added distance to Pos3

src/lib/Pos3.hx

@@ -104,4 +104,8 @@ abstract Pos3(Vec3<Float>) from Vec3<Float> to Vec3<Float>{
 			z: Math.fround(this.z)
 		});
 	}
+
+	public function distance(rhs:Pos3):Float {
+		return Math.sqrt(Math.pow(this.x - rhs.x, 2) + Math.pow(this.y - rhs.y, 2) + Math.pow(this.z - rhs.z, 2));
+	}
 }