+import eu.svjatoslav.sixth.e3d.math.TransformsStack;
+import eu.svjatoslav.sixth.e3d.math.Vertex;
+
+/**
+ * Tracks the position of the user in the 3D space.
+ * <p>
+ * It can be used to determine the angle between the user and the object.
+ * Also, it can be used to determine the distance between the user and the object.
+ */