Geom.Intersects.GetLineToLine is a new function that will return a Vector3 containing the point of intersection between 2 line segments, with the z property holding the distance value.

src/geom/intersects/GetLineToLine.js

@@ -0,0 +1,63 @@
+/**
+ * @author       Richard Davey
+ * @copyright    2020 Photon Storm Ltd.
+ * @license      {@link https://opensource.org/licenses/MIT|MIT License}
+ */
+
+var Vector3 = require('../../math/Vector3');
+
+/**
+ * Checks for intersection between the two line segments and returns the intersection point as a Vector3,
+ * or `null` if the lines are parallel, or do not intersect.
+ *
+ * The `z` property of the Vector3 contains the intersection distance, which can be used to find
+ * the closest intersecting point from a group of line segments.
+ *
+ * @function Phaser.Geom.Intersects.GetLineToLine
+ * @since 3.25.0
+ *
+ * @param {Phaser.Geom.Line} line1 - The first line segment to check.
+ * @param {Phaser.Geom.Line} line2 - The second line segment to check.
+ * @param {Phaser.Math.Vector3} [out] - A Vector3 to store the intersection results in.
+ *
+ * @return {Phaser.Math.Vector3} A Vector3 containing the intersection results, or `null`.
+ */
+var GetLineToLine = function (line1, line2, out)
+{
+    var dx1 = line1.x2 - line1.x1;
+    var dy1 = line1.y2 - line1.y1;
+
+    var dx2 = line2.x2 - line2.x1;
+    var dy2 = line2.y2 - line2.y1;
+
+    var mag1 = Math.sqrt(dx1 * dx1 + dy1 * dy1);
+    var mag2 = Math.sqrt(dx2 * dx2 + dy2 * dy2);
+
+    //  Parallel?
+    if (dx1 / mag1 === dx2 / mag2 && dy1 / mag1 === dy2 / mag2)
+    {
+        return null;
+    }
+
+    var T2 = (dx1 * (line2.y1 - line1.y1) + dy1 * (line1.x1 - line2.x1)) / (dx2 * dy1 - dy2 * dx1);
+    var T1 = (line2.x1 + dx2 * T2 - line1.x1) / dx1;
+
+    //  Intersects?
+    if (T1 < 0 || T2 < 0 || T2 > 1)
+    {
+        return null;
+    }
+
+    if (out === undefined)
+    {
+        out = new Vector3();
+    }
+
+    return out.set(
+        line1.x1 + dx1 * T1,
+        line1.y1 + dy1 * T1,
+        T1
+    );
+};
+
+module.exports = GetLineToLine;

src/geom/intersects/index.js

@@ -15,6 +15,7 @@ module.exports = {
     GetCircleToCircle: require('./GetCircleToCircle'),
     GetCircleToRectangle: require('./GetCircleToRectangle'),
     GetLineToCircle: require('./GetLineToCircle'),
+    GetLineToLine: require('./GetLineToLine'),
     GetLineToRectangle: require('./GetLineToRectangle'),
     GetRectangleIntersection: require('./GetRectangleIntersection'),
     GetRectangleToRectangle: require('./GetRectangleToRectangle'),