From 2a2f2ffef90b1a1d5f6fb709afd322e3cb7863e1 Mon Sep 17 00:00:00 2001
From: Joel Hulen <joelhulen@gmail.com>
Date: Sun, 21 Jan 2018 21:07:23 -0500
Subject: [PATCH 1/2] Improve gps location simulation

The previous version never actually changed the truck's location after the first pass. This version randomizes the changed distance, plus it adds a rounding function that handles the positive and negative values of the lat/long coordinates equally well. This results in an improved randomized route for the trucks. Not 100% realistic (data would need to be incorporated for that), but good enough for a simulation.
---
 .../devicemodels/scripts/truck-01-state.js    | 27 ++++++++++++++++---
 1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/Services/data/devicemodels/scripts/truck-01-state.js b/Services/data/devicemodels/scripts/truck-01-state.js
index c75828d1..69f50799 100644
--- a/Services/data/devicemodels/scripts/truck-01-state.js
+++ b/Services/data/devicemodels/scripts/truck-01-state.js
@@ -52,11 +52,29 @@ function varylocation(latitude, longitude, distance) {
     // Convert to meters, use Earth radius, convert to radians
     var radians = (distance * 1609.344 / 6378137) * (180 / Math.PI);
     return {
-        latitude: latitude + radians,
-        longitude: longitude + radians / Math.cos(latitude * Math.PI / 180)
+        latitude: roundTo((latitude + radians), 6),
+        longitude: roundTo((longitude + radians / Math.cos(latitude * Math.PI / 180)), 6)
     };
 }
 
+function roundTo(n, digits) {
+    var negative = false;
+    if (digits === undefined) {
+        digits = 0;
+    }
+    if (n < 0) {
+        negative = true;
+        n = n * -1;
+    }
+    var multiplicator = Math.pow(10, digits);
+    n = parseFloat((n * multiplicator).toFixed(11));
+    n = (Math.round(n) / multiplicator).toFixed(digits);
+    if (negative) {
+        n = (n * -1).toFixed(digits);
+    }
+    return n;
+}
+
 /**
  * Entry point function called by the simulation engine.
  *
@@ -70,8 +88,9 @@ function main(context, previousState) {
     // the telemetry can apply changes using the previous function state.
     restoreState(previousState);
 
-    // 0.1 miles around some location
-    var coords = varylocation(center_latitude, center_longitude, 0.1);
+    // Between -1.5 and 1.5 miles around start location
+    var distance = roundTo(vary(0.05, 2500, -1.5, 1.5), 2);
+    var coords = varylocation(center_latitude, center_longitude, distance);
     state.latitude = coords.latitude;
     state.longitude = coords.longitude;
 

From 7f8d8da331ea59c2c9ca6ae36692070f9178540b Mon Sep 17 00:00:00 2001
From: Joel Hulen <joelhulen@gmail.com>
Date: Sun, 21 Jan 2018 21:09:17 -0500
Subject: [PATCH 2/2] Improved gps location simulation

---
 .../devicemodels/scripts/truck-02-state.js    | 27 ++++++++++++++++---
 1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/Services/data/devicemodels/scripts/truck-02-state.js b/Services/data/devicemodels/scripts/truck-02-state.js
index 54eb2c48..7e26d70e 100644
--- a/Services/data/devicemodels/scripts/truck-02-state.js
+++ b/Services/data/devicemodels/scripts/truck-02-state.js
@@ -52,11 +52,29 @@ function varylocation(latitude, longitude, distance) {
     // Convert to meters, use Earth radius, convert to radians
     var radians = (distance * 1609.344 / 6378137) * (180 / Math.PI);
     return {
-        latitude: latitude + radians,
-        longitude: longitude + radians / Math.cos(latitude * Math.PI / 180)
+        latitude: roundTo((latitude + radians), 6),
+        longitude: roundTo((longitude + radians / Math.cos(latitude * Math.PI / 180)), 6)
     };
 }
 
+function roundTo(n, digits) {
+    var negative = false;
+    if (digits === undefined) {
+        digits = 0;
+    }
+    if (n < 0) {
+        negative = true;
+        n = n * -1;
+    }
+    var multiplicator = Math.pow(10, digits);
+    n = parseFloat((n * multiplicator).toFixed(11));
+    n = (Math.round(n) / multiplicator).toFixed(digits);
+    if (negative) {
+        n = (n * -1).toFixed(digits);
+    }
+    return n;
+}
+
 /**
  * Entry point function called by the simulation engine.
  *
@@ -70,8 +88,9 @@ function main(context, previousState) {
     // the telemetry can apply changes using the previous function state.
     restoreState(previousState);
 
-    // 0.1 miles around some location
-    var coords = varylocation(center_latitude, center_longitude, 0.1);
+    // Between -1.5 and 1.5 miles around start location
+    var distance = roundTo(vary(0.05, 2500, -1.5, 1.5), 2);
+    var coords = varylocation(center_latitude, center_longitude, distance);
     state.latitude = coords.latitude;
     state.longitude = coords.longitude;