#include "library.h"

const double pi = acos(-1.0),
             ang = atan(6.0),
             beta = pi/2 - ang,
             mul = sqrt(1 + 1.0/36);

double draw_dist(double len, double min)
{ if (len < min)
  { draw_distance(len);
    return len; }
  const double d1 = draw_dist(len/3, min);
  turn_left_by_radians(ang);
  const double d2 = draw_dist(mul * len/3, min);
  turn_right_by_radians(pi - 2 * beta);
  const double d3 = draw_dist(mul *len/3, min);
  turn_left_by_radians(ang);
  const double d4 = draw_dist(len/3, min);
  return d1 + d2 + d3 + d4; }

double draw_triangle(double side, double min)
{ const double d1 = draw_dist(side, min);
  turn_right_by_degrees(120);
  const double d2 = draw_dist(side, min);
  turn_right_by_degrees(120);
  const double d3 = draw_dist(side, min);
  turn_right_by_degrees(120);
  return d1 + d2 + d3; }

void main()
{ print("Minimum lines size? ");
  const double min = read_double();
  make_window(600, 600);
  move_to(100, 420);
  set_heading_degrees(30);
  const double p = draw_triangle(400, min);
  print("perimeter = ");
  print(p);
  new_line(); }