dox/Rendering/Volume/vtkUnstructuredGridPreIntegration.h

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

  Program:   Visualization Toolkit
  Module:    vtkUnstructuredGridPreIntegration.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.

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

/*
 * Copyright 2004 Sandia Corporation.
 * Under the terms of Contract DE-AC04-94AL85000, there is a non-exclusive
 * license for use of this work by or on behalf of the
 * U.S. Government. Redistribution and use in source and binary forms, with
 * or without modification, are permitted provided that this Notice and any
 * statement of authorship are reproduced on all copies.
 */

#ifndef __vtkUnstructuredGridPreIntegration_h
#define __vtkUnstructuredGridPreIntegration_h

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

class vtkVolumeProperty;

class VTKRENDERINGVOLUME_EXPORT vtkUnstructuredGridPreIntegration : public vtkUnstructuredGridVolumeRayIntegrator
{
public:
  vtkTypeMacro(vtkUnstructuredGridPreIntegration,
                       vtkUnstructuredGridVolumeRayIntegrator);
  static vtkUnstructuredGridPreIntegration *New();
  virtual void PrintSelf(ostream &os, vtkIndent indent);

  virtual void Initialize(vtkVolume *volume, vtkDataArray *scalars);

  virtual void Integrate(vtkDoubleArray *intersectionLengths,
                         vtkDataArray *nearIntersections,
                         vtkDataArray *farIntersections,
                         float color[4]);


  vtkGetObjectMacro(Integrator, vtkUnstructuredGridVolumeRayIntegrator);
  virtual void SetIntegrator(vtkUnstructuredGridVolumeRayIntegrator *);


  vtkSetMacro(IntegrationTableScalarResolution, int);
  vtkGetMacro(IntegrationTableScalarResolution, int);
  vtkSetMacro(IntegrationTableLengthResolution, int);
  vtkGetMacro(IntegrationTableLengthResolution, int);


  virtual double GetIntegrationTableScalarShift(int component = 0);
  virtual double GetIntegrationTableScalarScale(int component = 0);
  virtual double GetIntegrationTableLengthScale();


  vtkGetMacro(IncrementalPreIntegration, int);
  vtkSetMacro(IncrementalPreIntegration, int);
  vtkBooleanMacro(IncrementalPreIntegration, int);

  virtual float *GetPreIntegrationTable(int component = 0);


  float *GetTableEntry(double scalar_front, double scalar_back, double lenth,
                       int component = 0);


  float *GetIndexedTableEntry(int scalar_front_index, int scalar_back_index,
                              int length_index, int component = 0);

protected:
  vtkUnstructuredGridPreIntegration();
  ~vtkUnstructuredGridPreIntegration();

  vtkUnstructuredGridVolumeRayIntegrator *Integrator;

  vtkVolume *Volume;
  vtkVolumeProperty *Property;
  double MaxLength;

  int      NumComponents;
  float  **IntegrationTable;
  double  *IntegrationTableScalarShift;
  double  *IntegrationTableScalarScale;
  double   IntegrationTableLengthScale;
  vtkTimeStamp IntegrationTableBuilt;

  int IntegrationTableScalarResolution;
  int IntegrationTableLengthResolution;

  int IncrementalPreIntegration;

  virtual void BuildPreIntegrationTables(vtkDataArray *scalars);

private:
  vtkUnstructuredGridPreIntegration(const vtkUnstructuredGridPreIntegration&);  // Not implemented.
  void operator=(const vtkUnstructuredGridPreIntegration&);  // Not implemented
};

inline float *vtkUnstructuredGridPreIntegration::GetIndexedTableEntry(
                                                         int scalar_front_index,
                                                         int scalar_back_index,
                                                         int length_index,
                                                         int component)
{
  // Snap entries to bounds.  I don't really want to spend cycles doing
  // this, but I've had the ray caster give me values that are noticeably
  // out of bounds.
  if (scalar_front_index < 0) scalar_front_index = 0;
  if (scalar_front_index >= this->IntegrationTableScalarResolution)
    scalar_front_index = this->IntegrationTableScalarResolution - 1;
  if (scalar_back_index < 0) scalar_back_index = 0;
  if (scalar_back_index >= this->IntegrationTableScalarResolution)
    scalar_back_index = this->IntegrationTableScalarResolution - 1;
  if (length_index < 0) length_index = 0;
  if (length_index >= this->IntegrationTableLengthResolution)
    length_index = this->IntegrationTableLengthResolution - 1;

  return (  this->IntegrationTable[component]
          + 4*(  (  (  length_index*this->IntegrationTableScalarResolution
                     + scalar_back_index)
                  * this->IntegrationTableScalarResolution)
               + scalar_front_index));
}

inline float *vtkUnstructuredGridPreIntegration::GetTableEntry(
  double scalar_front, double scalar_back, double length, int component)
{
  int sfi = static_cast<int>(  scalar_front
                    *this->IntegrationTableScalarScale[component]
                  + this->IntegrationTableScalarShift[component] + 0.5);
  int sbi =  static_cast<int>(  scalar_back*this->IntegrationTableScalarScale[component]
                  + this->IntegrationTableScalarShift[component] + 0.5);
  int li =  static_cast<int>(length*this->IntegrationTableLengthScale + 0.5);
  return this->GetIndexedTableEntry(sfi, sbi, li, component);
}

#endif //__vtkUnstructuredGridPreIntegration_h