// SPDX-FileCopyrightText: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
// SPDX-License-Identifier: BSD-3-Clause
#include "vtkMapper.h"

#include "vtkAbstractArray.h"
#include "vtkCellData.h"
#include "vtkColorSeries.h"
#include "vtkCompositeDataSet.h"
#include "vtkDataArray.h"
#include "vtkDataObjectTreeIterator.h"
#include "vtkDataSet.h"
#include "vtkDataSetAttributes.h"
#include "vtkDoubleArray.h"
#include "vtkExecutive.h"
#include "vtkFieldData.h"
#include "vtkFloatArray.h"
#include "vtkImageData.h"
#include "vtkLookupTable.h"
#include "vtkMath.h"
#include "vtkPointData.h"
#include "vtkPolyData.h"
#include "vtkSelection.h"
#include "vtkUnsignedCharArray.h"
#include "vtkVariantArray.h"

// Initialize static member that controls global coincidence resolution
VTK_ABI_NAMESPACE_BEGIN
static int vtkMapperGlobalResolveCoincidentTopology = VTK_RESOLVE_OFF;
static double vtkMapperGlobalResolveCoincidentTopologyZShift = 0.01;
static int vtkMapperGlobalResolveCoincidentTopologyPolygonOffsetFaces = 1;

static double vtkMapperGlobalResolveCoincidentTopologyPolygonOffsetFactor = 0.0;
static double vtkMapperGlobalResolveCoincidentTopologyPolygonOffsetUnits = 0.0;
static double vtkMapperGlobalResolveCoincidentTopologyLineOffsetFactor = 0.0;
static double vtkMapperGlobalResolveCoincidentTopologyLineOffsetUnits = -4.0;
static double vtkMapperGlobalResolveCoincidentTopologyPointOffsetUnits = -8.0;

vtkCxxSetObjectMacro(vtkMapper, Selection, vtkSelection);

// Construct with initial range (0,1).
vtkMapper::vtkMapper()
  : ArrayName(nullptr)
{
  this->Colors = nullptr;
  this->Static = 0;
  this->LookupTable = nullptr;

  this->ScalarVisibility = 1;
  this->ScalarRange[0] = 0.0;
  this->ScalarRange[1] = 1.0;
  this->UseLookupTableScalarRange = 0;

  this->ColorMode = VTK_COLOR_MODE_DEFAULT;
  this->ScalarMode = VTK_SCALAR_MODE_DEFAULT;

  vtkMath::UninitializeBounds(this->Bounds);
  this->Center[0] = this->Center[1] = this->Center[2] = 0.0;

  this->RenderTime = 0.0;

  this->SetArrayName("");
  this->ArrayId = -1;
  this->ArrayComponent = 0;
  this->ArrayAccessMode = VTK_GET_ARRAY_BY_ID;

  this->FieldDataTupleId = -1;

  this->InterpolateScalarsBeforeMapping = 0;
  this->ColorCoordinates = nullptr;
  this->ColorTextureMap = nullptr;

  this->CoincidentPolygonFactor = 0.0;
  this->CoincidentPolygonOffset = 0.0;
  this->CoincidentLineFactor = 0.0;
  this->CoincidentLineOffset = 0.0;
  this->CoincidentPointOffset = 0.0;
}

vtkMapper::~vtkMapper()
{
  if (this->LookupTable)
  {
    this->LookupTable->UnRegister(this);
  }
  if (this->Colors != nullptr)
  {
    this->Colors->UnRegister(this);
  }
  if (this->ColorCoordinates != nullptr)
  {
    this->ColorCoordinates->UnRegister(this);
  }
  if (this->ColorTextureMap != nullptr)
  {
    this->ColorTextureMap->UnRegister(this);
  }
  this->SetArrayName(nullptr);
  this->SetSelection(nullptr);
}

