自己写的三次Bezier曲线

#include "graphics.h"
 float px[4]={ 50,80,120,140 };
 float py[4]={100,230,230,160};
void Bezier()
{ 
float a0,a1,a2,a3,b0,b1,b2,b3;
int k,x,y;
float i,t,n=4;
setcolor(15);
for(k=0;k<3;k++)
{
moveto(px[k],py[k]);
lineto(px[k+1],py[k+1]);
}
setcolor(4);
        a0=px[0];
a1=-3*px[0]+3*px[1];
a2=3*px[0]-6*px[1]+3*px[2];
a3=-px[0]+3*px[1]-3*px[2]+px[3];
b0=py[0];
b1=-3*py[0]+3*py[1];
b2=3*py[0]-6*py[1]+3*py[2];
b3=-py[0]+3*py[1]-3*py[k+2]+py[3];
  for(i=0;i<n;i+=0.001)
   {
    t=i;
    x=a0+a1*t+a2*t*t+a3*t*t*t;
    y=b0+b1*t+b2*t*t+b3*t*t*t;
    if(i==0)moveto(x,y);
    lineto(x,y);