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

  Program:   Visualization Toolkit
  Module:    vtkContourFilter.cxx

  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.

=========================================================================*/
#include "vtkContourFilter.h"

#include "vtkCell.h"
#include "vtkCellArray.h"
#include "vtkCellData.h"
#include "vtkContourGrid.h"
#include "vtkContourValues.h"
#include "vtkCutter.h"
#include "vtkGarbageCollector.h"
#include "vtkGenericCell.h"
#include "vtkGridSynchronizedTemplates3D.h"
#include "vtkImageData.h"
#include "vtkInformation.h"
#include "vtkInformationVector.h"
#include "vtkMergePoints.h"
#include "vtkObjectFactory.h"
#include "vtkPointData.h"
#include "vtkPolyData.h"
#include "vtkRectilinearGrid.h"
#include "vtkRectilinearSynchronizedTemplates.h"
#include "vtkSimpleScalarTree.h"
#include "vtkStreamingDemandDrivenPipeline.h"
#include "vtkStructuredGrid.h"
#include "vtkSynchronizedTemplates2D.h"
#include "vtkSynchronizedTemplates3D.h"
#include "vtkTimerLog.h"
#include "vtkUniformGrid.h"
#include "vtkUnstructuredGrid.h"
#include "vtkIncrementalPointLocator.h"
#include "vtkContourHelper.h"

#include <math.h>

vtkStandardNewMacro(vtkContourFilter);
vtkCxxSetObjectMacro(vtkContourFilter,ScalarTree,vtkScalarTree);

// Construct object with initial range (0,1) and single contour value
// of 0.0.
vtkContourFilter::vtkContourFilter()
{
  this->ContourValues = vtkContourValues::New();

  this->ComputeNormals = 1;
  this->ComputeGradients = 0;
  this->ComputeScalars = 1;

  this->Locator = NULL;

  this->UseScalarTree = 0;
  this->ScalarTree = NULL;

  this->OutputPointsPrecision = DEFAULT_PRECISION;

  this->GenerateTriangles = 1;

  this->SynchronizedTemplates2D = vtkSynchronizedTemplates2D::New();
  this->SynchronizedTemplates3D = vtkSynchronizedTemplates3D::New();
  this->GridSynchronizedTemplates = vtkGridSynchronizedTemplates3D::New();
  this->RectilinearSynchronizedTemplates = vtkRectilinearSynchronizedTemplates::New();

  // by default process active point scalars
  this->SetInputArrayToProcess(0,0,0,vtkDataObject::FIELD_ASSOCIATION_POINTS,
                               vtkDataSetAttributes::SCALARS);

  this->GetInformation()->Set(vtkAlgorithm::PRESERVES_RANGES(), 1);
  this->GetInformation()->Set(vtkAlgorithm::PRESERVES_BOUNDS(), 1);
}

vtkContourFilter::~vtkContourFilter()
{
  this->ContourValues->Delete();
  if ( this->Locator )
    {
    this->Locator->UnRegister(this);
    this->Locator = NULL;
    }
  if ( this->ScalarTree )
    {
    this->ScalarTree->Delete();
    this->ScalarTree = 0;
    }
  this->SynchronizedTemplates2D->Delete();
  this->SynchronizedTemplates3D->Delete();
  this->GridSynchronizedTemplates->Delete();
  this->RectilinearSynchronizedTemplates->Delete();
}

// Overload standard modified time function. If contour values are modified,
// then this object is modified as well.
unsigned long vtkContourFilter::GetMTime()
{
  unsigned long mTime=this->Superclass::GetMTime();
  unsigned long time;

  if (this->ContourValues)
    {
    time = this->ContourValues->GetMTime();
    mTime = ( time > mTime ? time : mTime );
    }
  if (this->Locator)
    {
    time = this->Locator->GetMTime();
    mTime = ( time > mTime ? time : mTime );
    }

  return mTime;
}

int vtkContourFilter::RequestUpdateExtent(vtkInformation* request,
                                          vtkInformationVector** inputVector,
                                          vtkInformationVector* outputVector)
{
  vtkInformation* inInfo = inputVector[0]->GetInformationObject(0);
  vtkDataSet *input =
    vtkDataSet::SafeDownCast(inInfo->Get(vtkDataObject::DATA_OBJECT()));

  int numContours=this->ContourValues->GetNumberOfContours();
  double *values=this->ContourValues->GetValues();

  vtkInformation *fInfo =
    vtkDataObject::GetActiveFieldInformation(inInfo,
                                             vtkDataObject::FIELD_ASSOCIATION_POINTS,
                                             vtkDataSetAttributes::SCALARS);
  int sType = VTK_DOUBLE;
  if (fInfo)
    {
    sType = fInfo->Get(vtkDataObject::FIELD_ARRAY_TYPE());
    }

