GPS 2D compass to point to Longitude and Latitude

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Hello everyone, I want to ask you about something. I have this project that is required to use the GPS coordinates from the phone and the direction to implement a compass to point to other fixed coordinates.

I have searched for a while and the closest I got to what I need was this link: https://stackoverflow.com/questions/23207486/making-a-compass-point-to-a-particular-location-in-unity

I'm won't say I understand the equation mentioned in the link but all it did was make the object point downwards no matter where I'm or how the phone is oriented.

Can someone guide me through this or point me to a tutorial on how to implement such feature?

Thank you.

[Edit] I have found a website explaining an equation that would calculate the bearing and the distance between two points but I'm still struggling with adding it to my scripts https://www.movable-type.co.uk/scripts/latlong.html

Answer 1

Best Answer

Answer by ibrahimAlfors · May 02, 2018 at 10:29 PM

I was able to find a solution for those who want to use it, I used this link https://stackoverflow.com/questions/3932502/calculate-angle-between-two-latitude-longitude-points

here is my code

 private float angleFromCoordinate(float lat1, float long1, float lat2, float long2) {
         lat1 *= Mathf.Deg2Rad;
         lat2 *= Mathf.Deg2Rad;
         long1 *= Mathf.Deg2Rad;
         long2 *= Mathf.Deg2Rad;
 
         float dLon = (long2 - long1);
         float y = Mathf.Sin(dLon) * Mathf.Cos(lat2); 
         float x = (Mathf.Cos(lat1) * Mathf.Sin(lat2)) - (Mathf.Sin(lat1) * Mathf.Cos(lat2) * Mathf.Cos(dLon));
         float brng = Mathf.Atan2(y, x); 
         brng = Mathf.Rad2Deg* brng; 
         brng = (brng + 360) % 360; 
         brng = 360 - brng;
         return brng;
     }

and to use it, in the Update Method:

 float bearing = angleFromCoordinate(current.latitude,current.longitude,
             destination.latitude,destination.longitude);
         
         compass.rotation = Quaternion.Slerp(compass.rotation, Quaternion.Euler(0, 0, Input.compass.magneticHeading + bearing), 100f);

I hope this help you guys.

Thanks.

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ibrahimAlfors · May 02, 2018 at 10:30 PM 0

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One strange thing thou, if you flip your phone on its screen, it also flips the compass and makes the bearing inverted. Not sure how to fix that thou.

Eeyung · Oct 12, 2018 at 04:40 AM 0

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Hi, may i know how to apply it to a gameobject? let's say i want an arrow(game object) always point to the destination coordinate during runtime, it is allow to apply it to a game object?

ibrahim2unityfocus Eeyung · Oct 13, 2018 at 11:59 AM 0

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Hello, Well, as you see in the answer all you need is to create the method angleFromCoordinate and use the other code snippet in the update method. You will need to enable the GPS. After that, just drag and drop the script on the object and it should work.

ABHINAVSAHA_- · Oct 17, 2020 at 07:54 PM 0

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The script doesn't seems to be working for me. The compass rotates a bit and doesn't rotates any further. It doesn't rotates when I rotate my phone

GPS 2D compass to point to Longitude and Latitude

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