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Sourcecode: r-cran-mapproj version File versions  Download package

fisheye.c

/* RSB #include <u.h>
#include <libc.h>*/
#include "map.h"
/* refractive fisheye, not logarithmic */

static double n;

static int
Xfisheye(struct place *place, double *x, double *y)
{
      double r;
      double u = sin(PI/4-place->nlat.l/2)/n;
      if(fabs(u) > .97)
            return -1;
      r = tan(asin(u));
      *x = -r*place->wlon.s;
      *y = -r*place->wlon.c;
      return 1;
}

proj
fisheye(double par)
{
      n = par;
      return n<.1? 0: Xfisheye;
}

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