  // handle 2D images
  int i;
  if (vtkImageData::SafeDownCast(input) && sType != VTK_BIT &&
      !vtkUniformGrid::SafeDownCast(input))
    {
    int dim = 3;
    int *uExt = inInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT());
    if (uExt[0] == uExt[1])
      {
      --dim;
      }
    if (uExt[2] == uExt[3])
      {
      --dim;
      }
    if (uExt[4] == uExt[5])
      {
      --dim;
      }

    if ( dim == 2 )
      {
      this->SynchronizedTemplates2D->SetNumberOfContours(numContours);
      for (i=0; i < numContours; i++)
        {
        this->SynchronizedTemplates2D->SetValue(i,values[i]);
        }
      this->SynchronizedTemplates2D->SetComputeScalars(this->ComputeScalars);
      return this->SynchronizedTemplates2D->
        ProcessRequest(request,inputVector,outputVector);
      }
    else if (dim == 3)
      {
      this->SynchronizedTemplates3D->SetNumberOfContours(numContours);
      for (i=0; i < numContours; i++)
        {
        this->SynchronizedTemplates3D->SetValue(i,values[i]);
        }
      this->SynchronizedTemplates3D->SetComputeNormals(this->ComputeNormals);
      this->SynchronizedTemplates3D->SetComputeGradients(this->ComputeGradients);
      this->SynchronizedTemplates3D->SetComputeScalars(this->ComputeScalars);
      this->SynchronizedTemplates3D->SetGenerateTriangles(this->GenerateTriangles);
      return this->SynchronizedTemplates3D->
        ProcessRequest(request,inputVector,outputVector);
      }
    } //if image data

  // handle 3D RGrids
  if (vtkRectilinearGrid::SafeDownCast(input) && sType != VTK_BIT)
    {
    int *uExt = inInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT());
    // if 3D
    if (uExt[0] < uExt[1] && uExt[2] < uExt[3] && uExt[4] < uExt[5])
      {
      this->RectilinearSynchronizedTemplates->SetNumberOfContours(numContours);
      for (i=0; i < numContours; i++)
        {
        this->RectilinearSynchronizedTemplates->SetValue(i,values[i]);
        }
      this->RectilinearSynchronizedTemplates->SetComputeNormals(this->ComputeNormals);
      this->RectilinearSynchronizedTemplates->SetComputeGradients(this->ComputeGradients);
      this->RectilinearSynchronizedTemplates->SetComputeScalars(this->ComputeScalars);
      this->RectilinearSynchronizedTemplates->SetGenerateTriangles(this->GenerateTriangles);
      return this->RectilinearSynchronizedTemplates->
        ProcessRequest(request,inputVector,outputVector);
      }
    } //if 3D RGrid

  // handle 3D SGrids
  if (vtkStructuredGrid::SafeDownCast(input) && sType != VTK_BIT)
    {
    int *uExt = inInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT());
    // if 3D
    if (uExt[0] < uExt[1] && uExt[2] < uExt[3] && uExt[4] < uExt[5])
      {
      this->GridSynchronizedTemplates->SetNumberOfContours(numContours);
      for (i=0; i < numContours; i++)
        {
        this->GridSynchronizedTemplates->SetValue(i,values[i]);
        }
      this->GridSynchronizedTemplates->SetComputeNormals(this->ComputeNormals);
      this->GridSynchronizedTemplates->SetComputeGradients(this->ComputeGradients);
      this->GridSynchronizedTemplates->SetComputeScalars(this->ComputeScalars);
      this->GridSynchronizedTemplates->SetGenerateTriangles(this->GenerateTriangles);
      return this->GridSynchronizedTemplates->
        ProcessRequest(request,inputVector,outputVector);
      }
    } //if 3D SGrid

