由不动点线性映射产生的分形3

#include "glib.h"
int N=12;     /*递归次数*/
double sx=120.0,sy=240.0;     /*开始点坐标*/
double leng0=400.0;     /*开始点与结束点的距离*/
double a,b,t=0.57735;

void fractal(double x0,double y0,double x1,double y1,int n)  /*分形图形描画函数*/
{
  double px,py;
  if (n<=N)
  {
 px=x0+(a*(x1-x0)-b*pow(-1.0,(double)n-1)*(y1-y0));
 py=y0+(b*pow(-1.0,(double)n-1)*(x1-x0)+a*(y1-y0));
 putpixel(px,-py,15);
 fractal(x0,y0,px,py,n+1);
 fractal(px,py,x1,y1,n+1);
  }
}

void main()
{
  ginit();
  set0(sx,sy);
  a=1.0/2;
  b=t/2;
  putpixel(0,0,9);         /*描画开始点*/
  putpixel(leng0,0,12);    /*描画结束点*/
  fractal(0.0,0.0,leng0,0.0,1);
  gend();
}