// SPDX-FileCopyrightText: Copyright (c) Kitware Inc.
// SPDX-License-Identifier: BSD-3-Clause
#include "vtkPVGlyphFilter.h"

// VTK includes
#include "vtkBoundingBox.h"
#include "vtkCellCenters.h"
#include "vtkCellData.h"
#include "vtkCompositeDataIterator.h"
#include "vtkDataSet.h"
#include "vtkDataSetSurfaceFilter.h"
#include "vtkDataSetTriangleFilter.h"
#include "vtkFloatArray.h"
#include "vtkGenerateIds.h"
#include "vtkInformation.h"
#include "vtkInformationVector.h"
#include "vtkMinimalStandardRandomSequence.h"
#include "vtkMultiBlockDataSet.h"
#include "vtkMultiProcessController.h"
#include "vtkNew.h"
#include "vtkObjectFactory.h"
#include "vtkOctreePointLocator.h"
#include "vtkPointData.h"
#include "vtkPolyData.h"
#include "vtkSmartPointer.h"
#include "vtkStreamingDemandDrivenPipeline.h"
#include "vtkTetra.h"
#include "vtkTransform.h"
#include "vtkTriangle.h"
#include "vtkTriangleFilter.h"
#include "vtkTuple.h"
#include "vtkUniformGrid.h"
#include "vtkUniformGridAMR.h"
#include "vtkUnsignedCharArray.h"
#include "vtkUnstructuredGrid.h"

// C/C++ includes
#include <algorithm>
#include <cmath>
#include <map>
#include <numeric>
#include <random>
#include <set>
#include <vector>

static const std::string IDS_ARRAY_NAME = "vtkPVGlyphFilter_Ids";
class vtkPVGlyphFilter::vtkInternals
{
  vtkDataSet* LastDataSet = nullptr;

  // Used only with SPATIALLY_UNIFORM_DISTRIBUTION
  vtkBoundingBox Bounds;
  double NearestPointRadius;
  std::vector<vtkTuple<double, 3>> Points;
  std::vector<vtkIdType> PointIds;
  size_t NextPointId;
  vtkNew<vtkOctreePointLocator> Locator;

  // Used with SPATIALLY_UNIFORM_INVERSE_TRANSFORM_SAMPLING_*
  std::map<unsigned int, std::vector<double>> UniformSamplingVectorMap;
  std::vector<vtkIdType> IdLookupTable;
  double SamplingRunningSum = 0;

public:
  //---------------------------------------------------------------------------
  // Check that the ds have a correct size for the sampling
  // If not, use IDS_ARRAY_NAME to fill a id lookup table
  // Used only with SPATIALLY_UNIFORM_INVERSE_TRANSFORM_SAMPLING_*
  // Return true if lookup table was computed, false otherwise.
  bool ComputeIdLookupTable(vtkIdType samplingSize, vtkDataSet* ds, bool cellCenters)
  {
    this->IdLookupTable.resize(samplingSize);
    std::iota(this->IdLookupTable.begin(), this->IdLookupTable.end(), 0);
    vtkIdTypeArray* idArray = nullptr;
    vtkIdType nIds;
    if (cellCenters)
    {
      nIds = ds->GetNumberOfPoints();
      idArray = vtkIdTypeArray::SafeDownCast(ds->GetPointData()->GetArray(IDS_ARRAY_NAME.c_str()));
    }
    else
    {
      nIds = ds->GetNumberOfCells();
      idArray = vtkIdTypeArray::SafeDownCast(ds->GetCellData()->GetArray(IDS_ARRAY_NAME.c_str()));
    }
    if (nIds != samplingSize)
    {
      if (!idArray)
      {
        // This may happen with VTK_EMPTY_CELL in the input dataset
        // because of vtkCellCenters implementation
        return false;
      }
      for (vtkIdType i = 0; i < nIds; i++)
      {
        this->IdLookupTable[idArray->GetValue(i)] = i;
      }
    }
    return true;
  }

  //---------------------------------------------------------------------------
  // This will compute all visible points ahead of time if needed
  void ComputeVisiblePointsIfNeeded(
    unsigned int index, vtkDataSet* ds, bool cellCenters, vtkPVGlyphFilter* self)
  {
    int glyphMode = self->GetGlyphMode();
    if (glyphMode != vtkPVGlyphFilter::SPATIALLY_UNIFORM_DISTRIBUTION &&
      glyphMode != vtkPVGlyphFilter::SPATIALLY_UNIFORM_INVERSE_TRANSFORM_SAMPLING_SURFACE &&
      glyphMode != vtkPVGlyphFilter::SPATIALLY_UNIFORM_INVERSE_TRANSFORM_SAMPLING_VOLUME)
    {
      return; // nothing to do.
    }

    if (ds == this->LastDataSet)
    {
      return;
    }
    this->LastDataSet = ds;

    this->PointIds.clear();
    std::set<vtkIdType> pointIds;

    if (glyphMode == vtkPVGlyphFilter::SPATIALLY_UNIFORM_DISTRIBUTION)
    {
      this->Locator->Initialize();
      this->Locator->SetDataSet(ds);
      this->Locator->BuildLocator();

      for (auto iter : this->Points)
      {
        double dist2;
        vtkIdType ptId = this->Locator->FindClosestPointWithinRadius(
          this->NearestPointRadius, iter.GetData(), dist2);
        if (ptId >= 0)
        {
          pointIds.insert(ptId);
        }
      }
    }
    else
    {
      vtkNew<vtkIdList> cellPointIds;
      auto& uniformSamplingVector = this->UniformSamplingVectorMap[index];
      if (uniformSamplingVector.empty())
      {
        vtkErrorWithObjectMacro(self, "Could not find sampling vector");
        return;
      }

      if (!this->ComputeIdLookupTable(
            static_cast<vtkIdType>(uniformSamplingVector.size()), ds, cellCenters))
      {
        vtkWarningWithObjectMacro(
          self, "Provided dataset contain cells that can't be correctly sampled, ignored");
        return;
      }