  inInfo->Set(vtkStreamingDemandDrivenPipeline::EXACT_EXTENT(), 1);
  return 1;
}

// General contouring filter.  Handles arbitrary input.
//
int vtkContourFilter::RequestData(
  vtkInformation* request,
  vtkInformationVector** inputVector,
  vtkInformationVector* outputVector)
{
  // get the input
  vtkInformation* inInfo = inputVector[0]->GetInformationObject(0);
  vtkDataSet *input = vtkDataSet::SafeDownCast(
    inInfo->Get(vtkDataObject::DATA_OBJECT()));
  if (!input)
    {
    return 0;
    }

  // get the contours
  int numContours=this->ContourValues->GetNumberOfContours();
  double *values=this->ContourValues->GetValues();
  int i;

  // is there data to process?
  if (!this->GetInputArrayToProcess(0, inputVector))
    {
    return 1;
    }

  int sType = this->GetInputArrayToProcess(0, inputVector)->GetDataType();

  // handle 2D images
  if (vtkImageData::SafeDownCast(input) && sType != VTK_BIT &&
      !vtkUniformGrid::SafeDownCast(input))
    {
    int dim = 3;
    int *uExt = inInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT());
    if (uExt[0] == uExt[1])
      {
      --dim;
      }
    if (uExt[2] == uExt[3])
      {
      --dim;
      }
    if (uExt[4] == uExt[5])
      {
      --dim;
      }

    if ( dim == 2 )
      {
      this->SynchronizedTemplates2D->SetNumberOfContours(numContours);
      for (i=0; i < numContours; i++)
        {
        this->SynchronizedTemplates2D->SetValue(i,values[i]);
        }
      this->SynchronizedTemplates2D->
        SetInputArrayToProcess(0,this->GetInputArrayInformation(0));
      return
        this->SynchronizedTemplates2D->ProcessRequest(request,inputVector,outputVector);
      }
    else if ( dim == 3 )
      {
      this->SynchronizedTemplates3D->SetNumberOfContours(numContours);
      for (i=0; i < numContours; i++)
        {
        this->SynchronizedTemplates3D->SetValue(i,values[i]);
        }
      this->SynchronizedTemplates3D->SetComputeNormals(this->ComputeNormals);
      this->SynchronizedTemplates3D->SetComputeGradients(this->ComputeGradients);
      this->SynchronizedTemplates3D->SetComputeScalars(this->ComputeScalars);
      this->SynchronizedTemplates3D->SetGenerateTriangles(this->GenerateTriangles);
      this->SynchronizedTemplates3D->
        SetInputArrayToProcess(0,this->GetInputArrayInformation(0));

      return this->SynchronizedTemplates3D->ProcessRequest(request,inputVector,outputVector);
      }
    } //if image data

  // handle 3D RGrids
  if (vtkRectilinearGrid::SafeDownCast(input) && sType != VTK_BIT)
    {
    int *uExt = inInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT());
    // if 3D
    if (uExt[0] < uExt[1] && uExt[2] < uExt[3] && uExt[4] < uExt[5])
      {
      this->RectilinearSynchronizedTemplates->SetNumberOfContours(numContours);
      for (i=0; i < numContours; i++)
        {
        this->RectilinearSynchronizedTemplates->SetValue(i,values[i]);
        }
      this->RectilinearSynchronizedTemplates->SetComputeNormals(this->ComputeNormals);
      this->RectilinearSynchronizedTemplates->SetComputeGradients(this->ComputeGradients);
      this->RectilinearSynchronizedTemplates->SetComputeScalars(this->ComputeScalars);
      this->RectilinearSynchronizedTemplates->SetGenerateTriangles(this->GenerateTriangles);
      this->RectilinearSynchronizedTemplates->
        SetInputArrayToProcess(0,this->GetInputArrayInformation(0));
      return this->RectilinearSynchronizedTemplates->
        ProcessRequest(request,inputVector,outputVector);
      }
    } // if 3D Rgrid

