Merge pull request #6078 from bjornharrtell/windingnumber

Use winding number algorithm for linearRingContainsXY

src/ol/geom/flat/contains.js

@@ -36,22 +36,30 @@ ol.geom.flat.contains.linearRingContainsExtent = function(flatCoordinates, offse
  * @return {boolean} Contains (x, y).
  */
 ol.geom.flat.contains.linearRingContainsXY = function(flatCoordinates, offset, end, stride, x, y) {
-  // http://www.ecse.rpi.edu/Homepages/wrf/Research/Short_Notes/pnpoly.html
+  // http://geomalgorithms.com/a03-_inclusion.html
-  var contains = false;
+  // Copyright 2000 softSurfer, 2012 Dan Sunday
+  // This code may be freely used and modified for any purpose
+  // providing that this copyright notice is included with it.
+  // SoftSurfer makes no warranty for this code, and cannot be held
+  // liable for any real or imagined damage resulting from its use.
+  // Users of this code must verify correctness for their application.
+  var wn = 0;
   var x1 = flatCoordinates[end - stride];
   var y1 = flatCoordinates[end - stride + 1];
   for (; offset < end; offset += stride) {
     var x2 = flatCoordinates[offset];
     var y2 = flatCoordinates[offset + 1];
-    var intersect = ((y1 > y) != (y2 > y)) &&
+    if (y1 <= y) {
-        (x < (x2 - x1) * (y - y1) / (y2 - y1) + x1);
+      if (y2 > y && ((x2 - x1) * (y - y1)) - ((x - x1) * (y2 - y1)) > 0) {
-    if (intersect) {
+        wn++;
-      contains = !contains;
+      }
+    } else if (y2 <= y && ((x2 - x1) * (y - y1)) - ((x - x1) * (y2 - y1)) < 0) {
+      wn--;
     }
     x1 = x2;
     y1 = y2;
   }
-  return contains;
+  return wn !== 0;
 };
 
 

test/spec/ol/geom/flat/contains.test.js

@@ -0,0 +1,42 @@
+goog.provide('ol.test.geom.flat.contains');
+
+goog.require('ol.geom.flat.contains');
+
+
+describe('ol.geom.flat.contains', function() {
+
+  describe('with simple data', function() {
+
+    var flatCoordinatesSimple = [0, 0, 1, 0, 1, 1, 0, 1];
+    var flatCoordinatesNonSimple = [0, 0, 4, 0, 4, 3, 1, 3, 1, 2, 3, 2, 3, 1, 2, 1, 2, 4, 0, 4];
+
+    describe('ol.geom.flat.contains.linearRingContainsXY', function() {
+
+      it('returns true for point inside a simple polygon', function() {
+        expect(ol.geom.flat.contains.linearRingContainsXY(
+            flatCoordinatesSimple, 0, flatCoordinatesSimple.length, 2, 0.5, 0.5)).to.be(true);
+      });
+
+      it('returns false for point outside a simple polygon', function() {
+        expect(ol.geom.flat.contains.linearRingContainsXY(
+            flatCoordinatesSimple, 0, flatCoordinatesSimple.length, 2, 1.5, 1.5)).to.be(false);
+      });
+
+      it('returns true for point inside a non-simple polygon', function() {
+        expect(ol.geom.flat.contains.linearRingContainsXY(
+            flatCoordinatesNonSimple, 0, flatCoordinatesNonSimple.length, 2, 1, 1)).to.be(true);
+      });
+
+      it('returns true for point inside an overlap of a non-simple polygon', function() {
+        expect(ol.geom.flat.contains.linearRingContainsXY(
+            flatCoordinatesNonSimple, 0, flatCoordinatesNonSimple.length, 2, 1.5, 2.5)).to.be(true);
+      });
+
+      it('returns false for a point inside a hole of a non-simple polygon', function() {
+        expect(ol.geom.flat.contains.linearRingContainsXY(
+            flatCoordinatesNonSimple, 0, flatCoordinatesNonSimple.length, 2, 2.5, 1.5)).to.be(false);
+      });
+
+    });
+  });
+});