      // From the local dataset contribution to the sampling, compute the number of points to sample
      double localSum = uniformSamplingVector.back();
      vtkIdType nLocalPoint =
        self->GetMaximumNumberOfSamplePoints() * localSum / this->SamplingRunningSum;

      std::mt19937 gen(self->GetSeed());
      std::uniform_real_distribution<> dis(0.0, localSum);
      for (vtkIdType n = 0; n < nLocalPoint; n++)
      {
        // The sampling vector being sorted, just find the index of the sampled cell
        double sample = dis(gen);
        auto it =
          std::upper_bound(uniformSamplingVector.begin(), uniformSamplingVector.end(), sample);

        if (cellCenters)
        {
          // With cell centers, points are located at the center of the sampled cells
          pointIds.insert(this->IdLookupTable[it - uniformSamplingVector.begin()]);
        }
        else
        {
          // Found a sampled cells, find any point from this cells that has not yet been added to
          // the visible points
          ds->GetCellPoints(this->IdLookupTable[it - uniformSamplingVector.begin()], cellPointIds);
          for (vtkIdType iPtId = 0; iPtId < cellPointIds->GetNumberOfIds(); iPtId++)
          {
            vtkIdType pointId = cellPointIds->GetId(iPtId);
            if (pointIds.insert(pointId).second)
            {
              break;
            }
            // If all points of the cells have already been added, do not add any point
          }
        }
      }
    }
    this->PointIds.insert(this->PointIds.begin(), pointIds.begin(), pointIds.end());
    this->NextPointId = 0;
  }

  //---------------------------------------------------------------------------
  void Reset()
  {
    this->LastDataSet = nullptr;

    this->Bounds.Reset();
    this->Points.clear();
    this->Locator->Initialize();
    this->Locator->SetDataSet(nullptr);

    this->UniformSamplingVectorMap.clear();
    this->SamplingRunningSum = 0;
  }

  //---------------------------------------------------------------------------
  vtkSmartPointer<vtkDataSet> UpdateWithDataset(
    unsigned int index, vtkDataSet* ds, vtkPVGlyphFilter* self)
  {
    assert(ds != nullptr && self != nullptr);

    vtkSmartPointer<vtkDataSet> dataSetToReturn = ds;

    int glyphMode = self->GetGlyphMode();
    switch (glyphMode)
    {
      case vtkPVGlyphFilter::SPATIALLY_UNIFORM_DISTRIBUTION:
        // collect local bounds information.
        double bds[6];
        ds->GetBounds(bds);
        if (vtkBoundingBox::IsValid(bds))
        {
          this->Bounds.AddBounds(bds);
        }
        break;
      case vtkPVGlyphFilter::SPATIALLY_UNIFORM_INVERSE_TRANSFORM_SAMPLING_SURFACE:
        VTK_FALLTHROUGH;
      case vtkPVGlyphFilter::SPATIALLY_UNIFORM_INVERSE_TRANSFORM_SAMPLING_VOLUME:
      {
        // No cells means no sampling possible
        if (ds->GetNumberOfCells() == 0)
        {
          return dataSetToReturn;
        }

        if (glyphMode == vtkPVGlyphFilter::SPATIALLY_UNIFORM_INVERSE_TRANSFORM_SAMPLING_SURFACE)
        {
          vtkPolyData* pd = vtkPolyData::SafeDownCast(ds);
          if (!pd)
          {
            // If dataset is not a PolyData, just extracts its surface so it will be used to sample
            // glyphs instead
            vtkNew<vtkDataSetSurfaceFilter> surface;
            surface->SetInputData(ds);
            surface->Update();
            dataSetToReturn = surface->GetOutput();
            ds = dataSetToReturn.Get();
          }
        }

        // Get a sampling vector from the map
        auto empRet = this->UniformSamplingVectorMap.emplace(std::piecewise_construct,
          std::make_tuple(index), std::make_tuple(ds->GetNumberOfCells(), 0.0));
        auto& uniformSamplingVector = empRet.first->second;

        // Add cell ids to the dataset in order to be able to recover the right cells later
        vtkNew<vtkGenerateIds> idFilter;
        idFilter->SetInputData(ds);
        idFilter->SetCellIdsArrayName(IDS_ARRAY_NAME);
        idFilter->PointIdsOff();
        idFilter->Update();
        dataSetToReturn = vtkDataSet::SafeDownCast(idFilter->GetOutput());
        ds = dataSetToReturn.Get();

        if (glyphMode == vtkPVGlyphFilter::SPATIALLY_UNIFORM_INVERSE_TRANSFORM_SAMPLING_SURFACE)
        {
          vtkNew<vtkTriangleFilter> triangleFilter;
          triangleFilter->SetInputData(ds);
          triangleFilter->PassLinesOff();
          triangleFilter->PassVertsOff();
          triangleFilter->Update();

          vtkPolyData* trianglePolyData = triangleFilter->GetOutput();
          vtkCellArray* triangleArray = trianglePolyData->GetPolys();

          vtkIdTypeArray* cellIdArray = vtkIdTypeArray::SafeDownCast(
            trianglePolyData->GetCellData()->GetArray(IDS_ARRAY_NAME.c_str()));
          if (!cellIdArray)
          {
            vtkErrorWithObjectMacro(self, "Could not find id array");
            return dataSetToReturn;
          }