  // handle 3D SGrids
  if (vtkStructuredGrid::SafeDownCast(input) && sType != VTK_BIT)
    {
    int *uExt = inInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT());
    // if 3D
    if (uExt[0] < uExt[1] && uExt[2] < uExt[3] && uExt[4] < uExt[5])
      {
      this->GridSynchronizedTemplates->SetNumberOfContours(numContours);
      for (i=0; i < numContours; i++)
        {
        this->GridSynchronizedTemplates->SetValue(i,values[i]);
        }
      this->GridSynchronizedTemplates->SetComputeNormals(this->ComputeNormals);
      this->GridSynchronizedTemplates->SetComputeGradients(this->ComputeGradients);
      this->GridSynchronizedTemplates->SetComputeScalars(this->ComputeScalars);
      this->GridSynchronizedTemplates->SetGenerateTriangles(this->GenerateTriangles);
      this->GridSynchronizedTemplates->
        SetInputArrayToProcess(0,this->GetInputArrayInformation(0));
      return this->GridSynchronizedTemplates->
        ProcessRequest(request,inputVector,outputVector);
      }
    } //if 3D SGrid

  vtkIdType cellId;
  int abortExecute=0;
  vtkIdList *cellPts;
  vtkDataArray *inScalars;
  vtkCellArray *newVerts, *newLines, *newPolys;
  vtkPoints *newPts;
  vtkIdType numCells, estimatedSize;
  vtkDataArray *cellScalars;

  vtkInformation* info = outputVector->GetInformationObject(0);
  vtkPolyData *output = vtkPolyData::SafeDownCast(
    info->Get(vtkDataObject::DATA_OBJECT()));
  if (!output) {return 0;}


  vtkPointData *inPd=input->GetPointData(), *outPd=output->GetPointData();
  vtkCellData *inCd=input->GetCellData(), *outCd=output->GetCellData();

  vtkDebugMacro(<< "Executing contour filter");
  if (input->GetDataObjectType() == VTK_UNSTRUCTURED_GRID)
    {
    vtkDebugMacro(<< "Processing unstructured grid");
    vtkContourGrid *cgrid;

    cgrid = vtkContourGrid::New();
    cgrid->SetInputData(input);
    // currently vtkContourGrid has a ComputeGradients option
    // but this doesn't do anything and will soon be deprecated.
    cgrid->SetComputeNormals(this->ComputeNormals);
    cgrid->SetComputeScalars(this->ComputeScalars);
    cgrid->SetOutputPointsPrecision(this->OutputPointsPrecision);
    cgrid->SetGenerateTriangles(this->GenerateTriangles);
    if ( this->Locator )
      {
      cgrid->SetLocator( this->Locator );
      }

    for (i = 0; i < numContours; i++)
      {
      cgrid->SetValue(i, values[i]);
      }
    cgrid->SetUpdateExtent(
      0,
      info->Get(vtkStreamingDemandDrivenPipeline::UPDATE_PIECE_NUMBER()),
      info->Get(vtkStreamingDemandDrivenPipeline:: UPDATE_NUMBER_OF_PIECES()),
      info->Get(vtkStreamingDemandDrivenPipeline::UPDATE_NUMBER_OF_GHOST_LEVELS()));
    cgrid->SetInputArrayToProcess(0,this->GetInputArrayInformation(0));
    cgrid->Update();
    output->ShallowCopy(cgrid->GetOutput());
    cgrid->Delete();
    } //if type VTK_UNSTRUCTURED_GRID
  else
    {
    numCells = input->GetNumberOfCells();
    inScalars = this->GetInputArrayToProcess(0,inputVector);
    if ( ! inScalars || numCells < 1 )
      {
      vtkDebugMacro(<<"No data to contour");
      return 1;
      }

    // Create objects to hold output of contour operation. First estimate
    // allocation size.
    //
    estimatedSize=
      static_cast<vtkIdType>(pow(static_cast<double>(numCells),.75));
    estimatedSize *= numContours;
    estimatedSize = estimatedSize / 1024 * 1024; //multiple of 1024
    if (estimatedSize < 1024)
      {
      estimatedSize = 1024;
      }

