kochfract

#include <stdio.h>
#include <math.h>
/* Generate koch fractal in SVG format (Scalable vector graphics)
 * http://ecademy.agnesscott.edu/~lriddle/ifs/kcurve/kcurve.htm
 * Run ./a.out > kochfract.svg and look at the file in a browser
 * SVG drawing commands: l=line, m=move, h=horiz. line, v=vert. line
 * uppercase: absolute coordinates, lowercase: relative coordinates
 * e.g. M x y = move to (x, y)
 * l dx dy = line from current point, moving by dx, dy */
void kochfract(double len, double ang) {
    if (len < 30) {
    printf("l %.1f %.1f ", len * cos(ang), -len * sin(ang));
}
    else {
    double l3 = len/3;
    kochfract(l3, ang);
    kochfract(l3, ang+acos(.5));
    kochfract(l3, ang-acos(.5));
    kochfract(l3, ang);
}
}
int main(void)
{
  printf("%s", "<?xml version=\"1.0\"?>\n"  // .svg file header
       "<svg version=\"1.1\" xmlns=\"http://www.w3.org/2000/svg\">\n"
       "<path fill=\"none\" stroke=\"blue\" d=\"M 0 200 ");
  kochfract(300, 0);
  puts("\"/>\n</svg>");             // end of .svg file
  return 0;
}