          vtkIdType nPts;
          vtkIdType triangleId = 0;
          const vtkIdType* pts;
          for (triangleArray->InitTraversal(); triangleArray->GetNextCell(nPts, pts); triangleId++)
          {
            // Compute and stored in the sampling vector the area of each cell
            double p1[3];
            double p2[3];
            double p3[3];
            trianglePolyData->GetPoint(pts[0], p1);
            trianglePolyData->GetPoint(pts[1], p2);
            trianglePolyData->GetPoint(pts[2], p3);
            uniformSamplingVector[cellIdArray->GetValue(triangleId)] +=
              vtkTriangle::TriangleArea(p1, p2, p3);
          }
        }
        else // if (glyphMode ==
        // vtkPVGlyphFilter::SPATIALLY_UNIFORM_INVERSE_TRANSFORM_SAMPLING_VOLUME)
        {
          vtkNew<vtkDataSetTriangleFilter> tetraFilter;
          tetraFilter->SetInputData(ds);
          tetraFilter->TetrahedraOnlyOn();
          tetraFilter->Update();

          vtkUnstructuredGrid* tetraUG = tetraFilter->GetOutput();
          vtkCellArray* tetraArray = tetraUG->GetCells();

          vtkIdTypeArray* cellIdArray =
            vtkIdTypeArray::SafeDownCast(tetraUG->GetCellData()->GetArray(IDS_ARRAY_NAME.c_str()));
          if (!cellIdArray)
          {
            vtkErrorWithObjectMacro(self, "Could not find id array");
            return dataSetToReturn;
          }

          vtkIdType nPts;
          vtkIdType tetraId = 0;
          const vtkIdType* pts;
          for (tetraArray->InitTraversal(); tetraArray->GetNextCell(nPts, pts); tetraId++)
          {
            // Compute and stored in the sampling vector the volume of each cell
            double p1[3];
            double p2[3];
            double p3[3];
            double p4[3];
            tetraUG->GetPoint(pts[0], p1);
            tetraUG->GetPoint(pts[1], p2);
            tetraUG->GetPoint(pts[2], p3);
            tetraUG->GetPoint(pts[3], p4);
            uniformSamplingVector[cellIdArray->GetValue(tetraId)] +=
              std::abs(vtkTetra::ComputeVolume(p1, p2, p3, p4));
          }
        }
        // Compute a partial sum on the sampling vector in order to perform sampling later
        std::partial_sum(uniformSamplingVector.begin(), uniformSamplingVector.end(),
          uniformSamplingVector.begin());
        this->SamplingRunningSum += uniformSamplingVector.back();
      }
      break;
      default:
        break;
    }
    return dataSetToReturn;
  }

  //---------------------------------------------------------------------------
  void SynchronizeGlobalInformation(vtkPVGlyphFilter* self)
  {
    int glyphMode = self->GetGlyphMode();
    if (glyphMode != vtkPVGlyphFilter::SPATIALLY_UNIFORM_DISTRIBUTION &&
      glyphMode != vtkPVGlyphFilter::SPATIALLY_UNIFORM_INVERSE_TRANSFORM_SAMPLING_SURFACE &&
      glyphMode != vtkPVGlyphFilter::SPATIALLY_UNIFORM_INVERSE_TRANSFORM_SAMPLING_VOLUME)
    {
      return; // nothing to do.
    }

    if (glyphMode == vtkPVGlyphFilter::SPATIALLY_UNIFORM_DISTRIBUTION)
    {
      vtkMultiProcessController* controller = self->GetController();
      if (controller && controller->GetNumberOfProcesses() > 1)
      {
        double local_min[3] = { VTK_DOUBLE_MAX, VTK_DOUBLE_MAX, VTK_DOUBLE_MAX };
        double local_max[3] = { VTK_DOUBLE_MIN, VTK_DOUBLE_MIN, VTK_DOUBLE_MIN };
        if (this->Bounds.IsValid())
        {
          this->Bounds.GetMinPoint(local_min[0], local_min[1], local_min[2]);
          this->Bounds.GetMaxPoint(local_max[0], local_max[1], local_max[2]);
        }
        double global_min[3], global_max[3];

        controller->AllReduce(local_min, global_min, 3, vtkCommunicator::MIN_OP);
        controller->AllReduce(local_max, global_max, 3, vtkCommunicator::MAX_OP);

        this->Bounds.SetBounds(
          global_min[0], global_max[0], global_min[1], global_max[1], global_min[2], global_max[2]);
      }

      if (!this->Bounds.IsValid())
      {
        return;
      }

      // build up list of points to glyph.
      vtkNew<vtkMinimalStandardRandomSequence> randomGenerator;
      randomGenerator->SetSeed(self->GetSeed());
      this->Points.resize(self->GetMaximumNumberOfSamplePoints());
      for (vtkIdType cc = 0; cc < self->GetMaximumNumberOfSamplePoints(); cc++)
      {
        vtkTuple<double, 3>& tuple = this->Points[cc];
        randomGenerator->Next();
        tuple[0] = randomGenerator->GetRangeValue(
          this->Bounds.GetMinPoint()[0], this->Bounds.GetMaxPoint()[0]);
        randomGenerator->Next();
        tuple[1] = randomGenerator->GetRangeValue(
          this->Bounds.GetMinPoint()[1], this->Bounds.GetMaxPoint()[1]);
        randomGenerator->Next();
        tuple[2] = randomGenerator->GetRangeValue(
          this->Bounds.GetMinPoint()[2], this->Bounds.GetMaxPoint()[2]);
      }

      double l[3];
      this->Bounds.GetLengths(l);

      int dim = (l[0] > 0.0 && l[1] > 0.0 && l[2] > 0.0) ? 3 : 2;