// Get the bounds for the input of this mapper as
// (Xmin,Xmax,Ymin,Ymax,Zmin,Zmax).
double* vtkMapper::GetBounds()
{
  if (!this->Static)
  {
    this->Update();
  }
  vtkDataSet* input = this->GetInput();
  vtkPolyData* pd = vtkPolyData::SafeDownCast(input);
  if (!input)
  {
    vtkMath::UninitializeBounds(this->Bounds);
  }
  else if (pd)
  {
    pd->GetCellsBounds(this->Bounds);
  }
  else
  {
    input->GetBounds(this->Bounds);
  }
  return this->Bounds;
}

vtkDataSet* vtkMapper::GetInput()
{
  if (this->GetNumberOfInputConnections(0) < 1)
  {
    return nullptr;
  }
  return vtkDataSet::SafeDownCast(this->GetExecutive()->GetInputData(0, 0));
}

void vtkMapper::SetResolveCoincidentTopology(int val)
{
  if (val == vtkMapperGlobalResolveCoincidentTopology)
  {
    return;
  }
  vtkMapperGlobalResolveCoincidentTopology = val;
}

int vtkMapper::GetResolveCoincidentTopology()
{
  return vtkMapperGlobalResolveCoincidentTopology;
}

void vtkMapper::SetResolveCoincidentTopologyToDefault()
{
  vtkMapperGlobalResolveCoincidentTopology = VTK_RESOLVE_OFF;
}

void vtkMapper::SetResolveCoincidentTopologyZShift(double val)
{
  if (val == vtkMapperGlobalResolveCoincidentTopologyZShift)
  {
    return;
  }
  vtkMapperGlobalResolveCoincidentTopologyZShift = val;
}

double vtkMapper::GetResolveCoincidentTopologyZShift()
{
  return vtkMapperGlobalResolveCoincidentTopologyZShift;
}

void vtkMapper::SetResolveCoincidentTopologyPolygonOffsetParameters(double factor, double units)
{
  if (factor == vtkMapperGlobalResolveCoincidentTopologyPolygonOffsetFactor &&
    units == vtkMapperGlobalResolveCoincidentTopologyPolygonOffsetUnits)
  {
    return;
  }
  vtkMapperGlobalResolveCoincidentTopologyPolygonOffsetFactor = factor;
  vtkMapperGlobalResolveCoincidentTopologyPolygonOffsetUnits = units;
}

void vtkMapper::GetResolveCoincidentTopologyPolygonOffsetParameters(double& factor, double& units)
{
  factor = vtkMapperGlobalResolveCoincidentTopologyPolygonOffsetFactor;
  units = vtkMapperGlobalResolveCoincidentTopologyPolygonOffsetUnits;
}

void vtkMapper::SetRelativeCoincidentTopologyPolygonOffsetParameters(double factor, double units)
{
  if (factor == this->CoincidentPolygonFactor && units == this->CoincidentPolygonOffset)
  {
    return;
  }
  this->CoincidentPolygonFactor = factor;
  this->CoincidentPolygonOffset = units;
  this->Modified();
}

void vtkMapper::GetRelativeCoincidentTopologyPolygonOffsetParameters(double& factor, double& units)
{
  factor = this->CoincidentPolygonFactor;
  units = this->CoincidentPolygonOffset;
}

void vtkMapper::GetCoincidentTopologyPolygonOffsetParameters(double& factor, double& units)
{
  factor =
    vtkMapperGlobalResolveCoincidentTopologyPolygonOffsetFactor + this->CoincidentPolygonFactor;
  units =
    vtkMapperGlobalResolveCoincidentTopologyPolygonOffsetUnits + this->CoincidentPolygonOffset;
}

void vtkMapper::SetResolveCoincidentTopologyLineOffsetParameters(double factor, double units)
{
  if (factor == vtkMapperGlobalResolveCoincidentTopologyLineOffsetFactor &&
    units == vtkMapperGlobalResolveCoincidentTopologyLineOffsetUnits)
  {
    return;
  }
  vtkMapperGlobalResolveCoincidentTopologyLineOffsetFactor = factor;
  vtkMapperGlobalResolveCoincidentTopologyLineOffsetUnits = units;
}

void vtkMapper::GetResolveCoincidentTopologyLineOffsetParameters(double& factor, double& units)
{
  factor = vtkMapperGlobalResolveCoincidentTopologyLineOffsetFactor;
  units = vtkMapperGlobalResolveCoincidentTopologyLineOffsetUnits;
}

