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

  Program:   Visualization Toolkit
  Module:    vtkFrustumCoverageCuller.h
  Language:  C++
  Date:      $Date$
  Version:   $Revision$

  Copyright (c) 1993-2002 Ken Martin, Will Schroeder, Bill Lorensen 
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even 
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/
// .NAME vtkFrustumCoverageCuller - cull props based on frustum coverage
// .SECTION Description
// vtkFrustumCoverageCuller will cull props based on the coverage in
// the view frustum. The coverage is computed by enclosing the prop in
// a bounding sphere, projecting that to the viewing coordinate system, then
// taking a slice through the view frustum at the center of the sphere. This
// results in a circle on the plane slice through the view frustum. This
// circle is enclosed in a squared, and the fraction of the plane slice that
// this square covers is the coverage. This is a number between 0 and 1.
// If the number is less than the MinumumCoverage, the allocated render time
// for that prop is set to zero. If it is greater than the MaximumCoverage,
// the allocated render time is set to 1.0. In between, a linear ramp is used
// to convert coverage into allocated render time.


// .SECTION see also
// vtkCuller

#ifndef __vtkFrustumCoverageCuller_h
#define __vtkFrustumCoverageCuller_h

#include "vtkCuller.h"

#define VTK_CULLER_SORT_NONE          0
#define VTK_CULLER_SORT_FRONT_TO_BACK 1
#define VTK_CULLER_SORT_BACK_TO_FRONT 2

class vtkProp;
class vtkRenderer;

class VTK_RENDERING_EXPORT vtkFrustumCoverageCuller : public vtkCuller
{
public:
  static vtkFrustumCoverageCuller *New();
  vtkTypeRevisionMacro(vtkFrustumCoverageCuller,vtkCuller);
  void PrintSelf(ostream& os,vtkIndent indent);

  // Description:
  // Set/Get the minimum coverage - props with less coverage than this
  // are given no time to render (they are culled)
  vtkSetMacro( MinimumCoverage, float );
  vtkGetMacro( MinimumCoverage, float );

  // Description:
  // Set/Get the maximum coverage - props with more coverage than this are
  // given an allocated render time of 1.0 (the maximum)
  vtkSetMacro( MaximumCoverage, float );
  vtkGetMacro( MaximumCoverage, float );

  // Description:
  // Set the sorting style - none, front-to-back or back-to-front
  // The default is none
  vtkSetClampMacro( SortingStyle, int,
        VTK_CULLER_SORT_NONE, VTK_CULLER_SORT_BACK_TO_FRONT );
  vtkGetMacro(SortingStyle,int);
  void SetSortingStyleToNone()
        {this->SetSortingStyle(VTK_CULLER_SORT_NONE);};
  void SetSortingStyleToBackToFront()
    {this->SetSortingStyle(VTK_CULLER_SORT_BACK_TO_FRONT);};
  void SetSortingStyleToFrontToBack()
    {this->SetSortingStyle(VTK_CULLER_SORT_FRONT_TO_BACK);};
  const char *GetSortingStyleAsString(void);

//BTX
  // Description:
  // WARNING: INTERNAL METHOD - NOT INTENDED FOR GENERAL USE
  // DO NOT USE THESE METHODS OUTSIDE OF THE RENDERING PROCESS
  // Perform the cull operation
  // This method should only be called by vtkRenderer as part of
  // the render process
  float Cull( vtkRenderer *ren, vtkProp **propList,
              int& listLength, int& initialized );
//ETX

protected:
  vtkFrustumCoverageCuller();
  ~vtkFrustumCoverageCuller() {};

  float        MinimumCoverage;
  float        MaximumCoverage;
  int          SortingStyle;
private:
  vtkFrustumCoverageCuller(const vtkFrustumCoverageCuller&);  // Not implemented.
  void operator=(const vtkFrustumCoverageCuller&);  // Not implemented.
};

                                         
#endif
