AP_Common: move location_update to Location and rename to offset_bearing

libraries/AP_Common/Location.cpp

@@ -232,6 +232,20 @@ void Location::offset(float ofs_north, float ofs_east)
     }
 }
 
+/*
+ *  extrapolate latitude/longitude given bearing and distance
+ * Note that this function is accurate to about 1mm at a distance of
+ * 100m. This function has the advantage that it works in relative
+ * positions, so it keeps the accuracy even when dealing with small
+ * distances and floating point numbers
+ */
+void Location::offset_bearing(float bearing, float distance)
+{
+    const float ofs_north = cosf(radians(bearing)) * distance;
+    const float ofs_east  = sinf(radians(bearing)) * distance;
+    offset(ofs_north, ofs_east);
+}
+
 float Location::longitude_scale() const
 {
     float scale = cosf(lat * (1.0e-7f * DEG_TO_RAD));

libraries/AP_Common/Location.h

@@ -75,6 +75,9 @@ public:
     // extrapolate latitude/longitude given distances (in meters) north and east
     void offset(float ofs_north, float ofs_east);
 
+    // extrapolate latitude/longitude given bearing and distance
+    void offset_bearing(float bearing, float distance);
+
     // longitude_scale - returns the scaler to compensate for
     // shrinking longitude as you move north or south from the equator
     // Note: this does not include the scaling to convert