void vtkMapper::SetRelativeCoincidentTopologyLineOffsetParameters(double factor, double units)
{
  if (factor == this->CoincidentLineFactor && units == this->CoincidentLineOffset)
  {
    return;
  }
  this->CoincidentLineFactor = factor;
  this->CoincidentLineOffset = units;
  this->Modified();
}

void vtkMapper::GetRelativeCoincidentTopologyLineOffsetParameters(double& factor, double& units)
{
  factor = this->CoincidentLineFactor;
  units = this->CoincidentLineOffset;
}

void vtkMapper::GetCoincidentTopologyLineOffsetParameters(double& factor, double& units)
{
  factor = vtkMapperGlobalResolveCoincidentTopologyLineOffsetFactor + this->CoincidentLineFactor;
  units = vtkMapperGlobalResolveCoincidentTopologyLineOffsetUnits + this->CoincidentLineOffset;
}

void vtkMapper::SetResolveCoincidentTopologyPointOffsetParameter(double units)
{
  if (units == vtkMapperGlobalResolveCoincidentTopologyPointOffsetUnits)
  {
    return;
  }
  vtkMapperGlobalResolveCoincidentTopologyPointOffsetUnits = units;
}

void vtkMapper::GetResolveCoincidentTopologyPointOffsetParameter(double& units)
{
  units = vtkMapperGlobalResolveCoincidentTopologyPointOffsetUnits;
}

void vtkMapper::SetRelativeCoincidentTopologyPointOffsetParameter(double units)
{
  if (units == this->CoincidentPointOffset)
  {
    return;
  }
  this->CoincidentPointOffset = units;
  this->Modified();
}

void vtkMapper::GetRelativeCoincidentTopologyPointOffsetParameter(double& units)
{
  units = this->CoincidentPointOffset;
}

void vtkMapper::GetCoincidentTopologyPointOffsetParameter(double& units)
{
  units = vtkMapperGlobalResolveCoincidentTopologyPointOffsetUnits + this->CoincidentPointOffset;
}

void vtkMapper::SetResolveCoincidentTopologyPolygonOffsetFaces(int faces)
{
  vtkMapperGlobalResolveCoincidentTopologyPolygonOffsetFaces = faces;
}

int vtkMapper::GetResolveCoincidentTopologyPolygonOffsetFaces()
{
  return vtkMapperGlobalResolveCoincidentTopologyPolygonOffsetFaces;
}

// Overload standard modified time function. If lookup table is modified,
// then this object is modified as well.
vtkMTimeType vtkMapper::GetMTime()
{
  // vtkMTimeType mTime=this->MTime.GetMTime();
  vtkMTimeType mTime = vtkAbstractMapper::GetMTime();
  vtkMTimeType lutMTime;

  if (this->LookupTable != nullptr)
  {
    lutMTime = this->LookupTable->GetMTime();
    mTime = (lutMTime > mTime ? lutMTime : mTime);
  }

  return mTime;
}

void vtkMapper::ShallowCopy(vtkAbstractMapper* mapper)
{
  vtkMapper* m = vtkMapper::SafeDownCast(mapper);
  if (m != nullptr)
  {
    this->SetLookupTable(m->GetLookupTable());
    this->SetScalarVisibility(m->GetScalarVisibility());
    this->SetScalarRange(m->GetScalarRange());
    this->SetColorMode(m->GetColorMode());
    this->SetScalarMode(m->GetScalarMode());
    this->SetUseLookupTableScalarRange(m->GetUseLookupTableScalarRange());
    this->SetInterpolateScalarsBeforeMapping(m->GetInterpolateScalarsBeforeMapping());
    this->SetFieldDataTupleId(m->GetFieldDataTupleId());

    if (m->GetArrayAccessMode() == VTK_GET_ARRAY_BY_ID)
    {
      this->ColorByArrayComponent(m->GetArrayId(), m->GetArrayComponent());
    }
    else
    {
      this->ColorByArrayComponent(m->GetArrayName(), m->GetArrayComponent());
    }

    double f, u;
    m->GetRelativeCoincidentTopologyPolygonOffsetParameters(f, u);
    this->SetRelativeCoincidentTopologyPolygonOffsetParameters(f, u);

    m->GetRelativeCoincidentTopologyLineOffsetParameters(f, u);
    this->SetRelativeCoincidentTopologyLineOffsetParameters(f, u);

    m->GetRelativeCoincidentTopologyPointOffsetParameter(u);
    this->SetRelativeCoincidentTopologyPointOffsetParameter(u);
  }

