tconic.c - plan9port - [fork] Plan 9 from user space
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       ---
       tconic.c (496B)
       ---
            1 #include <u.h>
            2 #include <libc.h>
            3 #include "map.h"
            4 
            5 static struct coord stdpar;
            6 
            7 static int
            8 Xconic(struct place *place, double *x, double *y)
            9 {
           10         double r;
           11         if(fabs(place->nlat.l-stdpar.l) > 80.*RAD)
           12                 return(-1);
           13         r = stdpar.c/stdpar.s - tan(place->nlat.l - stdpar.l);
           14         *x = - r*sin(place->wlon.l * stdpar.s);
           15         *y = - r*cos(place->wlon.l * stdpar.s);
           16         if(r>3) return(0);
           17         return(1);
           18 }
           19 
           20 proj
           21 conic(double par)
           22 {
           23         if(fabs(par) <.1)
           24                 return(Xcylindrical);
           25         deg2rad(par, &stdpar);
           26         return(Xconic);
           27 }