/* Koch curve
 * E.Somfai, CO904 class, 2008-2011.
 */

#include <stdio.h>
#include <math.h>

#define MAX_ITER 6

#define C   cos(M_PI/3.)
#define S   sin(M_PI/3.)

void plot(double x1, double y1, double x2, double y2, int iter);

void
plot(double x1, double y1, double x2, double y2, int iter) {
	if (iter == 0) {
		printf("%lf %lf\n", x1, y1);
	} else {
		double dx = (x2-x1)/3;		// 1/3 vector
		double dy = (y2-y1)/3;
		double xx = C * dx - S * dy;	// rotated 1/3 vector
		double yy = S * dx + C * dy;

		plot(x1,       y1,       x1+dx,    y1+dy,    iter-1);
		plot(x1+dx,    y1+dy,    x1+dx+xx, y1+dy+yy, iter-1);
		plot(x1+dx+xx, y1+dy+yy, x1+2*dx,  y1+2*dy,  iter-1);
		plot(x1+2*dx,  y1+2*dy,  x2,       y2,       iter-1);
	}
}

int main()
{
	plot(0., 0., 1., 0., MAX_ITER);	
	plot(1., 0., C,  -S, MAX_ITER);	// two more starting lines
	plot(C,  -S, 0., 0., MAX_ITER);	// to complete the init. triangle
	return 0;
}