fix rhr (#81)

* fix rhr: no angles, just the cross-product

the old isRingClockwise as too fragile and came with too many
false negatives. use the established isRingClockwise algorithm.
bump version, fork to @rurban

* Updated CHANGELOG for 3.0.1

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 3.0.1
+
+* Fixed the rhr check (forked to @rurban)
+
 ## 3.0.0
 
 * Bump tested node versions to 8 & 10

lib/rhr.js

@@ -1,19 +1,15 @@
-function rad(x) {
-    return x * Math.PI / 180;
-}
-
 function isRingClockwise (coords) {
-    var area = 0;
+    var sum = 0;
     if (coords.length > 2) {
         var p1, p2;
         for (var i = 0; i < coords.length - 1; i++) {
             p1 = coords[i];
             p2 = coords[i + 1];
-            area += rad(p2[0] - p1[0]) * (2 + Math.sin(rad(p1[1])) + Math.sin(rad(p2[1])));
+            sum += (p2[0] - p1[0]) * (p2[1] + p1[1]);
         }
     }
 
-    return area >= 0;
+    return sum >= 0;
 }
 
 function isPolyRHR (coords) {

package.json

@@ -1,13 +1,13 @@
 {
-  "name": "@mapbox/geojsonhint",
+  "name": "@rurban/geojsonhint",
   "description": "validate and sanity-check geojson files",
-  "version": "3.0.0",
-  "author": "Tom MacWright",
+  "version": "3.0.1",
+  "author": "Reini Urban",
   "bin": {
     "geojsonhint": "./bin/geojsonhint"
   },
   "bugs": {
-    "url": "https://github.com/mapbox/geojsonhint/issues"
+    "url": "https://github.com/rurban/geojsonhint/issues"
   },
   "files": [
     "geojsonhint.js",
@@ -40,7 +40,7 @@
   "main": "lib/index.js",
   "repository": {
     "type": "git",
-    "url": "git://github.com/mapbox/geojsonhint.git"
+    "url": "git://github.com/rurban/geojsonhint.git"
   },
   "scripts": {
     "test": "eslint . && tap test/*.js --coverage",