    newPts = vtkPoints::New();
    // set precision for the points in the output
    if(this->OutputPointsPrecision == vtkAlgorithm::DEFAULT_PRECISION)
      {
      vtkPointSet *inputPointSet = vtkPointSet::SafeDownCast(input);
      if(inputPointSet)
        {
        newPts->SetDataType(inputPointSet->GetPoints()->GetDataType());
        }
      }
    else if(this->OutputPointsPrecision == vtkAlgorithm::SINGLE_PRECISION)
      {
      newPts->SetDataType(VTK_FLOAT);
      }
    else if(this->OutputPointsPrecision == vtkAlgorithm::DOUBLE_PRECISION)
      {
      newPts->SetDataType(VTK_DOUBLE);
      }
    newPts->Allocate(estimatedSize,estimatedSize);
    newVerts = vtkCellArray::New();
    newVerts->Allocate(estimatedSize,estimatedSize);
    newLines = vtkCellArray::New();
    newLines->Allocate(estimatedSize,estimatedSize);
    newPolys = vtkCellArray::New();
    newPolys->Allocate(estimatedSize,estimatedSize);
    cellScalars = inScalars->NewInstance();
    cellScalars->SetNumberOfComponents(inScalars->GetNumberOfComponents());
    cellScalars->Allocate(cellScalars->GetNumberOfComponents()*VTK_CELL_SIZE);

    // locator used to merge potentially duplicate points
    if ( this->Locator == NULL )
      {
      this->CreateDefaultLocator();
      }
    this->Locator->InitPointInsertion (newPts,
                                       input->GetBounds(),estimatedSize);

    // interpolate data along edge
    // if we did not ask for scalars to be computed, don't copy them
    if (!this->ComputeScalars)
      {
      outPd->CopyScalarsOff();
      }
    outPd->InterpolateAllocate(inPd,estimatedSize,estimatedSize);
    outCd->CopyAllocate(inCd,estimatedSize,estimatedSize);

    vtkContourHelper helper(this->Locator, newVerts, newLines, newPolys,inPd, inCd, outPd,outCd, estimatedSize, this->GenerateTriangles!=0);
    // If enabled, build a scalar tree to accelerate search
    //
    if ( !this->UseScalarTree )
      {
      vtkGenericCell *cell = vtkGenericCell::New();
      // Three passes over the cells to process lower dimensional cells first.
      // For poly data output cells need to be added in the order:
      // verts, lines and then polys, or cell data gets mixed up.
      // A better solution is to have an unstructured grid output.
      // I create a table that maps cell type to cell dimensionality,
      // because I need a fast way to get cell dimensionality.
      // This assumes GetCell is slow and GetCellType is fast.
      // I do not like hard coding a list of cell types here,
      // but I do not want to add GetCellDimension(vtkIdType cellId)
      // to the vtkDataSet API.  Since I anticipate that the output
      // will change to vtkUnstructuredGrid.  This temporary solution
      // is acceptable.
      //
      int cellType;
      unsigned char cellTypeDimensions[VTK_NUMBER_OF_CELL_TYPES];
      vtkCutter::GetCellTypeDimensions(cellTypeDimensions);
      int dimensionality;
      // We skip 0d cells (points), because they cannot be cut (generate no data).
      for (dimensionality = 1; dimensionality <= 3; ++dimensionality)
        {
        // Loop over all cells; get scalar values for all cell points
        // and process each cell.
        //
        for (cellId=0; cellId < numCells && !abortExecute; cellId++)
          {
          // I assume that "GetCellType" is fast.
          cellType = input->GetCellType(cellId);
          if (cellType >= VTK_NUMBER_OF_CELL_TYPES)
            { // Protect against new cell types added.
            vtkErrorMacro("Unknown cell type " << cellType);
            continue;
            }
          if (cellTypeDimensions[cellType] != dimensionality)
            {
            continue;
            }
          input->GetCell(cellId,cell);
          cellPts = cell->GetPointIds();
          if (cellScalars->GetSize()/cellScalars->GetNumberOfComponents() <
            cellPts->GetNumberOfIds())
            {
            cellScalars->Allocate(
              cellScalars->GetNumberOfComponents()*cellPts->GetNumberOfIds());
            }
          inScalars->GetTuples(cellPts,cellScalars);

          if (dimensionality == 3 &&  ! (cellId % 5000) )
            {
            vtkDebugMacro(<<"Contouring #" << cellId);
            this->UpdateProgress (static_cast<double>(cellId)/numCells);
            abortExecute = this->GetAbortExecute();
            }

