plan9port

fork of plan9port with libvec, libstr and libsdb
Log | Files | Refs | README | LICENSE

fisheye.c (407B)

      1 #include <u.h>
      2 #include <libc.h>
      3 #include "map.h"
      4 /* refractive fisheye, not logarithmic */
      5 
      6 static double n;
      7 
      8 static int
      9 Xfisheye(struct place *place, double *x, double *y)
     10 {
     11 	double r;
     12 	double u = sin(PI/4-place->nlat.l/2)/n;
     13 	if(fabs(u) > .97)
     14 		return -1;
     15 	r = tan(asin(u));
     16 	*x = -r*place->wlon.s;
     17 	*y = -r*place->wlon.c;
     18 	return 1;
     19 }
     20 
     21 proj
     22 fisheye(double par)
     23 {
     24 	n = par;
     25 	return n<.1? 0: Xfisheye;
     26 }