  // Now do superclass
  this->vtkAbstractMapper3D::ShallowCopy(mapper);
}

// a side effect of this is that this->Colors is also set
// to the return value
vtkUnsignedCharArray* vtkMapper::MapScalars(double alpha)
{
  vtkDataSet* input = this->GetInput();
  int cellFlag; // not used
  return this->MapScalars(input, alpha, cellFlag);
}

// a side effect of this is that this->Colors is also set
// to the return value
vtkUnsignedCharArray* vtkMapper::MapScalars(double alpha, int& cellFlag)
{
  vtkDataSet* input = this->GetInput();
  return this->MapScalars(input, alpha, cellFlag);
}

//------------------------------------------------------------------------------
// Returns if we can use texture maps for scalar coloring. Note this doesn't say
// we "will" use scalar coloring. It says, if we do use scalar coloring, we will
// use a texture.
// When rendering multiblock datasets, if any 2 blocks provide different
// lookup tables for the scalars, then also we cannot use textures. This case can
// be handled if required.
int vtkMapper::CanUseTextureMapForColoring(vtkDataObject* input)
{
  if (!this->InterpolateScalarsBeforeMapping)
  {
    return 0; // user doesn't want us to use texture maps at all.
  }

  // index color does not use textures
  if (this->LookupTable && this->LookupTable->GetIndexedLookup())
  {
    return 0;
  }

  if (input->IsA("vtkDataSet"))
  {
    int cellFlag = 0;
    vtkDataSet* ds = static_cast<vtkDataSet*>(input);
    vtkDataArray* scalars = vtkAbstractMapper::GetScalars(
      ds, this->ScalarMode, this->ArrayAccessMode, this->ArrayId, this->ArrayName, cellFlag);

    if (!scalars)
    {
      // no scalars on this dataset, we don't care if texture is used at all.
      return 1;
    }

    if (cellFlag)
    {
      return 0; // cell data colors, don't use textures.
    }

    if ((this->ColorMode == VTK_COLOR_MODE_DEFAULT &&
          vtkArrayDownCast<vtkUnsignedCharArray>(scalars)) ||
      this->ColorMode == VTK_COLOR_MODE_DIRECT_SCALARS)
    {
      // Don't use texture is direct coloring using RGB unsigned chars is
      // requested.
      return 0;
    }
  }

  return 1;
}

vtkUnsignedCharArray* vtkMapper::MapScalars(vtkDataSet* input, double alpha)
{
  int cellFlag = 0;
  return this->MapScalars(input, alpha, cellFlag);
}

// a side effect of this is that this->Colors is also set
// to the return value
vtkUnsignedCharArray* vtkMapper::MapScalars(vtkDataSet* input, double alpha, int& cellFlag)
{
  vtkAbstractArray* scalars = vtkAbstractMapper::GetAbstractScalars(
    input, this->ScalarMode, this->ArrayAccessMode, this->ArrayId, this->ArrayName, cellFlag);

  // This is for a legacy feature: selection of the array component to color by
  // from the mapper.  It is now in the lookuptable.  When this feature
  // is removed, we can remove this condition.
  if (scalars == nullptr || scalars->GetNumberOfComponents() <= this->ArrayComponent)
  {
    this->ArrayComponent = 0;
  }

  if (!this->ScalarVisibility || scalars == nullptr || input == nullptr)
  { // No scalar colors.
    if (this->ColorCoordinates)
    {
      this->ColorCoordinates->UnRegister(this);
      this->ColorCoordinates = nullptr;
    }
    if (this->ColorTextureMap)
    {
      this->ColorTextureMap->UnRegister(this);
      this->ColorTextureMap = nullptr;
    }
    if (this->Colors)
    {
      this->Colors->UnRegister(this);
      this->Colors = nullptr;
    }
    return nullptr;
  }

