diff options
Diffstat (limited to 'src/cmd/map/libmap/mercator.c')
-rw-r--r-- | src/cmd/map/libmap/mercator.c | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/src/cmd/map/libmap/mercator.c b/src/cmd/map/libmap/mercator.c new file mode 100644 index 00000000..0ab63653 --- /dev/null +++ b/src/cmd/map/libmap/mercator.c @@ -0,0 +1,36 @@ +#include <u.h> +#include <libc.h> +#include "map.h" + +static int +Xmercator(struct place *place, double *x, double *y) +{ + if(fabs(place->nlat.l) > 80.*RAD) + return(-1); + *x = -place->wlon.l; + *y = 0.5*log((1+place->nlat.s)/(1-place->nlat.s)); + return(1); +} + +proj +mercator(void) +{ + return(Xmercator); +} + +static double ecc = ECC; + +static int +Xspmercator(struct place *place, double *x, double *y) +{ + if(Xmercator(place,x,y) < 0) + return(-1); + *y += 0.5*ecc*log((1-ecc*place->nlat.s)/(1+ecc*place->nlat.s)); + return(1); +} + +proj +sp_mercator(void) +{ + return(Xspmercator); +} |