Clean up GPS display

[fw/altos] / aoview / aoview_state.c

diff --git a/aoview/aoview_state.c b/aoview/aoview_state.c
index 046ccc92ea5d982d77de2472b01c6493f74e7508..6530847ed98ed339a23de24329c96f169bb1c30f 100644 (file)
--- a/aoview/aoview_state.c
+++ b/aoview/aoview_state.c
@@ -45,16 +45,33 @@ aoview_great_circle (double start_lat, double start_lon,
 {
        double rad = M_PI / 180;
        double earth_radius = 6371.2;
-       double a = (90 - start_lat) * rad;
-       double b = (90 - end_lat) * rad;
-       double phi = (end_lon - start_lon) * rad;
-       double cosr = cos(a) * cos(b) + sin(a) * sin(b) * cos(phi);
-       double r = acos(cosr);
-       double rdist = earth_radius * r;
-       double sinth = sin(phi) * sin(b) / sin(r);
-       double th = asin(sinth) / rad;
-       *dist = rdist;
-       *bearing = th;
+       double lat1 = rad * start_lat;
+       double lon1 = -rad * start_lon;
+       double lat2 = rad * end_lat;
+       double lon2 = -rad * end_lon;
+
+       double d = acos(sin(lat1)*sin(lat2)+cos(lat1)*cos(lat2)*cos(lon1-lon2));
+       double argacos = (sin(lat2)-sin(lat1)*cos(d))/(sin(d)*cos(lat1));
+       double crs;
+       if (sin(lon2-lon1) < 0)
+               crs = acos(argacos);
+       else
+               crs = 2 * M_PI - acos(argacos);
+       *dist = d * earth_radius;
+       *bearing = crs * 180/M_PI;
+}
+
+static void
+aoview_state_add_deg(char *label, double deg)
+{
+       double  int_part;
+       double  min;
+
+       int_part = floor (deg);
+       min = (deg - int_part) * 60.0;
+       aoview_table_add_row(label, "%d°%lf'",
+                            (int) int_part, min);
+
 }
 
 void
@@ -112,8 +129,8 @@ aoview_state_notify(struct aostate *state)
        aoview_table_add_row("Pad altitude", "%dm", aoview_pres_to_altitude(pad_pres));
        aoview_table_add_row("Satellites", "%d", state->nsat);
        if (state->locked) {
-               aoview_table_add_row("Lat", "%g", state->lat);
-               aoview_table_add_row("Lon", "%g", state->lon);
+               aoview_state_add_deg("Latitude", state->lat);
+               aoview_state_add_deg("Longitude", state->lon);
                aoview_table_add_row("GPS alt", "%d", state->alt);
                aoview_table_add_row("GPS time", "%02d:%02d:%02d",
                                     state->gps_time.hour,
@@ -121,7 +138,8 @@ aoview_state_notify(struct aostate *state)
                                     state->gps_time.second);
                aoview_great_circle(pad_lat, pad_lon, state->lat, state->lon,
                                    &dist, &bearing);
-               aoview_table_add_row("Course", "%gkm %g°", dist, bearing);
+               aoview_table_add_row("Distance from pad", "%gm", dist * 1000);
+               aoview_table_add_row("Direction from pad", "%g°", bearing);
        } else {
                aoview_table_add_row("GPS", "unlocked");
        }