      double volume = std::pow(this->Bounds.GetDiagonalLength(), dim);
      if (volume > 0.0)
      {
        assert(self->GetMaximumNumberOfSamplePoints() > 0);
        double volumePerGlyph = volume / self->GetMaximumNumberOfSamplePoints();
        double delta = std::pow(volumePerGlyph, 1.0 / dim);
        this->NearestPointRadius = delta / 2.0;
      }
      else
      {
        this->NearestPointRadius = 0.0001;
      }
    }
    else // if(glyphMode != vtkPVGlyphFilter::SPATIALLY_UNIFORM_INVERSE_TRANSFORM_SAMPLING_SURFACE
         // || glyphMode != vtkPVGlyphFilter::SPATIALLY_UNIFORM_INVERSE_TRANSFORM_SAMPLING_VOLUME)
    {
      // With inverse transform sampling, just sum the SamplingRunningSum
      vtkMultiProcessController* controller = self->GetController();
      if (controller && controller->GetNumberOfProcesses() > 1)
      {
        double localSum = this->SamplingRunningSum;
        controller->AllReduce(&localSum, &this->SamplingRunningSum, 1, vtkCommunicator::SUM_OP);
      }
    }
  }

  //---------------------------------------------------------------------------
  bool IsPointVisible(
    unsigned int index, vtkDataSet* ds, vtkIdType ptId, bool cellCenters, vtkPVGlyphFilter* self)
  {
    assert(ds != nullptr && self != nullptr);
    switch (self->GetGlyphMode())
    {
      case vtkPVGlyphFilter::ALL_POINTS:
        return true;

      case vtkPVGlyphFilter::EVERY_NTH_POINT:
        return self->GetStride() <= 1 || (ptId % self->GetStride()) == 0;

      case vtkPVGlyphFilter::SPATIALLY_UNIFORM_DISTRIBUTION:
        VTK_FALLTHROUGH;
      case vtkPVGlyphFilter::SPATIALLY_UNIFORM_INVERSE_TRANSFORM_SAMPLING_SURFACE:
        VTK_FALLTHROUGH;
      case vtkPVGlyphFilter::SPATIALLY_UNIFORM_INVERSE_TRANSFORM_SAMPLING_VOLUME:
        // This will initialize the needed structure and compute visible points
        // that should be glyphed.
        this->ComputeVisiblePointsIfNeeded(index, ds, cellCenters, self);

        // since PointIds is a sorted list, and we know that IsPointVisible will
        // be called for in monotonically increasing fashion for a specific ds, we
        // use this->NextPointId to simplify the "contains" check.

        while (
          (this->NextPointId < this->PointIds.size()) && (this->PointIds[this->NextPointId] < ptId))
        {
          // this is need since it is possible (due to ghost cells or other
          // masking employed by vtkGlyph3D) that certain ptIds are never tested
          // since they are rejected earlier on.
          this->NextPointId++;
        }

        if (this->NextPointId < this->PointIds.size() && ptId == this->PointIds[this->NextPointId])
        {
          this->NextPointId++;
          return true;
        }
    }
    return false;
  }
};

vtkStandardNewMacro(vtkPVGlyphFilter);
vtkCxxSetObjectMacro(vtkPVGlyphFilter, Controller, vtkMultiProcessController);
vtkCxxSetObjectMacro(vtkPVGlyphFilter, SourceTransform, vtkTransform);
//-----------------------------------------------------------------------------
vtkPVGlyphFilter::vtkPVGlyphFilter()
  : VectorScaleMode(SCALE_BY_MAGNITUDE)
  , SourceTransform(nullptr)
  , ScaleFactor(1.0)
  , GlyphMode(ALL_POINTS)
  , MaximumNumberOfSamplePoints(5000)
  , Seed(1)
  , Stride(1)
  , Controller(nullptr)
  , OutputPointsPrecision(vtkAlgorithm::DEFAULT_PRECISION)
  , Internals(new vtkPVGlyphFilter::vtkInternals())
{
  this->SetController(vtkMultiProcessController::GetGlobalController());
  this->SetNumberOfInputPorts(2);
}

//-----------------------------------------------------------------------------
vtkPVGlyphFilter::~vtkPVGlyphFilter()
{
  this->SetController(nullptr);
  this->SetSourceTransform(nullptr);
  delete this->Internals;
}

//----------------------------------------------------------------------------
// Specify a source object at a specified table location.
void vtkPVGlyphFilter::SetSourceConnection(int id, vtkAlgorithmOutput* algOutput)
{
  if (id < 0)
  {
    vtkErrorMacro("Bad index " << id << " for source.");
    return;
  }

  int numConnections = this->GetNumberOfInputConnections(1);
  if (id < numConnections)
  {
    this->SetNthInputConnection(1, id, algOutput);
  }
  else if (id == numConnections && algOutput)
  {
    this->AddInputConnection(1, algOutput);
  }
  else if (algOutput)
  {
    vtkWarningMacro("The source id provided is larger than the maximum "
                    "source id, using "
      << numConnections << " instead.");
    this->AddInputConnection(1, algOutput);
  }
}

//----------------------------------------------------------------------------
vtkMTimeType vtkPVGlyphFilter::GetMTime()
{
  vtkMTimeType mTime = this->Superclass::GetMTime();
  vtkMTimeType time;
  if (this->SourceTransform != nullptr)
  {
    time = this->SourceTransform->GetMTime();
    mTime = (time > mTime ? time : mTime);
  }
  return mTime;
}

