ref: c3ba64f6935322f09b6de5c2285544fd471c605d
dir: /sys/src/cmd/map/route.c/
#include <u.h>
#include <libc.h>
#include "map.h"
/* Given two lat-lon pairs, find an orientation for the
-o option of "map" that will place those two points
on the equator of a standard projection, equally spaced
about the prime meridian.
-w and -l options are suggested also.
Option -t prints out a series of
coordinates that follows the (great circle) track
in the original coordinate system,
followed by ".
This data is just right for map -t.
Option -i inverts the map top-to-bottom.
*/
struct place pole;
struct coord twist;
int track;
int inv = -1;
extern void doroute(double, double, double, double, double);
void
dorot(double a, double b, double *x, double *y, void (*f)(struct place *))
{
struct place g;
deg2rad(a,&g.nlat);
deg2rad(b,&g.wlon);
(*f)(&g);
*x = g.nlat.l/RAD;
*y = g.wlon.l/RAD;
}
void
rotate(double a, double b, double *x, double *y)
{
dorot(a,b,x,y,normalize);
}
void
rinvert(double a, double b, double *x, double *y)
{
dorot(a,b,x,y,invert);
}
main(int argc, char **argv)
{
#pragma ref argv
double an,aw,bn,bw;
ARGBEGIN {
case 't':
track = 1;
break;
case 'i':
inv = 1;
break;
default:
exits("route: bad option");
} ARGEND;
if (argc<4) {
print("use route [-t] [-i] lat lon lat lon\n");
exits("arg count");
}
an = atof(argv[0]);
aw = atof(argv[1]);
bn = atof(argv[2]);
bw = atof(argv[3]);
doroute(inv*90.,an,aw,bn,bw);
return 0;
}
void
doroute(double dir, double an, double aw, double bn, double bw)
{
double an1,aw1,bn1,bw1,pn,pw;
double theta;
double cn,cw,cn1,cw1;
int i,n;
orient(an,aw,0.);
rotate(bn,bw,&bn1,&bw1);
/* printf("b %f %f\n",bn1,bw1);*/
orient(an,aw,bw1);
rinvert(0.,dir,&pn,&pw);
/* printf("p %f %f\n",pn,pw);*/
orient(pn,pw,0.);
rotate(an,aw,&an1,&aw1);
rotate(bn,bw,&bn1,&bw1);
theta = (aw1+bw1)/2;
/* printf("a %f %f \n",an1,aw1);*/
orient(pn,pw,theta);
rotate(an,aw,&an1,&aw1);
rotate(bn,bw,&bn1,&bw1);
if(fabs(aw1-bw1)>180)
if(theta<0.) theta+=180;
else theta -= 180;
orient(pn,pw,theta);
rotate(an,aw,&an1,&aw1);
rotate(bn,bw,&bn1,&bw1);
if(!track) {
double dlat, dlon, t;
/* printf("A %.4f %.4f\n",an1,aw1); */
/* printf("B %.4f %.4f\n",bn1,bw1); */
cw1 = fabs(bw1-aw1); /* angular difference for map margins */
/* while (aw<0.0)
aw += 360.;
while (bw<0.0)
bw += 360.; */
dlon = fabs(aw-bw);
if (dlon>180)
dlon = 360-dlon;
dlat = fabs(an-bn);
printf("-o %.4f %.4f %.4f -w %.2f %.2f %.2f %.2f \n",
pn,pw,theta, -0.3*cw1, .3*cw1, -.6*cw1, .6*cw1);
} else {
cn1 = 0;
n = 1 + fabs(bw1-aw1)/.2;
for(i=0;i<=n;i++) {
cw1 = aw1 + i*(bw1-aw1)/n;
rinvert(cn1,cw1,&cn,&cw);
printf("%f %f\n",cn,cw);
}
printf("\"\n");
}
}