+ /**
+ * Make tux invicible for a short amount of time
+ */
+ virtual void make_invincible() = 0;
+ /**
+ * Deactivate user input for Tux
+ */
+ virtual void deactivate() = 0;
+ /**
+ * Give control back to user
+ */
+ virtual void activate() = 0;
+ /**
+ * Make Tux walk
+ */
+ virtual void walk(float speed) = 0;
+ /**
+ * Set player visible or not visible
+ */
+ virtual void set_visible(bool visible) = 0;
+ /**
+ * returns true if the player is currently visible (that is he was not set
+ * inivisible by the set_visible method)
+ */
+ virtual bool get_visible() = 0;