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

  Program:   Visualization Toolkit
  Module:    vtkGenericSubdivisionErrorMetric.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.

=========================================================================*/
/**
 * @class   vtkGenericSubdivisionErrorMetric
 * @brief   Objects that compute
 * error during cell tessellation.
 *
 *
 * Objects of that class answer the following question during the cell
 * subdivision: "does the edge need to be subdivided?" through
 * RequiresEdgeSubdivision().
 * The answer depends on the criterium actually used in the subclass of this
 * abstract class: a geometric-based error
 * metric (variation of edge from a straight line), an attribute-based error
 * metric (variation of the active attribute/component value from a linear
 * ramp) , a view-depend error metric, ...
 * Cell subdivision is performed in the context of the adaptor
 * framework: higher-order, or complex cells, are automatically tessellated
 * into simplices so that they can be processed with conventional
 * visualization algorithms.
 *
 * @sa
 * vtkGenericCellTessellator
*/

#ifndef vtkGenericSubdivisionErrorMetric_h
#define vtkGenericSubdivisionErrorMetric_h

#include "vtkCommonDataModelModule.h" // For export macro
#include "vtkObject.h"

class vtkGenericAttributeCollection;
class vtkGenericAdaptorCell;
class vtkGenericDataSet;

class VTKCOMMONDATAMODEL_EXPORT vtkGenericSubdivisionErrorMetric : public vtkObject
{
public:
  //@{
  /**
   * Standard VTK type and error macros.
   */
  vtkTypeMacro(vtkGenericSubdivisionErrorMetric,vtkObject);
  void PrintSelf(ostream& os, vtkIndent indent) VTK_OVERRIDE;
  //@}

  /**
   * Does the edge need to be subdivided according to the implemented
   * computation?
   * The edge is defined by its `leftPoint' and its `rightPoint'.
   * `leftPoint', `midPoint' and `rightPoint' have to be initialized before
   * calling RequiresEdgeSubdivision().
   * Their format is global coordinates, parametric coordinates and
   * point centered attributes: xyx rst abc de...
   * `alpha' is the normalized abscissa of the midpoint along the edge.
   * (close to 0 means close to the left point, close to 1 means close to the
   * right point)
   * \pre leftPoint_exists: leftPoint!=0
   * \pre midPoint_exists: midPoint!=0
   * \pre rightPoint_exists: rightPoint!=0
   * \pre clamped_alpha: alpha>0 && alpha<1
   * \pre valid_size: sizeof(leftPoint)=sizeof(midPoint)=sizeof(rightPoint)
   * =GetAttributeCollection()->GetNumberOfPointCenteredComponents()+6
   */
  virtual int RequiresEdgeSubdivision(double *leftPoint, double *midPoint,
                                      double *rightPoint, double alpha)=0;

  /**
   * Return the error at the mid-point. The type of error depends on the state
   * of the concrete error metric. For instance, it can return an absolute
   * or relative error metric.
   * See RequiresEdgeSubdivision() for a description of the arguments.
   * \pre leftPoint_exists: leftPoint!=0
   * \pre midPoint_exists: midPoint!=0
   * \pre rightPoint_exists: rightPoint!=0
   * \pre clamped_alpha: alpha>0 && alpha<1
   * \pre valid_size: sizeof(leftPoint)=sizeof(midPoint)=sizeof(rightPoint)
   * =GetAttributeCollection()->GetNumberOfPointCenteredComponents()+6
   * \post positive_result: result>=0
   */
  virtual double GetError(double *leftPoint, double *midPoint,
                          double *rightPoint, double alpha)=0;

  //@{
  /**
   * The cell that the edge belongs to.
   */
  void SetGenericCell(vtkGenericAdaptorCell *cell);
  vtkGetObjectMacro(GenericCell,vtkGenericAdaptorCell);
  //@}

  //@{
  /**
   * Set/Get the dataset to be tessellated.
   */
  void SetDataSet(vtkGenericDataSet *ds);
  vtkGetObjectMacro(DataSet,vtkGenericDataSet);
  //@}

protected:
  vtkGenericSubdivisionErrorMetric();
  ~vtkGenericSubdivisionErrorMetric() VTK_OVERRIDE;

  vtkGenericAdaptorCell *GenericCell;
  vtkGenericDataSet *DataSet;

private:
  vtkGenericSubdivisionErrorMetric(const vtkGenericSubdivisionErrorMetric&) VTK_DELETE_FUNCTION;
  void operator=(const vtkGenericSubdivisionErrorMetric&) VTK_DELETE_FUNCTION;
};

#endif