//----------------------------------------------------------------------------
int vtkPVGlyphFilter::FillInputPortInformation(int port, vtkInformation* info)
{
  if (port == 0)
  {
    info->Set(vtkAlgorithm::INPUT_REQUIRED_DATA_TYPE(), "vtkDataSet");
    // we can handle composite datasets.
    info->Append(vtkAlgorithm::INPUT_REQUIRED_DATA_TYPE(), "vtkCompositeDataSet");
    return 1;
  }
  else if (port == 1)
  {
    info->Set(vtkAlgorithm::INPUT_IS_REPEATABLE(), 1);
    info->Set(vtkAlgorithm::INPUT_IS_OPTIONAL(), 1);
    info->Set(vtkAlgorithm::INPUT_REQUIRED_DATA_TYPE(), "vtkPolyData");
    return 1;
  }

  return 0;
}

//----------------------------------------------------------------------------
int vtkPVGlyphFilter::FillOutputPortInformation(int vtkNotUsed(port), vtkInformation* info)
{
  // now add our info
  info->Set(vtkDataObject::DATA_TYPE_NAME(), "vtkDataObject");
  return 1;
}

//----------------------------------------------------------------------------
int vtkPVGlyphFilter::ProcessRequest(
  vtkInformation* request, vtkInformationVector** inputVector, vtkInformationVector* outputVector)
{
  if (request->Has(vtkDemandDrivenPipeline::REQUEST_DATA_OBJECT()))
  {
    return this->RequestDataObject(request, inputVector, outputVector);
  }

  return this->Superclass::ProcessRequest(request, inputVector, outputVector);
}

//----------------------------------------------------------------------------
int vtkPVGlyphFilter::RequestDataObject(
  vtkInformation*, vtkInformationVector** inputVector, vtkInformationVector* outputVector)
{
  if (auto inputDT = vtkDataObjectTree::GetData(inputVector[0], 0))
  {
    auto output = vtkDataObjectTree::GetData(outputVector, 0);
    if (output == nullptr || !output->IsA(inputDT->GetClassName()))
    {
      auto clone = inputDT->NewInstance();
      outputVector->GetInformationObject(0)->Set(vtkDataObject::DATA_OBJECT(), clone);
      clone->FastDelete();
    }
  }
  else if (vtkUniformGridAMR::GetData(inputVector[0], 0))
  {
    // eventually, this will be PDC.
    auto output = vtkMultiBlockDataSet::GetData(outputVector, 0);
    if (!output)
    {
      output = vtkMultiBlockDataSet::New();
      outputVector->GetInformationObject(0)->Set(vtkDataObject::DATA_OBJECT(), output);
      output->FastDelete();
    }
  }
  else
  {
    vtkPolyData* pd = vtkPolyData::GetData(outputVector, 0);
    if (pd == nullptr)
    {
      pd = vtkPolyData::New();
      outputVector->GetInformationObject(0)->Set(vtkDataObject::DATA_OBJECT(), pd);
      pd->FastDelete();
    }
  }
  return 1;
}

//----------------------------------------------------------------------------
int vtkPVGlyphFilter::RequestData(vtkInformation* vtkNotUsed(request),
  vtkInformationVector** inputVector, vtkInformationVector* outputVector)
{
  vtkInformationVector* sourceVector = inputVector[1];

  this->Internals->Reset();

  vtkSmartPointer<vtkDataSet> ds = vtkDataSet::GetData(inputVector[0], 0);
  vtkCompositeDataSet* cds = vtkCompositeDataSet::GetData(inputVector[0], 0);
  if (ds)
  {
    ds = this->Internals->UpdateWithDataset(0, ds, this);
    this->Internals->SynchronizeGlobalInformation(this);

    if (!this->IsInputArrayToProcessValid(ds))
    {
      return 1;
    }

    vtkPolyData* outputPD = vtkPolyData::GetData(outputVector);
    assert(outputPD);
    const int result = this->Execute(0, ds, sourceVector, outputPD) ? 1 : 0;
    this->Internals->Reset();
    return result;
  }
  else if (cds)
  {
    auto outputDT = vtkDataObjectTree::GetData(outputVector);
    assert(outputDT != nullptr);
    outputDT->CopyStructure(cds);

    vtkSmartPointer<vtkDataObjectTree> cdsCopy;
    cdsCopy.TakeReference(outputDT->NewInstance());
    cdsCopy->CompositeShallowCopy(cds);

    vtkSmartPointer<vtkCompositeDataIterator> iter;
    iter.TakeReference(cdsCopy->NewIterator());
    for (iter->InitTraversal(); !iter->IsDoneWithTraversal(); iter->GoToNextItem())
    {
      vtkSmartPointer<vtkDataSet> current = vtkDataSet::SafeDownCast(iter->GetCurrentDataObject());
      if (current)
      {
        current = this->Internals->UpdateWithDataset(iter->GetCurrentFlatIndex(), current, this);
        cdsCopy->SetDataSet(iter, current);
      }
    }

    this->Internals->SynchronizeGlobalInformation(this);

    for (iter->InitTraversal(); !iter->IsDoneWithTraversal(); iter->GoToNextItem())
    {
      vtkDataSet* currentDS = vtkDataSet::SafeDownCast(iter->GetCurrentDataObject());
      if (currentDS)
      {
        if (!this->IsInputArrayToProcessValid(currentDS))
        {
          continue;
        }

        bool res;
        vtkNew<vtkPolyData> outputPD;
        res = this->Execute(
          iter->GetCurrentFlatIndex(), currentDS, sourceVector, outputPD.GetPointer());
        if (!res)
        {
          vtkErrorMacro("Glyph generation failed for block: " << iter->GetCurrentFlatIndex());
          this->Internals->Reset();
          return 0;
        }
        outputDT->SetDataSet(iter, outputPD.GetPointer());
      }
    }
  }
  this->Internals->Reset();
  return 1;
}