          for (i=0; i < numContours; i++)
            {
            helper.Contour(cell,values[i],cellScalars,cellId);
            } // for all contour values
          } // for all cells
        } // for all dimensions
      cell->Delete();
      } //if using scalar tree
    else
      {
      vtkCell *cell;
      if ( this->ScalarTree == NULL )
        {
        this->ScalarTree = vtkSimpleScalarTree::New();
        }
      this->ScalarTree->SetDataSet(input);
      // Note: This will have problems when input contains 2D and 3D cells.
      // CellData will get scrabled because of the implicit ordering of
      // verts, lines and polys in vtkPolyData.  The solution
      // is to convert this filter to create unstructured grid.
      //
      // Loop over all contour values.  Then for each contour value,
      // loop over all cells.
      //
      for (i=0; i < numContours; i++)
        {
        for ( this->ScalarTree->InitTraversal(values[i]);
              (cell=this->ScalarTree->GetNextCell(cellId,cellPts,cellScalars)) != NULL; )
          {
          helper.Contour(cell,values[i],cellScalars,cellId);
          } //for all cells
        } //for all contour values
      } //using scalar tree

    vtkDebugMacro(<<"Created: "
                  << newPts->GetNumberOfPoints() << " points, "
                  << newVerts->GetNumberOfCells() << " verts, "
                  << newLines->GetNumberOfCells() << " lines, "
                  << newPolys->GetNumberOfCells() << " triangles");

    // Update ourselves.  Because we don't know up front how many verts, lines,
    // polys we've created, take care to reclaim memory.
    //
    output->SetPoints(newPts);
    newPts->Delete();
    cellScalars->Delete();

    if (newVerts->GetNumberOfCells())
      {
      output->SetVerts(newVerts);
      }
    newVerts->Delete();

    if (newLines->GetNumberOfCells())
      {
      output->SetLines(newLines);
      }
    newLines->Delete();

    if (newPolys->GetNumberOfCells())
      {
      output->SetPolys(newPolys);
      }
    newPolys->Delete();

    this->Locator->Initialize();//releases leftover memory
    output->Squeeze();
    } //else if not vtkUnstructuredGrid

  return 1;
}

// Specify a spatial locator for merging points. By default,
// an instance of vtkMergePoints is used.
void vtkContourFilter::SetLocator(vtkIncrementalPointLocator *locator)
{
  if ( this->Locator == locator )
    {
    return;
    }
  if ( this->Locator )
    {
    this->Locator->UnRegister(this);
    this->Locator = NULL;
    }
  if ( locator )
    {
    locator->Register(this);
    }
  this->Locator = locator;
  this->Modified();
}

void vtkContourFilter::CreateDefaultLocator()
{
  if ( this->Locator == NULL )
    {
    this->Locator = vtkMergePoints::New();
    this->Locator->Register(this);
    this->Locator->Delete();
    }
}

void vtkContourFilter::SetArrayComponent( int comp )
{
  this->SynchronizedTemplates2D->SetArrayComponent( comp );
  this->SynchronizedTemplates3D->SetArrayComponent( comp );
  this->RectilinearSynchronizedTemplates->SetArrayComponent( comp );
}

int vtkContourFilter::GetArrayComponent()
{
  return( this->SynchronizedTemplates2D->GetArrayComponent() );
}

void vtkContourFilter::SetOutputPointsPrecision(int precision)
{
  this->OutputPointsPrecision = precision;
  this->Modified();
}

int vtkContourFilter::GetOutputPointsPrecision() const
{
  return this->OutputPointsPrecision;
}

//----------------------------------------------------------------------------
int vtkContourFilter::ProcessRequest(vtkInformation* request,
                                     vtkInformationVector** inputVector,
                                     vtkInformationVector* outputVector)
{
  // generate the data
  if(request->Has(vtkStreamingDemandDrivenPipeline::REQUEST_UPDATE_EXTENT_INFORMATION()))
    {
    // compute the priority for this UE
    vtkInformation *inInfo = inputVector[0]->GetInformationObject(0);
    vtkInformation *outInfo = outputVector->GetInformationObject(0);

