ref: 3864ccc42aa08dba37937b280f7d814a786c5b31
dir: /sys/src/cmd/map/libmap/simpleconic.c/
#include <u.h> #include <libc.h> #include "map.h" static double r0, a; static int Xsimpleconic(struct place *place, double *x, double *y) { double r = r0 - place->nlat.l; double t = a*place->wlon.l; *x = -r*sin(t); *y = -r*cos(t); return 1; } proj simpleconic(double par0, double par1) { struct coord lat0; struct coord lat1; deg2rad(par0,&lat0); deg2rad(par1,&lat1); if(fabs(lat0.l+lat1.l)<.01) return rectangular(par0); if(fabs(lat0.l-lat1.l)<.01) { a = lat0.s/lat0.l; r0 = lat0.c/lat0.s + lat0.l; } else { a = (lat1.c-lat0.c)/(lat0.l-lat1.l); r0 = ((lat0.c+lat1.c)/a + lat1.l + lat0.l)/2; } return Xsimpleconic; }