(pt[0].xcoord, pt[0].ycoord);
for (n=1; n<NPOINTS; n++)
lineto(pt[n].xcoord, pt[n].ycoord);
setcolor(YELLOW);
drawBezier(pt, NPOINTS, 40);
show_mouse();
getch();
closegraph();
}
Tiêu đề: Chuong trinh ve duong cong Bezier 
10/07/10, 09:54 pm