//-----------------------------------------------------------------------------
int vtkPVGlyphFilter::RequestUpdateExtent(vtkInformation* vtkNotUsed(request),
  vtkInformationVector** inputVector, vtkInformationVector* outputVector)
{
  // get the info objects
  vtkInformation* inInfo = inputVector[0]->GetInformationObject(0);
  vtkInformation* sourceInfo = inputVector[1]->GetInformationObject(0);
  vtkInformation* outInfo = outputVector->GetInformationObject(0);

  if (sourceInfo)
  {
    sourceInfo->Set(vtkStreamingDemandDrivenPipeline::UPDATE_PIECE_NUMBER(), 0);
    sourceInfo->Set(vtkStreamingDemandDrivenPipeline::UPDATE_NUMBER_OF_PIECES(), 1);
    sourceInfo->Set(vtkStreamingDemandDrivenPipeline::UPDATE_NUMBER_OF_GHOST_LEVELS(), 0);
  }
  inInfo->Set(vtkStreamingDemandDrivenPipeline::UPDATE_PIECE_NUMBER(),
    outInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_PIECE_NUMBER()));
  inInfo->Set(vtkStreamingDemandDrivenPipeline::UPDATE_NUMBER_OF_PIECES(),
    outInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_NUMBER_OF_PIECES()));
  inInfo->Set(vtkStreamingDemandDrivenPipeline::UPDATE_NUMBER_OF_GHOST_LEVELS(),
    outInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_NUMBER_OF_GHOST_LEVELS()));
  inInfo->Set(vtkStreamingDemandDrivenPipeline::EXACT_EXTENT(), 1);

  return 1;
}

//-----------------------------------------------------------------------------
int vtkPVGlyphFilter::IsPointVisible(
  unsigned int index, vtkDataSet* ds, vtkIdType ptId, bool cellCenters)
{
  return this->Internals->IsPointVisible(index, ds, ptId, cellCenters, this);
}

//-----------------------------------------------------------------------------
bool vtkPVGlyphFilter::IsInputArrayToProcessValid(vtkDataSet* input)
{
  vtkDataArray* scaleArray = this->GetInputArrayToProcess(0, input);
  vtkDataArray* orientationArray = this->GetInputArrayToProcess(1, input);
  int scaleArrayAssociation = this->GetInputArrayAssociation(0, input);
  int orientationArrayAssociation = this->GetInputArrayAssociation(1, input);
  if (scaleArrayAssociation != orientationArrayAssociation && scaleArray && orientationArray)
  {
    std::string scaleArrayType =
      (scaleArrayAssociation == vtkDataObject::FIELD_ASSOCIATION_POINTS ? "point" : "cell");
    std::string orientationArrayType =
      (orientationArrayAssociation == vtkDataObject::FIELD_ASSOCIATION_POINTS ? "point" : "cell");
    vtkWarningMacro(<< "Mismatched attributes:\n"
                    << scaleArray->GetName() << " is a " << scaleArrayType << " attribute whereas "
                    << orientationArray->GetName() << " is a " << orientationArrayType
                    << " attribute.");
    return false;
  }

  return true;
}

//----------------------------------------------------------------------------
vtkPolyData* vtkPVGlyphFilter::GetSource(int idx, vtkInformationVector* sourceInfo)
{
  vtkInformation* info = sourceInfo->GetInformationObject(idx);
  if (!info)
  {
    return nullptr;
  }
  return vtkPolyData::SafeDownCast(info->Get(vtkDataObject::DATA_OBJECT()));
}

//-----------------------------------------------------------------------------
bool vtkPVGlyphFilter::UseCellCenters(vtkDataSet* input)
{
  int inSScalarsAssociation = this->GetInputArrayAssociation(0, input);
  int inVectorsAssociation = this->GetInputArrayAssociation(1, input);
  return inSScalarsAssociation == vtkDataObject::FIELD_ASSOCIATION_CELLS ||
    inVectorsAssociation == vtkDataObject::FIELD_ASSOCIATION_CELLS;
}

//----------------------------------------------------------------------------
bool vtkPVGlyphFilter::Execute(
  unsigned int index, vtkDataSet* input, vtkInformationVector* sourceVector, vtkPolyData* output)
{
  if (this->UseCellCenters(input))
  {
    vtkNew<vtkCellCenters> cellCenters;
    cellCenters->SetInputData(input);
    cellCenters->Update();
    input = cellCenters->GetOutput();
    vtkDataArray* inSScalars = input->GetPointData()->GetArray(
      this->GetInputArrayInformation(0)->Get(vtkDataObject::FIELD_NAME()));
    vtkDataArray* inVectors = input->GetPointData()->GetArray(
      this->GetInputArrayInformation(1)->Get(vtkDataObject::FIELD_NAME()));
    return this->Execute(index, input, sourceVector, output, inSScalars, inVectors, true);
  }
  else
  {
    vtkDataArray* scaleArray = this->GetInputArrayToProcess(0, input);
    vtkDataArray* orientArray = this->GetInputArrayToProcess(1, input);
    return this->Execute(index, input, sourceVector, output, scaleArray, orientArray);
  }
}

