WorldManager.h

///
/// The game world manager
///

#ifndef __WORLD_MANAGER_H__
#define __WORLD_MANAGER_H__

#include "Box.h"
#include "Circle.h"
#include "ObjectList.h"
#include "Line.h"
#include "Manager.h"
#include "Position.h"
#include "SceneGraph.h"
#include "ViewObject.h"

#define MAX_ALTITUDE 4                 ///< Drawing order 0 to MAX

class WorldManager : public Manager {

 private:
  WorldManager();                      ///< Private since a singleton.
  WorldManager (WorldManager const&);  ///< Don't allow copy.
  void operator=(WorldManager const&); ///< Don't allow assignment.
  int obj_id;                          ///< Next object id to assign.
  int next_level;                      ///< Next level to assign (0 no change).

 protected:
  SceneGraph scene_graph;       ///< Storage for all objects, Game and View.
  ObjectList deletions;         ///< List of all GameObjects to delete.
  GameObject *p_view_following; ///< GameObject view is following.
  Box boundary;                 ///< World boundaries.
  Box view;                     ///< Player window view.

 public:
  ~WorldManager();

  /// Get the one and only instance of the WorldManager.
  static WorldManager &getInstance();

  /// Startup the game world (initialize everthing to empty).
  /// Return 0.
  int startUp();

  /// Shutdown the game world.
  void shutDown();

  /// Add Object to world.
  /// Return 0 if ok, else -1.
  int insertObject(GameObject *p_go);
  int insertObject(ViewObject *p_vo);

  /// Remove Object from world.
  /// Return 0 if ok, else -1.
  int removeObject(GameObject *p_go);
  int removeObject(ViewObject *p_vo);

  /// Return a list of all GameObjects in world.
  /// Return NULL if list is empty.
  ObjectList getAllGameObjects(void);

  /// Return a list of all ViewObjects in world.
  /// Return NULL if list is empty.
  ObjectList getAllViewObjects(void);

  /// Indicate object is to be deleted at end of current game loop.
  /// Return 0 if ok, else -1.
  int markForDelete(Object *p_o);

  /// Update world.
  /// Send "step" event to all interested objects.
  /// Update positions of GameObjects based on their velocities.
  /// Update the SceneGraph for those marked for updates.
  /// Lastly, delete GameObjectsmarked for deletion.
  void update();

  /// Draw, sending draw event to all GameObjects in view.
  /// Draw bottom up, from -MAX_ALTITUDE to MAX_ALTITUDE
  /// Draw ViewObjects last.
  void draw();

  /// Move GameObject. 
  /// If no collision with solid, move ok else don't move object.
  /// If p_go is Spectral, move ok.
  /// If move ok, adjust camera if following this GameObject.
  /// Return 0 if move ok, else -1 if collision with solid.
  int moveGameObject(GameObject *p_go, Position where);

  /// Return list of GameObjects collided with at Position 'where'.
  /// Collisions only with solid GameObjects.
  /// Does not consider if p_go is solid or not.
  ObjectList isCollision(GameObject *p_go, Position where);

  /// Return list of all GameObjects at Position 'where'.  
  /// Does include bounding boxes. Return empty list if none found.
  ObjectList gameObjectsAtPosition(Position where);

  /// Return list of all GameObjects in Box.
  /// Does include bounding boxes. Return empty list if none found.
  ObjectList gameObjectsInBox(Box box);

  /// Return a list of all GameObjects on line from point1 to point2.
  /// Does include bounding boxes. Return empty list if none found.
  ObjectList gameObjectsOnLine(Line line);

  /// Return a list of all GameObjects in circle.
  /// Does include bounding boxes. Return empty list if none found.
  ObjectList gameObjectsInCircle(Circle circle);

  /// Get game world boundary.
  Box getBoundary();

  /// Set game world boundary.
  void setBoundary(Box new_boundary);

  /// Get camera view for game world.
  Box getView();

  /// Set camera view for game world.
  void setView(Box new_view);

  /// Set camera view to center camera on GameObject.
  /// If p_new_view_following not legit, return -1 else return 0.
  /// Set to NULL to stop following.
  int setViewFollowing(GameObject *p_new_view_following);

  /// Set camera view to center on Position view_pos.
  /// View edge will not go beyond world boundary.
  void setViewPosition(Position view_pos);

  /// Return current game level.
  int getLevel();

  /// Set game level. Return 0 if ok, else -1.
  int setLevel(int new_level);

  /// Return a reference to SceneGraph.
  SceneGraph &getSceneGraph();
};

#endif // __WORLD_MANAGER_H__