Data commit

Task/Ray-casting-algorithm/JavaScript/ray-casting-algorithm.js

@@ -0,0 +1,58 @@
+/**
+ * @return {boolean} true if (lng, lat) is in bounds
+ */
+function contains(bounds, lat, lng) {
+    //https://rosettacode.org/wiki/Ray-casting_algorithm
+    var count = 0;
+    for (var b = 0; b < bounds.length; b++) {
+        var vertex1 = bounds[b];
+        var vertex2 = bounds[(b + 1) % bounds.length];
+        if (west(vertex1, vertex2, lng, lat))
+            ++count;
+    }
+    return count % 2;
+
+    /**
+     * @return {boolean} true if (x,y) is west of the line segment connecting A and B
+     */
+    function west(A, B, x, y) {
+        if (A.y <= B.y) {
+            if (y <= A.y || y > B.y ||
+                x >= A.x && x >= B.x) {
+                return false;
+            } else if (x < A.x && x < B.x) {
+                return true;
+            } else {
+                return (y - A.y) / (x - A.x) > (B.y - A.y) / (B.x - A.x);
+            }
+        } else {
+            return west(B, A, x, y);
+        }
+    }
+}
+
+var square = {name: 'square', bounds: [{x: 0, y: 0}, {x: 20, y: 0}, {x: 20, y: 20}, {x: 0, y: 20}]};
+var squareHole = {
+    name: 'squareHole',
+    bounds: [{x: 0, y: 0}, {x: 20, y: 0}, {x: 20, y: 20}, {x: 0, y: 20}, {x: 5, y: 5}, {x: 15, y: 5}, {x: 15, y: 15}, {x: 5, y: 15}]
+};
+var strange = {
+    name: 'strange',
+    bounds: [{x: 0, y: 0}, {x: 5, y: 5}, {x: 0, y: 20}, {x: 5, y: 15}, {x: 15, y: 15}, {x: 20, y: 20}, {x: 20, y: 0}]
+};
+var hexagon = {
+    name: 'hexagon',
+    bounds: [{x: 6, y: 0}, {x: 14, y: 0}, {x: 20, y: 10}, {x: 14, y: 20}, {x: 6, y: 20}, {x: 0, y: 10}]
+};
+
+var shapes = [square, squareHole, strange, hexagon];
+var testPoints = [{lng: 10, lat: 10}, {lng: 10, lat: 16}, {lng: -20, lat: 10},
+    {lng: 0, lat: 10}, {lng: 20, lat: 10}, {lng: 16, lat: 10}, {lng: 20, lat: 20}];
+
+for (var s = 0; s < shapes.length; s++) {
+    var shape = shapes[s];
+    for (var tp = 0; tp < testPoints.length; tp++) {
+        var testPoint = testPoints[tp];
+        console.log(JSON.stringify(testPoint) + '\tin ' + shape.name + '\t' + contains(shape.bounds, testPoint.lat, testPoint.lng));
+    }
+}