Geom.Intersects.GetRaysFromPointToPolygon is a new function that emits rays out from the given point and detects for intersection against all given polygons, returning the points of intersection in the results array.

Author: photonstorm

src/geom/intersects/GetRaysFromPointToPolygon.js

@@ -0,0 +1,83 @@
+/**
+ * @author       Richard Davey
+ * @copyright    2020 Photon Storm Ltd.
+ * @license      {@link https://opensource.org/licenses/MIT|MIT License}
+ */
+
+var Vector4 = require('../../math/Vector4');
+var GetLineToPolygon = require('./GetLineToPolygon');
+var Line = require('../line/Line');
+
+//  Temp calculation segment
+var segment = new Line();
+
+function CheckIntersects (angle, x, y, polygons, intersects)
+{
+    var dx = Math.cos(angle);
+    var dy = Math.sin(angle);
+
+    segment.setTo(x, y, x + dx, y + dy);
+
+    var closestIntersect = GetLineToPolygon(segment, polygons);
+
+    if (closestIntersect)
+    {
+        intersects.push(new Vector4(closestIntersect.x, closestIntersect.y, angle, closestIntersect.w));
+    }
+}
+
+function SortIntersects (a, b)
+{
+    return a.z - b.z;
+}
+
+/**
+ * Projects rays out from the given point to each line segment of the polygons.
+ *
+ * If the rays intersect with the polygons, the points of intersection are returned in an array.
+ *
+ * If no intersections are found, the returned array will be empty.
+ *
+ * Each Vector4 intersection result has the following properties:
+ *
+ * The `x` and `y` components contain the point of the intersection.
+ * The `z` component contains the angle of intersection.
+ * The `w` component contains the index of the polygon, in the given array, that triggered the intersection.
+ *
+ * @function Phaser.Geom.Intersects.GetRaysFromPointToPolygon
+ * @since 3.50.0
+ *
+ * @param {number} x - The x coordinate to project the rays from.
+ * @param {number} y - The y coordinate to project the rays from.
+ * @param {Phaser.Geom.Polygon | Phaser.Geom.Polygon[]} polygons - A single polygon, or array of polygons, to check against the rays.
+ *
+ * @return {Phaser.Math.Vector4[]} An array containing all intersections in Vector4s.
+ */
+var GetRaysFromPointToPolygon = function (x, y, polygons)
+{
+    if (!Array.isArray(polygons))
+    {
+        polygons = [ polygons ];
+    }
+
+    var intersects = [];
+
+    for (var i = 0; i < polygons.length; i++)
+    {
+        var points = polygons[i].points;
+
+        for (var p = 0; p < points.length; p++)
+        {
+            var angle = Math.atan2(points[p].y - y, points[p].x - x);
+
+            //  +- 0.00001 rads to catch lines behind segment corners
+            CheckIntersects(angle, x, y, polygons, intersects);
+            CheckIntersects(angle - 0.00001, x, y, polygons, intersects);
+            CheckIntersects(angle + 0.00001, x, y, polygons, intersects);
+        }
+    }
+
+    return intersects.sort(SortIntersects);
+};
+
+module.exports = GetRaysFromPointToPolygon;

src/geom/intersects/index.js

@@ -18,6 +18,7 @@ module.exports = {
     GetLineToLine: require('./GetLineToLine'),
     GetLineToPolygon: require('./GetLineToPolygon'),
     GetLineToRectangle: require('./GetLineToRectangle'),
+    GetRaysFromPointToPolygon: require('./GetRaysFromPointToPolygon'),
     GetRectangleIntersection: require('./GetRectangleIntersection'),
     GetRectangleToRectangle: require('./GetRectangleToRectangle'),
     GetRectangleToTriangle: require('./GetRectangleToTriangle'),