Making a Compass point to a particular location in Unity

Question

I'm trying to make a compass that points to a custom location in a Unity program. However it's completely off, it points in generally the wrong direction and I can't quite seem to figure out what is wrong with my logic.

I'm using the curved geometry bearing equation from here: http://www.yourhomenow.com/house/haversine.html

1. Get current location.
2. Calculate bearing from current location to target location.

3. Rotate screen compass relative to true north.

   // Calculate bearing between current location and target location
   // Get current GPS location
   float lat1 = Input.location.lastData.latitude;
   float lon1 = Input.location.lastData.longitude;
   float lat2 = TargetLatitude;
   float dLon = TargetLongitude - lon1;
   
   // Calculate bearing
   var y = Mathf.Sin(dLon) * Mathf.Cos(lat2);
   var x = Mathf.Cos(lat1) * Mathf.Sin(lat2) -
           Mathf.Sin(lat1) * Mathf.Cos(lat2) * Mathf.Cos(dLon);
   var brng = ((Mathf.Atan2(y, x)*(180.0f/Mathf.PI)) + 360.0f) % 360.0f;
   
   Dump.text = brng.ToString();
   
   // Rotate the to target location relative to north. Z axis pointing out of screen.
   transform.eulerAngles = new Vector3(0, 0, Mathf.MoveTowardsAngle(transform.localEulerAngles.z, Input.compass.trueHeading + brng, COMPASS_MAXDELTA));
   

If I remove the bearing offset in that code, it points north enough for a digital compass.

Answer 1

Make sure that all of your angles are in radians rather than degrees.

Using Mathf.Deg2Rad in cases such as Mathf.Sin(dLon * Mathf.Deg2Rad) should yield the correct result. The Haversine formula only works for angles in radians.