// -*- c++ -*-

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

  Program:   Visualization Toolkit
  Module:    vtkUnstructuredGridVolumeRayCastIterator.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   vtkUnstructuredGridVolumeRayCastIterator
 *
 *
 *
 * vtkUnstructuredGridVolumeRayCastIterator is a superclass for iterating
 * over the intersections of a viewing ray with a group of unstructured
 * cells.  These iterators are created with a
 * vtkUnstructuredGridVolumeRayCastFunction.
 *
 * @sa
 * vtkUnstructuredGridVolumeRayCastFunction
 *
 */

#ifndef vtkUnstructuredGridVolumeRayCastIterator_h
#define vtkUnstructuredGridVolumeRayCastIterator_h

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

class vtkIdList;
class vtkDoubleArray;
class vtkDataArray;

class VTKRENDERINGVOLUME_EXPORT vtkUnstructuredGridVolumeRayCastIterator : public vtkObject
{
public:
  vtkTypeMacro(vtkUnstructuredGridVolumeRayCastIterator, vtkObject);
  void PrintSelf(ostream& os, vtkIndent indent) override;

  /**
   * Initializes the iteration to the start of the ray at the given screen
   * coordinates.
   */
  virtual void Initialize(int x, int y) = 0;

  /**
   * Get the intersections of the next several cells.  The cell ids are
   * stored in \c intersectedCells and the length of each ray segment
   * within the cell is stored in \c intersectionLengths.  The point
   * scalars \c scalars are interpolated and stored in \c nearIntersections
   * and \c farIntersections.  \c intersectedCells, \c intersectionLengths,
   * or \c scalars may be \c NULL to suppress passing the associated
   * information.  The number of intersections actually encountered is
   * returned.  0 is returned if and only if no more intersections are to
   * be found.
   */
  virtual vtkIdType GetNextIntersections(vtkIdList* intersectedCells,
    vtkDoubleArray* intersectionLengths, vtkDataArray* scalars, vtkDataArray* nearIntersections,
    vtkDataArray* farIntersections) = 0;

  ///@{
  /**
   * Set/get the bounds of the cast ray (in viewing coordinates).  By
   * default the range is [0,1].
   */
  vtkSetVector2Macro(Bounds, double);
  vtkGetVector2Macro(Bounds, double);
  ///@}

  // Description:
  // Set/get the maximum number of intersections returned with a call to
  // GetNextIntersections.  Set to 32 by default.
  vtkSetMacro(MaxNumberOfIntersections, vtkIdType);
  vtkGetMacro(MaxNumberOfIntersections, vtkIdType);

protected:
  vtkUnstructuredGridVolumeRayCastIterator();
  ~vtkUnstructuredGridVolumeRayCastIterator() override;

  double Bounds[2];

  vtkIdType MaxNumberOfIntersections;

private:
  vtkUnstructuredGridVolumeRayCastIterator(
    const vtkUnstructuredGridVolumeRayCastIterator&) = delete;
  void operator=(const vtkUnstructuredGridVolumeRayCastIterator&) = delete;
};

#endif // vtkUnstructuredGridRayCastIterator_h
