Fixed unproject issues with new Ortho matrices

src/Math/babylon.math.ts

@@ -1227,7 +1227,7 @@
             world.multiplyToRef(view, matrix)
             matrix.multiplyToRef(projection, matrix);
             matrix.invert();
-            var screenSource = new Vector3(source.x / viewportWidth * 2 - 1, -(source.y / viewportHeight * 2 - 1), source.z);
+            var screenSource = new Vector3(source.x / viewportWidth * 2 - 1, -(source.y / viewportHeight * 2 - 1), 2 * source.z - 1.0);
             var vector = Vector3.TransformCoordinates(screenSource, matrix);
             var num = screenSource.x * matrix.m[3] + screenSource.y * matrix.m[7] + screenSource.z * matrix.m[11] + matrix.m[15];