/*=========================================================================

  Program:   Visualization Toolkit
  Module:    $RCSfile: vtkHull.h,v $
  Language:  C++
  Date:      $Date: 2001/10/11 13:37:06 $
  Version:   $Revision: 1.17 $


Copyright (c) 1993-2001 Ken Martin, Will Schroeder, Bill Lorensen 
All rights reserved.

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 * Redistributions of source code must retain the above copyright notice,
   this list of conditions and the following disclaimer.

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   and/or other materials provided with the distribution.

 * Neither name of Ken Martin, Will Schroeder, or Bill Lorensen nor the names
   of any contributors may be used to endorse or promote products derived
   from this software without specific prior written permission.

 * Modified source versions must be plainly marked as such, and must not be
   misrepresented as being the original software.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS''
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

=========================================================================*/
// .NAME vtkHull - produce an n-sided convex hull
// .SECTION Description
// vtkHull is a filter which will produce an n-sided convex hull given a
// set of n planes. (The convex hull bounds the input polygonal data.)
// The hull is generated by squeezing the planes towards the input
// vtkPolyData, until the planes just touch the vtkPolyData. Then,
// the resulting planes are used to generate a polyhedron (i.e., hull)
// that is represented by triangles.
//
// The n planes can be defined in a number of ways including 1) manually 
// specifying each plane; 2) choosing the six face planes of the input's
// bounding box; 3) choosing the eight vertex planes of the input's
// bounding box; 4) choosing the twelve edge planes of the input's
// bounding box; and/or 5) using a recursively subdivided octahedron.
// Note that when specifying planes, the plane normals should point
// outside of the convex region.
//
// The output of this filter can be used in combination with vtkLODActor 
// to represent a levels-of-detail in the LOD hierarchy. Another use of
// this class is to manually specify the planes, and then generate the
// polyhedron from the planes (without squeezing the planes towards the
// input). The method GenerateHull() is used to do this.

#ifndef __vtkHull_h
#define __vtkHull_h

#include "vtkPolyDataToPolyDataFilter.h"

class vtkPlanes;

class VTK_GRAPHICS_EXPORT vtkHull : public vtkPolyDataToPolyDataFilter
{
public:
  static vtkHull *New();
  vtkTypeMacro(vtkHull,vtkPolyDataToPolyDataFilter);
  void PrintSelf(ostream& os, vtkIndent indent);

  // Description:
  // Remove all planes from the current set of planes.  
  void RemoveAllPlanes( void );

  // Description:
  // Add a plane to the current set of planes. It will be added at the
  // end of the list, and an index that can later be used to set this
  // plane's normal will be returned. The values A, B, C are from the
  // plane equation Ax + By + Cz + D = 0. This vector does not have to
  // have unit length (but it must have a non-zero length!). If a value
  // 0 > i >= -NumberOfPlanes is returned, then the plane is parallel
  // with a previously inserted plane, and |-i-1| is the index of the
  // plane that was previously inserted. If a value i < -NumberOfPlanes
  // is returned, then the plane normal is zero length.
  int  AddPlane( float A, float B, float C );
  int  AddPlane( float plane[3] );

  // Description:
  // Set the normal values for plane i. This is a plane that was already
  // added to the current set of planes with AddPlane(), and is now being
  // modified. The values A, B, C are from the plane equation 
  // Ax + By + Cz + D = 0. This vector does not have to have unit length.
  // Note that D is set to zero, except in the case of the method taking
  // a vtkPlanes* argument, where it is set to the D value defined there.
  void SetPlane( int i, float A, float B, float C );
  void SetPlane( int i, float plane[3] );

  // Description:
  // Variations of AddPlane()/SetPlane() that allow D to be set. These 
  // methods are used when GenerateHull() is used.
  int AddPlane( float A, float B, float C, float D );
  int AddPlane( float plane[3], float D );
  void SetPlane( int i, float A, float B, float C, float D );
  void SetPlane( int i, float plane[3], float D );

  // Description:
  // Set all the planes at once using a vtkPlanes implicit function.
  // This also sets the D value, so it can be used with GenerateHull().
  void SetPlanes( vtkPlanes *planes );

  // Description:
  // Get the number of planes in the current set of planes.
  vtkGetMacro( NumberOfPlanes, int );
  
  // Description:
  // Add the 8 planes that represent the vertices of a cube - the combination
  // of the three face planes connecting to a vertex - (1,1,1), (1,1,-1),
  // (1,-1,1), (1,-1,1), (-1,1,1), (-1,1,-1), (-1,-1,1), (-1,-1-1).
  void AddCubeVertexPlanes();

  // Description:
  // Add the 12 planes that represent the edges of a cube - halfway between
  // the two connecting face planes - (1,1,0), (-1,-1,0), (-1,1,0), (1,-1,0),
  // (0,1,1), (0,-1,-1), (0,1,-1), (0,-1,1), (1,0,1), (-1,0,-1),
  // (1,0,-1), (-1,0,1)
  void AddCubeEdgePlanes();

  // Description:
  // Add the six planes that make up the faces of a cube - (1,0,0),
  // (-1, 0, 0), (0,1,0), (0,-1,0), (0,0,1), (0,0,-1)
  void AddCubeFacePlanes();

  // Description:
  // Add the planes that represent the normals of the vertices of a
  // polygonal sphere formed by recursively subdividing the triangles
  // in an octahedron.  Each triangle is subdivided by connecting the
  // midpoints of the edges thus forming 4 smaller triangles. The
  // level indicates how many subdivisions to do with a level of 0
  // used to add the 6 planes from the original octahedron, level 1
  // will add 18 planes, and so on.
  void AddRecursiveSpherePlanes( int level );

  // Description:
  // A special method that is used to generate a polyhedron directly
  // from a set of n planes. The planes that are supplied by the user
  // are not squeezed towards the input data (in fact the user need
  // not specify an input). To use this method, you must provide an
  // instance of vtkPolyData into which the points and cells defining
  // the polyhedron are placed. You must also provide a bounding box
  // where you expect the resulting polyhedron to lie. This can be
  // a very generous fit, it's only used to create the initial polygons
  // that are eventually clipped.
  void GenerateHull(vtkPolyData *pd, float *bounds);
  void GenerateHull(vtkPolyData *pd, float xmin, float xmax,
                    float ymin, float ymax, float zmin, float zmax);

protected:
  vtkHull();
  ~vtkHull();

  // The planes - 4 doubles per plane for A, B, C, D
  double     *Planes;

  // This indicates the current size (in planes - 4*sizeof(float)) of 
  // the this->Planes array. Planes are allocated in chunks so that the
  // array does not need to be reallocated every time a new plane is added
  int       PlanesStorageSize;

  // The number of planes that have been added
  int       NumberOfPlanes;

  // Internal method used to find the position of each plane
  void      ComputePlaneDistances();

  // Internal method used to create the actual polygons from the set 
  // of planes
  void      ClipPolygonsFromPlanes( vtkPoints *points, vtkCellArray *polys,
                                    float *bounds );

  // Internal method used to create the initial "big" polygon from the
  // plane equation. This polygon is clipped by all other planes to form
  // the final polygon (or it may be clipped entirely)
  void      CreateInitialPolygon( double *, int, float * );

  // The method that does it all...
  void      Execute();
private:
  vtkHull(const vtkHull&);  // Not implemented.
  void operator=(const vtkHull&);  // Not implemented.
};

#endif