    // get the range of the input if available
    vtkInformation *fInfo = NULL;
    vtkDataArray *inscalars = this->GetInputArrayToProcess(0, inputVector);
    if (inscalars)
      {
      vtkInformationVector *miv = inInfo->Get(vtkDataObject::POINT_DATA_VECTOR());
      for (int index = 0; index < miv->GetNumberOfInformationObjects(); index++)
        {
        vtkInformation *mInfo = miv->GetInformationObject(index);
        const char *minfo_arrayname =
          mInfo->Get(vtkDataObject::FIELD_ARRAY_NAME());
        if (minfo_arrayname && !strcmp(minfo_arrayname, inscalars->GetName()))
          {
          fInfo = mInfo;
          break;
          }
        }
      }
    else
      {
      fInfo = vtkDataObject::GetActiveFieldInformation
        (inInfo, vtkDataObject::FIELD_ASSOCIATION_POINTS,
         vtkDataSetAttributes::SCALARS);
      }

    if (!fInfo)
      {
      return 1;
      }

    double *range = fInfo->Get(vtkDataObject::PIECE_FIELD_RANGE());
    int numContours = this->ContourValues->GetNumberOfContours();
    if (range && numContours)
      {
      // compute the priority
      // get the incoming priority if any
      double inPriority = 1;
      if (inInfo->Has(vtkStreamingDemandDrivenPipeline::PRIORITY()))
        {
        inPriority = inInfo->Get(vtkStreamingDemandDrivenPipeline::PRIORITY());
        }
      outInfo->Set(vtkStreamingDemandDrivenPipeline::PRIORITY(),inPriority);
      if (!inPriority)
        {
        return 1;
        }

      // do any contours intersect the range?
      double *values=this->ContourValues->GetValues();
      int i;
      for (i=0; i < numContours; i++)
        {
        if (values[i] >= range[0] && values[i] <= range[1])
          {
          return 1;
          }
        }

      double inRes = 1.0;
      if (inInfo->Has(vtkStreamingDemandDrivenPipeline::UPDATE_RESOLUTION()))
        {
        inRes = inInfo->Get
          (vtkStreamingDemandDrivenPipeline::UPDATE_RESOLUTION());
        }
      if (inRes >= 0.99)
        {
        outInfo->Set(vtkStreamingDemandDrivenPipeline::PRIORITY(),0.0);
        }
      else
        {
        outInfo->Set
          (vtkStreamingDemandDrivenPipeline::PRIORITY(),inPriority*0.1);
        }
      }
    return 1;
    }
  return this->Superclass::ProcessRequest(request, inputVector, outputVector);
}

int vtkContourFilter::FillInputPortInformation(int, vtkInformation *info)
{
  info->Set(vtkAlgorithm::INPUT_REQUIRED_DATA_TYPE(), "vtkDataSet");
  return 1;
}

void vtkContourFilter::PrintSelf(ostream& os, vtkIndent indent)
{
  this->Superclass::PrintSelf(os,indent);

  os << indent << "Compute Gradients: "
     << (this->ComputeGradients ? "On\n" : "Off\n");
  os << indent << "Compute Normals: "
     << (this->ComputeNormals ? "On\n" : "Off\n");
  os << indent << "Compute Scalars: "
     << (this->ComputeScalars ? "On\n" : "Off\n");

  this->ContourValues->PrintSelf(os,indent.GetNextIndent());

  os << indent << "Use Scalar Tree: "
     << (this->UseScalarTree ? "On\n" : "Off\n");
  if ( this->ScalarTree )
    {
    os << indent << "Scalar Tree: " << this->ScalarTree << "\n";
    }
  else
    {
    os << indent << "Scalar Tree: (none)\n";
    }

  if ( this->Locator )
    {
    os << indent << "Locator: " << this->Locator << "\n";
    }
  else
    {
    os << indent << "Locator: (none)\n";
    }

  os << indent << "Precision of the output points: "
     << this->OutputPointsPrecision << "\n";
}

//----------------------------------------------------------------------------
void vtkContourFilter::ReportReferences(vtkGarbageCollector* collector)
{
  this->Superclass::ReportReferences(collector);
  // These filters share our input and are therefore involved in a
  // reference loop.
  vtkGarbageCollectorReport(collector, this->ScalarTree, "ScalarTree");
}
