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

  Program:   Visualization Toolkit
  Module:    vtkCoincidentTopologyResolutionPainter.h

  Copyright (c) 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 vtkCoincidentTopologyResolutionPainter - painter that resolves 
// conicident topology.
// .SECTION Description
// Provides the ability to shift the z-buffer to resolve coincident topology. 
// For example, if you'd like to draw a mesh with some edges a different color, 
// and the edges lie on the mesh, this feature can be useful to get nice 
// looking lines.

#ifndef __vtkCoincidentTopologyResolutionPainter_h
#define __vtkCoincidentTopologyResolutionPainter_h

#include "vtkPolyDataPainter.h"

class vtkInformationIntegerKey;
class vtkInformationDoubleKey;
class vtkInformationDoubleVectorKey;

class VTK_RENDERING_EXPORT vtkCoincidentTopologyResolutionPainter : 
  public vtkPolyDataPainter
{
public:
  static vtkCoincidentTopologyResolutionPainter* New();
  vtkTypeRevisionMacro(vtkCoincidentTopologyResolutionPainter, 
    vtkPolyDataPainter);
  void PrintSelf(ostream& os, vtkIndent indent);
  
  // Description:
  // Set/Get a global flag that controls whether coincident topology (e.g., a 
  // line on top of a polygon) is shifted to avoid z-buffer resolution (and 
  // hence rendering problems). If not off, there are two methods to choose 
  // from. PolygonOffset uses graphics systems calls to shift polygons, but 
  // does not distinguish vertices and lines from one another. ShiftZBuffer 
  // remaps the z-buffer to distinguish vertices, lines, and polygons, but 
  // does not always produce acceptable results. If you use the ShiftZBuffer 
  // approach, you may also want to set the ResolveCoincidentTopologyZShift 
  // value. (Note: not all mappers/graphics systems implement this 
  // functionality.)
  static vtkInformationIntegerKey* RESOLVE_COINCIDENT_TOPOLOGY();

  // Description:
  // Used to set the z-shift if ResolveCoincidentTopology is set to 
  // ShiftZBuffer.
  static vtkInformationDoubleKey* Z_SHIFT();

  // Description:
  // Used to set the polygon offset scale factor and units. Used when 
  // ResolveCoincidentTopology is set to PolygonOffset. 
  static vtkInformationDoubleVectorKey* POLYGON_OFFSET_PARAMETERS();
  
protected:
  vtkCoincidentTopologyResolutionPainter();
  ~vtkCoincidentTopologyResolutionPainter();

  // Description:
  // Called before RenderInternal() if the Information has been changed
  // since the last time this method was called.
  virtual void ProcessInformation(vtkInformation*);
 
  // These are method to set ivars. These are purpisefully protected.
  // The only means to affect these values is thru information object.
  vtkSetMacro(ResolveCoincidentTopology, int);
  vtkSetMacro(ZShift, double);
  void SetPolygonOffsetParameters(double factor, double units)
    {
    if (this->PolygonOffsetFactor != factor || 
      this->PolygonOffsetUnits != units)
      {
      this->PolygonOffsetFactor = factor;
      this->PolygonOffsetUnits = units;
      this->Modified();
      }
    }

  int ResolveCoincidentTopology;
  double PolygonOffsetFactor;
  double PolygonOffsetUnits;
  double ZShift;
private:
  vtkCoincidentTopologyResolutionPainter(const vtkCoincidentTopologyResolutionPainter&); // Not implemented.
  void operator=(const vtkCoincidentTopologyResolutionPainter&); // Not implemented.
};


#endif

