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

  Program:   Visualization Toolkit
  Module:    vtkDepthSortPolyData.h
  Language:  C++
  Date:      $Date$
  Version:   $Revision$
  Thanks:    Scott Hill for implementing this class


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

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

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

 * Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   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
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

=========================================================================*/
// .NAME vtkDepthSortPolyData - sort poly data along camera view direction
// .SECTION Description
// vtkDepthSortPolyData rearranges the order of cells so that certain
// rendering operations (e.g., transparency or Painter's algorithms)
// generate correct results. To use this filter you must specify the
// direction vector along which to sort the cells. You can do this by 
// specifying a camera and/or prop to define a view direction; or 
// explicitly set a view direction.

// .SECTION Caveats
// The sort operation will not work well for long, thin primitives, or cells
// that intersect, overlap, or interpenetrate each other.

#ifndef __vtkDepthSortPolyData_h
#define __vtkDepthSortPolyData_h

#include "vtkPolyDataToPolyDataFilter.h"
#include "vtkCamera.h"
#include "vtkProp3D.h"
#include "vtkTransform.h"

#define VTK_DIRECTION_BACK_TO_FRONT 0
#define VTK_DIRECTION_FRONT_TO_BACK 1
#define VTK_DIRECTION_SPECIFIED_VECTOR 2

class VTK_EXPORT vtkDepthSortPolyData : public vtkPolyDataToPolyDataFilter 
{
public:
  // Description:
  // Instantiate object.
  static vtkDepthSortPolyData *New();

  vtkTypeMacro(vtkDepthSortPolyData,vtkPolyDataToPolyDataFilter);
  void PrintSelf(ostream& os, vtkIndent indent);

  // Description:
  // Specify the sort method for the polygonal primitives.
  vtkSetMacro(Direction,int);
  vtkGetMacro(Direction,int);
  void SetDirectionToFrontToBack() {
    this->SetDirection(VTK_DIRECTION_FRONT_TO_BACK);};
  void SetDirectionToBackToFront() {
    this->SetDirection(VTK_DIRECTION_BACK_TO_FRONT);};
  void SetDirectionToSpecifiedVector() {
    this->SetDirection(VTK_DIRECTION_SPECIFIED_VECTOR);};

  // Description:
  // Specify a camera that is used to define a view direction along which
  // the cells are sorted. This ivar only has effect if the direction is set
  // to front-to-back or back-to-front, and a camera is specified.
  vtkSetObjectMacro(Camera,vtkCamera);
  vtkGetObjectMacro(Camera,vtkCamera);

  // Description:
  // Specify a transformation matrix (via the vtkProp3D::GetMatrix() method)
  // that is used to include the effects of transformation. This ivar only
  // has effect if the direction is set to front-to-back or back-to-front,
  // and a camera is specified. Specifying the vtkProp3D is optional.
  void SetProp3D(vtkProp3D *);
  vtkProp3D *GetProp3D();

  // Description:
  // Set/Get the sort direction. This ivar only has effect if the sort
  // direction is set to SetDirectionToSpecifiedVector(). The sort occurs
  // in the direction of the vector.
  vtkSetVector3Macro(Vector,double);
  vtkGetVectorMacro(Vector,double,3);

  // Description:
  // Set/Get the sort origin. This ivar only has effect if the sort
  // direction is set to SetDirectionToSpecifiedVector(). The sort occurs
  // in the direction of the vector, with this point specifying the
  // origin.
  vtkSetVector3Macro(Origin,double);
  vtkGetVectorMacro(Origin,double,3);

  // Description:
  // Set/Get a flag that controls the generation of scalar values
  // corresponding to the sort order. If enabled, the output of this
  // filter will include scalar values that range from 0 to (ncells-1),
  // where 0 is closest to the sort direction.
  vtkSetMacro(SortScalars, int);
  vtkGetMacro(SortScalars, int);
  vtkBooleanMacro(SortScalars, int);

  // Description:
  // Return MTime also considering the dependent objects: the camera
  // and/or the prop3D.
  unsigned long GetMTime();

protected:
  vtkDepthSortPolyData();
  ~vtkDepthSortPolyData();
  vtkDepthSortPolyData(const vtkDepthSortPolyData&) {};
  void operator=(const vtkDepthSortPolyData&) {};

  void Execute();
  void ComputeProjectionVector(double vector[3], double origin[3]);

  int Direction;
  vtkCamera *Camera;
  vtkProp3D *Prop3D;
  vtkTransform *Transform;
  double Vector[3];
  double Origin[3];
  int SortScalars;
  
};

#endif
