From 6eaf84d9e2180136f270205377f099dec041c5a1 Mon Sep 17 00:00:00 2001
From: ztimson <zaktimson@gmail.com>
Date: Fri, 30 Aug 2019 14:09:09 -0400
Subject: [PATCH] Added some new geo math utilities

---
 .../dimensionsDialog.component.ts             |  2 +-
 src/app/services/map.service.ts               |  4 +-
 src/app/utils.ts                              | 47 ++++++++++++++-----
 3 files changed, 38 insertions(+), 15 deletions(-)

diff --git a/src/app/components/dimensionsDialog/dimensionsDialog.component.ts b/src/app/components/dimensionsDialog/dimensionsDialog.component.ts
index 3c7771f..4941ee3 100644
--- a/src/app/components/dimensionsDialog/dimensionsDialog.component.ts
+++ b/src/app/components/dimensionsDialog/dimensionsDialog.component.ts
@@ -10,7 +10,7 @@ export class DimensionsDialogComponent {
     dimensionsOut: number[];
 
     constructor(private ref: MatDialogRef<DimensionsDialogComponent>, @Inject(MAT_DIALOG_DATA) public dimensions: string[]) {
-        this.dimensionsOut = Array(dimensions.length).fill(0);
+        this.dimensionsOut = Array(dimensions.length).fill(null);
     }
 
     close() {
diff --git a/src/app/services/map.service.ts b/src/app/services/map.service.ts
index dad7ce3..15ddd74 100644
--- a/src/app/services/map.service.ts
+++ b/src/app/services/map.service.ts
@@ -1,5 +1,5 @@
 import {BehaviorSubject} from "rxjs";
-import {distanceInM} from "../utils";
+import {latLngDistance} from "../utils";
 import {environment} from "../../environments/environment";
 import {Circle, LatLng, Marker, Measurement} from "../models/mapSymbol";
 
@@ -146,7 +146,7 @@ export class MapService {
         let group = L.layerGroup([line, decoration]).addTo(this.map);
         group.symbol = m;
         line.on('click', e => this.click.next({event: e, symbol: group}));
-        let distance = distanceInM(m.latlng.lat, m.latlng.lng, m.latlng2.lat, m.latlng2.lng);
+        let distance = latLngDistance(m.latlng, m.latlng2);
         line.bindPopup(`${distance > 1000 ? Math.round(distance / 100) / 10 : Math.round(distance)} ${distance > 1000 ? 'k' : ''}m`, {autoClose: false, closeOnClick: false}).openPopup();
         return group;
     }
diff --git a/src/app/utils.ts b/src/app/utils.ts
index b3014a9..cacc12f 100644
--- a/src/app/utils.ts
+++ b/src/app/utils.ts
@@ -1,3 +1,7 @@
+import {LatLng} from "./models/mapSymbol";
+
+export const R = 6_371; // Radius of the Earth
+
 export function copyToClipboard(value: string) {
     let el = document.createElement('textarea');
     el.value = value;
@@ -10,18 +14,37 @@ export function copyToClipboard(value: string) {
 }
 
 export function deg2rad(deg) {
-    return deg * (Math.PI/180);
+    return deg * Math.PI / 180;
 }
 
-export function distanceInM(lat1: number, lon1: number, lat2: number, lon2: number) {
-    const R = 6371; // Radius of the earth in km
-    let dLat = deg2rad(lat2-lat1);  // deg2rad below
-    let dLon = deg2rad(lon2-lon1);
-    let a =
-        Math.sin(dLat/2) * Math.sin(dLat/2) +
-        Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2)) *
-        Math.sin(dLon/2) * Math.sin(dLon/2)
-    ;
-    let c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
-    return R * c * 1000
+export function latLngBearing(latLng, latLng2) {
+    let dLng = (latLng2.lng - latLng.lng);
+    let y = Math.sin(dLng) * Math.cos(latLng2.lat);
+    let x = Math.cos(latLng.lat) * Math.sin(latLng2.lat) - Math.sin(latLng.lat) * Math.cos(latLng2.lat) * Math.cos(dLng);
+    return (360 - ((rad2deg(Math.atan2(y, x)) + 360) % 360));
+}
+
+export function latLngDistance(latLng, latLng2) {
+    let dLat = deg2rad(latLng2.lat - latLng.lat);
+    let dLng = deg2rad(latLng2.lng - latLng.lng);
+    let a = Math.sin(dLat/2) * Math.sin(dLat/2) + Math.cos(deg2rad(latLng.lat)) * Math.cos(deg2rad(latLng2.lat)) * Math.sin(dLng/2) * Math.sin(dLng/2);
+    return R * 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a)) * 1000
+}
+
+export function rad2deg(rad) {
+    return rad * 180 / Math.PI
+}
+
+export function relativeLatLng(latLng: LatLng, meters: number, deg: number) {
+    let brng = deg2rad(deg);
+    let d = meters / 1000;
+    let lat = deg2rad(latLng.lat);
+    let lng = deg2rad(latLng.lng);
+
+    let latOut = Math.asin(Math.sign(lat) * Math.cos(d / R) + Math.cos(lat) * Math.sin(d / R) * Math.cos(brng));
+    let lngOut = lng + Math.atan2(Math.sin(brng) * Math.sin(d / R) * Math.cos(lat), Math.cos(d / R) - Math.sin(lat) * Math.sin(latOut));
+    latOut = rad2deg(latOut);
+    lngOut = rad2deg(lngOut);
+
+    return {lat: latOut, lng: lngOut};
 }