//----------------------------------------------------------------------------
bool vtkPVGlyphFilter::Execute(unsigned int index, vtkDataSet* input,
  vtkInformationVector* sourceVector, vtkPolyData* output, vtkDataArray* scaleArray,
  vtkDataArray* orientArray, bool cellCenters)
{
  assert(input && output);
  if (input == nullptr || output == nullptr)
  {
    // nothing to do.
    return true;
  }

  if (orientArray && orientArray->GetNumberOfComponents() > 3)
  {
    vtkErrorMacro(<< "vtkDataArray " << orientArray->GetName() << " has more than 3 components.\n");
    return false;
  }

  vtkDebugMacro(<< "Generating glyphs");

  auto pts = vtkSmartPointer<vtkIdList>::New();
  pts->Allocate(VTK_CELL_SIZE);

  unsigned char* inGhostLevels = nullptr;
  vtkDataArray* temp = nullptr;
  auto pd = input->GetPointData();
  if (pd)
  {
    temp = pd->GetArray(vtkDataSetAttributes::GhostArrayName());
  }
  if ((!temp) || (temp->GetDataType() != VTK_UNSIGNED_CHAR) || (temp->GetNumberOfComponents() != 1))
  {
    vtkDebugMacro("No appropriate ghost levels field available.");
  }
  else
  {
    inGhostLevels = static_cast<vtkUnsignedCharArray*>(temp)->GetPointer(0);
  }

  vtkIdType numPts = input->GetNumberOfPoints();
  if (numPts < 1)
  {
    vtkDebugMacro(<< "No points to glyph!");
    return 1;
  }

  vtkSmartPointer<vtkPolyData> source = this->GetSource(0, sourceVector);
  if (source == nullptr)
  {
    vtkNew<vtkPolyData> defaultSource;
    defaultSource->Allocate();
    vtkNew<vtkPoints> defaultPoints;
    defaultPoints->Allocate(6);
    defaultPoints->InsertNextPoint(0, 0, 0);
    defaultPoints->InsertNextPoint(1, 0, 0);
    vtkIdType defaultPointIds[2];
    defaultPointIds[0] = 0;
    defaultPointIds[1] = 1;
    defaultSource->SetPoints(defaultPoints);
    defaultSource->InsertNextCell(VTK_LINE, 2, defaultPointIds);
    source = defaultSource;
  }

  auto sourcePts = source->GetPoints();
  vtkIdType numSourcePts = sourcePts->GetNumberOfPoints();
  vtkIdType numSourceCells = source->GetNumberOfCells();

  vtkDataArray* sourceNormals = source->GetPointData()->GetNormals();

  // Allocate storage for output point data
  vtkPointData* outputPD = output->GetPointData();
  outputPD->CopyNormalsOff();

  outputPD->CopyAllocate(pd, numPts * numSourcePts);

  vtkNew<vtkIdList> srcPointIdList;
  srcPointIdList->SetNumberOfIds(numSourcePts);
  vtkNew<vtkIdList> dstPointIdList;
  dstPointIdList->SetNumberOfIds(numSourcePts);
  vtkNew<vtkIdList> srcCellIdList;
  srcCellIdList->SetNumberOfIds(numSourceCells);
  vtkNew<vtkIdList> dstCellIdList;
  dstCellIdList->SetNumberOfIds(numSourceCells);

  auto newPts = vtkSmartPointer<vtkPoints>::New();

  // Set the desired precision for the points in the output.
  if (this->OutputPointsPrecision == vtkAlgorithm::DEFAULT_PRECISION)
  {
    newPts->SetDataType(VTK_FLOAT);
  }
  else if (this->OutputPointsPrecision == vtkAlgorithm::SINGLE_PRECISION)
  {
    newPts->SetDataType(VTK_FLOAT);
  }
  else if (this->OutputPointsPrecision == vtkAlgorithm::DOUBLE_PRECISION)
  {
    newPts->SetDataType(VTK_DOUBLE);
  }

  newPts->Allocate(numPts * numSourcePts);

  vtkSmartPointer<vtkFloatArray> newNormals;
  if (sourceNormals)
  {
    newNormals.TakeReference(vtkFloatArray::New());
    newNormals->SetNumberOfComponents(3);
    newNormals->Allocate(3 * numPts * numSourcePts);
    newNormals->SetName("Normals");
  }

  // Setting up for calls to PolyData::InsertNextCell()
  output->Allocate(source, 3 * numPts * numSourceCells, numPts * numSourceCells);

  vtkSmartPointer<vtkPoints> transformedSourcePts = vtkSmartPointer<vtkPoints>::New();
  transformedSourcePts->SetDataTypeToDouble();
  transformedSourcePts->Allocate(numSourcePts);

  // Traverse all Input points, transforming Source points and copying
  // point attributes.
  auto trans = vtkSmartPointer<vtkTransform>::New();
  vtkNew<vtkIdList> pointIdList;
  vtkIdType ptIncr = 0;
  for (vtkIdType inPtId = 0; inPtId < numPts; inPtId++)
  {
    double scalex(1.0), scaley(1.0), scalez(1.0);
    if (!(inPtId % 10000))
    {
      this->UpdateProgress(static_cast<double>(inPtId) / numPts);
      if (this->GetAbortExecute())
      {
        break;
      }
    }

    // Get the scalar and vector data
    if (scaleArray)
    {
      if (scaleArray->GetNumberOfComponents() == 1)
      {
        scalex = scaley = scalez = scaleArray->GetComponent(inPtId, 0);
      }
      else
      {
        // Consider the vector scaling mode
        if (scaleArray->GetNumberOfComponents() == 2)
        {
          double* vec2 = scaleArray->GetTuple(inPtId);
          if (this->VectorScaleMode == SCALE_BY_MAGNITUDE)
          {
            scalex = scaley = scalez = vtkMath::Norm2D(vec2);
          }
          else if (this->VectorScaleMode == SCALE_BY_COMPONENTS)
          {
            scalex = vec2[0];
            scaley = vec2[1];
            // leave scalez alone for 2D
          }
        }
        else if (scaleArray->GetNumberOfComponents() == 3)
        {
          double* vec3 = scaleArray->GetTuple(inPtId);
          if (this->VectorScaleMode == SCALE_BY_MAGNITUDE)
          {
            scalex = scaley = scalez = vtkMath::Norm(vec3);
          }
          else
          {
            scalex = vec3[0];
            scaley = vec3[1];
            scalez = vec3[2];
          }
        }
      }
    }

