/// <summary>
/// This abstract class is extended by any type of primitive geometry that can be tested for
/// collisions with moving points or boxes. In this sample it is only extended by the
/// CollisionTriangle class. 
/// </summary>
public abstract class CollideableElement : Node
{
	/*
	 * CLASS PROPERTIES
	 */
	/// <summary>
	/// flag to indicate if the collideable
	/// element needs it's definition updated
	/// </summary>
	public bool NeedsUpdate;
	/// <summary>
	/// bounding box of collideable element 
	/// </summary>
	public Bounds box;
	/// <summary>
	/// all tree nodes in which this
	/// dynamic collidable element is in
	/// </summary>
	private List<CollisionTreeNode> treeNodes;
	/// <summary>
	/// recurse id used to compute selections
	/// without getting redundant elements
	/// </summary>
	private uint mLastSearchId;

	/*
	 * CONSTRUCTOR
	 */
	/// <summary>
	/// constructor for a collideable element
	/// </summary>
	public CollideableElement(TwelveCylinderGame newGame)
		: base(newGame)
	{
		treeNodes = new List<CollisionTreeNode>();
		mLastSearchId = 0;
	}

	/*
	 * ABSTRACT METHODS
	 */
	/// <summary>
	/// updates the bounding collision box definition
	/// to ensure it exactley contains the element
	/// </summary>
	public abstract void updateCollisionBox();

	/// <summary>
	/// intersect a moving point with the element
	/// </summary>
	public abstract void PointIntersect(ref MovingPointData pointData);

	/// <summary>
	/// intersects a moving box with the element
	/// </summary>
	public abstract bool BoxIntersect(MovingBoxData boxData, out float collisionDistance,
						out Vector3 collisionPosition, out Vector3 collisionNormal);

	/*
	 * TREE NODE LIST
	 */
	/// <summary>
	/// adds a tree node to this collidable element's containing list
	/// </summary>
	public virtual void AddTreeNode(CollisionTreeNode treeNode)
	{
		treeNodes.Add(treeNode);
	}

	/// <summary>
	/// removes a single tree node from this collidable element's containing list
	/// </summary>
	public virtual void RemoveTreeNode(CollisionTreeNode xTreeNode)
	{
		treeNodes.Remove(xTreeNode);
	}

	/// <summary>
	/// Removes this element from the tree
	/// </summary>
	public void RemoveFromAllNodes()
	{
		// remove element from all nodes it is associated with
		foreach (CollisionTreeNode n in treeNodes)
			n.RemoveElement(this);
		treeNodes.Clear();
	}
}