fix: prevent getDistanceFromLine to return NaN due to floating point …

…arithmetic. fixes #227

src/getDistance.ts

@@ -1,19 +1,10 @@
 import getLatitude from './getLatitude';
 import getLongitude from './getLongitude';
 import toRad from './toRad';
+import robustAcos from './robustAcos';
 import { earthRadius } from './constants';
 import { GeolibInputCoordinates } from './types';
 
-const normalizeACosArg = (val: number): number => {
-    if (val > 1) {
-        return 1;
-    }
-    if (val < -1) {
-        return -1;
-    }
-    return val;
-};
-
 // Calculates the distance between two points.
 // This method is simple but also more inaccurate
 const getDistance = (
@@ -31,7 +22,7 @@ const getDistance = (
 
     const distance =
         Math.acos(
-            normalizeACosArg(
+            robustAcos(
                 Math.sin(toRad(toLat)) * Math.sin(toRad(fromLat)) +
                     Math.cos(toRad(toLat)) *
                         Math.cos(toRad(fromLat)) *

src/getDistanceFromLine.test.js

@@ -10,4 +10,23 @@ describe('getDistanceFromLine', () => {
             )
         ).toEqual(188.5131192933101);
     });
+
+    it('should not break if line start and line end are too close', () => {
+        const point = {
+            longitude: -75.63287336843746,
+            latitude: 6.278381350919607,
+        };
+
+        const lineStart = {
+            longitude: -75.6220658304469,
+            latitude: 6.285304104233529,
+        };
+
+        const lineEnd = {
+            longitude: -75.62216373107594,
+            latitude: 6.285232119894652,
+        };
+
+        expect(getDistanceFromLine(point, lineStart, lineEnd)).toEqual(1409);
+    });
 });

src/getDistanceFromLine.ts

@@ -1,4 +1,5 @@
 import getDistance from './getDistance';
+import robustAcos from './robustAcos';
 import { GeolibInputCoordinates } from './types';
 
 // Returns the minimum distance from a point to a line
@@ -12,10 +13,14 @@ const getDistanceFromLine = (
     const d3 = getDistance(lineStart, lineEnd);
 
     // alpha is the angle between the line from start to point, and from start to end
-    const alpha = Math.acos((d1 * d1 + d3 * d3 - d2 * d2) / (2 * d1 * d3));
+    const alpha = Math.acos(
+        robustAcos((d1 * d1 + d3 * d3 - d2 * d2) / (2 * d1 * d3))
+    );
 
     // beta is the angle between the line from end to point and from end to start //
-    const beta = Math.acos((d2 * d2 + d3 * d3 - d1 * d1) / (2 * d2 * d3));
+    const beta = Math.acos(
+        robustAcos((d2 * d2 + d3 * d3 - d1 * d1) / (2 * d2 * d3))
+    );
 
     // if the angle is greater than 90 degrees, then the minimum distance is the
     // line from the start to the point