    // Apply scale factor
    scalex *= this->ScaleFactor;
    scaley *= this->ScaleFactor;
    scalez *= this->ScaleFactor;

    // Check ghost points.
    // If we are processing a piece, we do not want to duplicate
    // glyphs on the borders.
    if (inGhostLevels && inGhostLevels[inPtId] & vtkDataSetAttributes::DUPLICATEPOINT)
    {
      continue;
    }

    // this is used to respect blanking specified on uniform grids.
    vtkUniformGrid* inputUG = vtkUniformGrid::SafeDownCast(input);
    if (inputUG && !inputUG->IsPointVisible(inPtId))
    {
      // input is a vtkUniformGrid and the current point is blanked. Don't glyph
      // it.
      continue;
    }

    if (!this->IsPointVisible(index, input, inPtId, cellCenters))
    {
      continue;
    }

    // Now begin copying/transforming glyph
    trans->Identity();

    // Copy all topology (transformation independent)
    for (vtkIdType cellId = 0; cellId < numSourceCells; cellId++)
    {
      source->GetCellPoints(cellId, pointIdList);
      int npts = pointIdList->GetNumberOfIds();
      pts->Reset();
      for (vtkIdType i = 0; i < npts; i++)
      {
        pts->InsertId(i, pointIdList->GetId(i) + ptIncr);
      }
      output->InsertNextCell(source->GetCellType(cellId), pts);
    }

    // translate Source to Input point
    double x[3];
    input->GetPoint(inPtId, x);
    trans->Translate(x[0], x[1], x[2]);

    if (orientArray)
    {
      double v[3] = { 0.0 };
      orientArray->GetTuple(inPtId, v);
      double vMag = vtkMath::Norm(v);
      if (vMag > 0.0)
      {
        // if there is no y or z component
        if (v[1] == 0.0 && v[2] == 0.0)
        {
          if (v[0] < 0) // just flip x if we need to
          {
            trans->RotateWXYZ(180.0, 0, 1, 0);
          }
        }
        else
        {
          double vNew[3];
          vNew[0] = (v[0] + vMag) / 2.0;
          vNew[1] = v[1] / 2.0;
          vNew[2] = v[2] / 2.0;
          trans->RotateWXYZ(180.0, vNew[0], vNew[1], vNew[2]);
        }
      }
    }

    // scale data if appropriate
    if (scalex == 0.0)
    {
      scalex = 1.0e-10;
    }
    if (scaley == 0.0)
    {
      scaley = 1.0e-10;
    }
    if (scalez == 0.0)
    {
      scalez = 1.0e-10;
    }
    trans->Scale(scalex, scaley, scalez);

    // multiply points and normals by resulting matrix
    if (this->SourceTransform)
    {
      transformedSourcePts->Reset();
      this->SourceTransform->TransformPoints(sourcePts, transformedSourcePts);
      trans->TransformPoints(transformedSourcePts, newPts);
    }
    else
    {
      trans->TransformPoints(sourcePts, newPts);
    }

    if (newNormals.GetPointer())
    {
      trans->TransformNormals(sourceNormals, newNormals);
    }

    // Copy point data from source (if possible)
    if (pd)
    {
      for (vtkIdType i = 0; i < numSourcePts; ++i)
      {
        srcPointIdList->SetId(i, inPtId);
        dstPointIdList->SetId(i, ptIncr + i);
      }
      outputPD->CopyData(pd, srcPointIdList, dstPointIdList);
    }

    ptIncr += numSourcePts;
  }

  if (newNormals.GetPointer())
  {
    outputPD->SetNormals(newNormals);
  }

  // In certain cases, we can have a left over processing array, remove it.
  outputPD->RemoveArray(IDS_ARRAY_NAME.c_str());

  // Pass the field data
  output->GetFieldData()->PassData(input->GetFieldData());

  // Update ourselves and release memory
  //
  output->SetPoints(newPts);
  output->Squeeze();

  return true;
}

//-----------------------------------------------------------------------------
void vtkPVGlyphFilter::PrintSelf(ostream& os, vtkIndent indent)
{
  this->Superclass::PrintSelf(os, indent);
  os << indent << "GlyphMode: ";
  switch (this->GlyphMode)
  {
    case ALL_POINTS:
      os << "ALL_POINTS" << endl;
      break;

    case EVERY_NTH_POINT:
      os << "EVERY_NTH_POINT" << endl;
      break;

    case SPATIALLY_UNIFORM_DISTRIBUTION:
      os << "SPATIALLY_UNIFORM_DISTRIBUTION" << endl;
      break;

    case SPATIALLY_UNIFORM_INVERSE_TRANSFORM_SAMPLING_SURFACE:
      os << "SPATIALLY_UNIFORM_INVERSE_TRANSFORM_SAMPLING_SURFACE" << endl;
      break;

    case SPATIALLY_UNIFORM_INVERSE_TRANSFORM_SAMPLING_VOLUME:
      os << "SPATIALLY_UNIFORM_INVERSE_TRANSFORM_SAMPLING_VOLUME" << endl;
      break;

    default:
      os << "(invalid:" << this->GlyphMode << ")" << endl;
  }
  os << indent << "MaximumNumberOfSamplePoints: " << this->MaximumNumberOfSamplePoints << endl;
  os << indent << "Seed: " << this->Seed << endl;
  os << indent << "Stride: " << this->Stride << endl;
  os << indent << "Controller: " << this->Controller << endl;
}
