@return the walls

---------------------- ChangeMenuState --------------------------------- Changes the state of a menu item given the item identifier, the desired stat

----------------------------------------------------------------------------- The following 3 functions are taken from Petzold's book and enable the

------------------------- GetEntityFromID ----------------------------------- ------------------------------------------------------------------------

----------------------------- TwoCirclesOverlapped --------------------- Returns true if the two circles overlap ------------------------------------

accessors to the matrix elements

Add a unidirectional edge to the graph. @param fromID the ID number of the from node @param toID the ID number of the to node @param cost cost from >

This method is called to add a validated edge to the graph. @param edge the validated edge to add.

This method is called to add a validated edge to the graph. @param edge the validated edge to add.

Calculate the angle between this and another vector. @param v the other vector @return the angle between in radians

After calculating the entity's position it is then constrained by the domain constraint WRAP or REBOUND

Calculate the area of the polygon. @param contour an array of vertices that make up an open 2D polygon @return the area of the polygon

** returns the index for `key' if `key' is an appropriate key to live in ** the array part of the table, -1 otherwise. */