Convert from xyz to lle as the main roam coordinates

[grits] / src / gis-util.c

diff --git a/src/gis-util.c b/src/gis-util.c
index 3bd5246002e134843c7c8c2a13726dbc8e05c653..19604feb35e21b6e0f917c42df607d4b964de5b0 100644 (file)
--- a/src/gis-util.c
+++ b/src/gis-util.c
@@ -65,3 +65,16 @@ gdouble distd(gdouble *a, gdouble *b)
                    (a[1]-b[1])*(a[1]-b[1]) +
                    (a[2]-b[2])*(a[2]-b[2]));
 }
+
+gdouble lon_avg(gdouble a, gdouble b)
+{
+       gdouble diff = ABS(a-b);
+       gdouble avg  = (a+b)/2;
+       if (diff > 180) {
+               if (avg >= 0)
+                       avg -= 180;
+               else
+                       avg += 180;
+       }
+       return avg;
+}