How to find the degree of rotation for marker on map while using react-native-maps with google maps api?

Question

I am trying to make an uber like app using react-native. I am using react-native-maps. I have successfully mapped the directions using directions api of google maps, and I have been able to move my car marker on the path successfully, but the problem is the direction of the car. I want to change the direction of the car as the direction of the road changes. I have been trying to find a way to do it for a long time, but I have found nothing. If anyone can help, that will be much appreciated.

Answer 1

You can find the the degree of rotation between two coordinates by using the following function

const calculateHeading = (cord1, cord2) => {
    if (cord2) {
      const {latitude: lat1, longitude: lng1} = cord1;
      const {latitude: lat2, longitude: lng2} = cord2;
      const y = Math.sin(lng2 - lng1) * Math.cos(lat2);
      const x =
        Math.cos(lat1) * Math.sin(lat2) -
        Math.sin(lat1) * Math.cos(lat2) * Math.cos(lng2 - lng1);
      const ? = Math.atan2(y, x);
      const brng = ((? * 180) / Math.PI + 360) % 360;
      return brng;
    }
    return 0;
  };