GPS Global Positioning System

GPS Script

The GPS script simulates a GPS device, providing a real world GPS coordinate relative to a GPSCoord object. The GPSCoord object simply must define these variables:

• easting
• northing
• zone
• lat
• lon

Easting and northing are used for UTM coordinates and lat/lon for NAD/WGS coordinates. This script can send the coordinates over a network through a Server.

Code

<javascript> using UnityEngine; using System.Collections;

public class GPS : MonoBehaviour { private GameObject gpsGO = null; private GPSCoord gpsRef = null; private double easting; private double northing; private int zone;

private double lat; private double lon; private ArrayList latlon_meters;

public double updateFreq = 1.0; private double timer = 0.0; private bool useLatLon = true;

// Use this for initialization void Start () { gpsGO = GameObject.Find("GPS Reference"); gpsRef = (GPSCoord)gpsGO.GetComponent("GPSCoord"); latlon_meters = FindMetersPerLat((float)gpsRef.lat); }

// Update is called once per frame void Update () { timer += Time.deltaTime;

easting = gpsRef.easting + gpsGO.transform.InverseTransformPoint(transform.position).x; //Calc current easting northing = gpsRef.northing + gpsGO.transform.InverseTransformPoint(transform.position).z; //Calc current northing

lat = gpsRef.lat + (gpsGO.transform.InverseTransformPoint(transform.position).z)/(double)latlon_meters[0]; //Calc current lat lon = gpsRef.lon + (gpsGO.transform.InverseTransformPoint(transform.position).x)/(double)latlon_meters[1]; //Calc current lon

latlon_meters = FindMetersPerLat((float)lat); //Update meters calc based on new coords

string sendString = ""; if(useLatLon==false) sendString += easting + "E " + northing + "N"; else sendString += string.Format("{0:0#.#####}N {1:0#.#####}W",lat,lon);

if(timer>(1.0/updateFreq)){ Send(sendString); timer=0; } // Debug.Log(sendString); }

void Send(string data){ if(Server.Connected()){ string sendString = gameObject.transform.root.name + "," + gameObject.name + "," + data + "\n"; Server.PutMessage(sendString); } }

//This function is a modified version of the JavaScript found at http://www.csgnetwork.com/degreelenllavcalc.html (C) CSGNetwork.COM and Computer Support Group

ArrayList FindMetersPerLat(float lat) // Compute lengths of degrees { // Set up "Constants" double m1 = 111132.92; // latitude calculation term 1 double m2 = -559.82; // latitude calculation term 2 double m3 = 1.175; // latitude calculation term 3 double m4 = -0.0023; // latitude calculation term 4 double p1 = 111412.84; // longitude calculation term 1 double p2 = -93.5; // longitude calculation term 2 double p3 = 0.118; // longitude calculation term 3 double latlen = 0.0; double lonlen = 0.0; // Convert latitude to radians

//lat = Mathf.Deg2Rad(lat); lat = (float)((lat*Mathf.PI)/180.0);

// Calculate the length of a degree of latitude and longitude in meters

latlen = m1 + (m2 * Mathf.Cos(2 * lat)) + (m3 * Mathf.Cos(4 * lat)) + (m4 * Mathf.Cos(6 * lat));

lonlen = (p1 * Mathf.Cos(lat)) + (p2 * Mathf.Cos(3 * lat)) + (p3 * Mathf.Cos(5 * lat));

ArrayList retval = new ArrayList(); retval.Add(latlen); retval.Add(lonlen);

return retval; }

} </javascript>