//============================================================================
// viewfrus.hpp : GENERAL perspective viewing frustum class definition
//============================================================================

#ifndef VIEWFRUS
#define VIEWFRUS

#include "vect3d.hpp"
#include "plane.hpp"
#include "camera.hpp"

// NEAR PLANE TYPES (USED IN GENERALIZED UPDATE)
#define USESPTS 0
#define USEFARTHEST 1
#define USECLOSEST 2

class ViewFrustum
{
 public:

  //--------------------------------------------------------------------------
  // VIEW-FRUSTUM GEOMETRY (Pts ARE CCW W/ RESPECT TO THE VIEWER)
  //--------------------------------------------------------------------------
  Vect3d* sPts;     // GIVEN SILHOUETTE EDGES (3D POLYLINE). 
  Vect3d* NearPts;  // NEAR FACE VERTICES (define vertices of one end of frustum)
  Vect3d* FarPts;   // FAR FACE VERTICES (define other end of frustum)
  int NumSides;     // NUMBER OF SIDE PLANES, NearPts, AND FarPts
  Plane* Planes;    // ARRAY OF VF PLANES (FIRST ARE SIDES AND LAST TWO ELEMENTS ARE THE NEAR AND FAR PLANES)
  int NumPlanes;    // NumSides + Near + Far (optional)

  //--------------------------------------------------------------------------
  // Camera frustum constructor: Prepares the generalized ViewFrustum to be used for VIEW frustum
  // culling (four sides, near and far plane, etc defined by the Camera class).
  //--------------------------------------------------------------------------
  ViewFrustum(int numpts=4);

  //--------------------------------------------------------------------------
  // Shadow frustum constructor: Stores the given set of points to be used to define the frustum
  // when an update is called. The sPts should be a 3D polygon or a set of occluder edges.
  // NOTE: NOT REQUIRED IF COMPLETE UPDATE IS REQUIRED (using generalized Update)
  //--------------------------------------------------------------------------
  ViewFrustum(Vect3d* spts, int numpts);

  //--------------------------------------------------------------------------
  // Destructor
  //--------------------------------------------------------------------------
  ~ViewFrustum();

  //--------------------------------------------------------------------------
  // Initialization routine for the NearPts, FarPts, and Planes arrays.
  //--------------------------------------------------------------------------
  void Init(int numpts);

  //--------------------------------------------------------------------------
  // "GENERALIZED" Update routine : this update is called by the other update
  // routines.
  // Type "USENEARPTS": inits for a "Shadow" frustum where the near
  //   plane is defined by the plane created by the near pts (the near pts should
  //   be a 3D planar polygon). The COP is the center-of-projection in WORLD
  //   coordinates, ViewDir is the current viewing direction, and the FarDist is
  //   the distance to the far plane in the direction of ViewDir.
  // Type "USEFARTHEST": Uses the FARTHEST pt in the NearPts array along the
  //   ViewDir to define the near plane.
  // Type "USECLOSEST": Uses the CLOSEST pt in the NearPts array along the
  //   ViewDir to define the near plane.
  // IMPORTANT: NearPts are assumed to be ccw w/ respect to viewer. ViewDir must
  //   be NORMALIZED. COP and NearPts are in WORLD COORDS.
  //--------------------------------------------------------------------------
  void Update(Vect3d cop, Vect3d viewdir, float fardist, int Type);

  //--------------------------------------------------------------------------
  // OCCLUDER SET UPDATE ROUTINE: Requires EVERYTHING since it first destroys
  // the old Frustum and then builds a new one given the new parameters. This
  // will be useful if the ViewFrustum is NOT supposed to store the "occluder",
  // but rather a set of occluder edges. The same rules apply as in the second
  // update routine (I will actually call it after NearPts is created).
  //--------------------------------------------------------------------------
  void Update(Vect3d* spts, int numpts, Vect3d cop, Vect3d viewdir, float fardist, int Type);

  //--------------------------------------------------------------------------
  // CAMERA UPDATE ROUTINE : UPDATE THE FRUSTUM FOR A CAMERA SYSTEM (LAST TWO
  // ELEMENTS OF Sides IS NEAR AND FAR). Updates the ViewFrustum as a normal
  // VIEWING frustum.
  //--------------------------------------------------------------------------
  void ViewFrustum::Update(Camera* Cam);

  //--------------------------------------------------------------------------
  // CHECKS IF AN EDGE INTERSECTS THE VIEW-FRUSTUM
  //--------------------------------------------------------------------------
  int EdgeIntersect(Vect3d Start, Vect3d End) const;
};

#endif