tbicentric.c - plan9port - [fork] Plan 9 from user space
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       ---
       tbicentric.c (437B)
       ---
            1 #include <u.h>
            2 #include <libc.h>
            3 #include "map.h"
            4 
            5 static struct coord center;
            6 
            7 static int
            8 Xbicentric(struct place *place, double *x, double *y)
            9 {
           10         if(place->wlon.c<=.01||place->nlat.c<=.01)
           11                 return(-1);
           12         *x = -center.c*place->wlon.s/place->wlon.c;
           13         *y = place->nlat.s/(place->nlat.c*place->wlon.c);
           14         return(*x**x+*y**y<=9);
           15 }
           16 
           17 proj
           18 bicentric(double l)
           19 {
           20         l = fabs(l);
           21         if(l>89)
           22                 return(0);
           23         deg2rad(l,&center);
           24         return(Xbicentric);
           25 }