  // Get the lookup table.
  vtkDataArray* dataArray = vtkArrayDownCast<vtkDataArray>(scalars);
  if (dataArray && dataArray->GetLookupTable())
  {
    this->SetLookupTable(dataArray->GetLookupTable());
  }
  else
  {
    // make sure we have a lookup table
    if (this->LookupTable == nullptr)
    {
      this->CreateDefaultLookupTable();
    }
    this->LookupTable->Build();
  }
  if (!this->UseLookupTableScalarRange)
  {
    this->LookupTable->SetRange(this->ScalarRange);
  }

  // Decide between texture color or vertex color.
  // Cell data always uses vertex color.
  // Only point data can use both texture and vertex coloring.
  if (this->CanUseTextureMapForColoring(input))
  {
    this->MapScalarsToTexture(scalars, alpha);
    return nullptr;
  }

  // Vertex colors are being used.
  // Get rid of texture Color arrays.  Only texture or vertex coloring
  // can be active at one time.  The existence of the array is the
  // signal to use that technique.
  if (this->ColorCoordinates)
  {
    this->ColorCoordinates->UnRegister(this);
    this->ColorCoordinates = nullptr;
  }
  if (this->ColorTextureMap)
  {
    this->ColorTextureMap->UnRegister(this);
    this->ColorTextureMap = nullptr;
  }

  // Lets try to reuse the old colors.
  if (this->Colors)
  {
    if (this->LookupTable && this->LookupTable->GetAlpha() == alpha)
    {
      if (this->GetMTime() < this->Colors->GetMTime() &&
        input->GetMTime() < this->Colors->GetMTime() &&
        this->LookupTable->GetMTime() < this->Colors->GetMTime())
      {
        return this->Colors;
      }
    }
  }

  // Get rid of old colors
  if (this->Colors)
  {
    this->Colors->UnRegister(this);
    this->Colors = nullptr;
  }

  // map scalars
  double orig_alpha = this->LookupTable->GetAlpha();
  this->LookupTable->SetAlpha(alpha);
  this->Colors = this->LookupTable->MapScalars(scalars, this->ColorMode, this->ArrayComponent);
  this->LookupTable->SetAlpha(orig_alpha);
  // Consistent register and unregisters
  this->Colors->Register(this);
  this->Colors->Delete();

  return this->Colors;
}

void vtkMapper::SelectColorArray(int arrayNum)
{
  this->ColorByArrayComponent(arrayNum, -1);
}

void vtkMapper::SelectColorArray(const char* arrayName)
{
  this->ColorByArrayComponent(arrayName, -1);
}

void vtkMapper::ColorByArrayComponent(int arrayNum, int component)
{
  if (this->ArrayId == arrayNum && component == this->ArrayComponent &&
    this->ArrayAccessMode == VTK_GET_ARRAY_BY_ID)
  {
    return;
  }
  this->Modified();

  this->ArrayId = arrayNum;
  this->ArrayComponent = component;
  this->ArrayAccessMode = VTK_GET_ARRAY_BY_ID;
}

void vtkMapper::ColorByArrayComponent(const char* arrayName, int component)
{
  if (!arrayName ||
    (strcmp(this->ArrayName, arrayName) == 0 && component == this->ArrayComponent &&
      this->ArrayAccessMode == VTK_GET_ARRAY_BY_NAME))
  {
    return;
  }
  this->Modified();

  this->SetArrayName(arrayName);
  this->ArrayComponent = component;
  this->ArrayAccessMode = VTK_GET_ARRAY_BY_NAME;
}

// Specify a lookup table for the mapper to use.
void vtkMapper::SetLookupTable(vtkScalarsToColors* lut)
{
  if (this->LookupTable != lut)
  {
    if (this->LookupTable)
    {
      this->LookupTable->UnRegister(this);
    }
    this->LookupTable = lut;
    if (lut)
    {
      lut->Register(this);
    }
    this->Modified();
  }
}

vtkScalarsToColors* vtkMapper::GetLookupTable()
{
  if (this->LookupTable == nullptr)
  {
    this->CreateDefaultLookupTable();
  }
  return this->LookupTable;
}

void vtkMapper::CreateDefaultLookupTable()
{
  if (this->LookupTable)
  {
    this->LookupTable->UnRegister(this);
  }
  vtkLookupTable* table = vtkLookupTable::New();
  this->LookupTable = table;
  this->LookupTable->Register(this);
  this->LookupTable->Delete();

  int cellFlag = 0; // not used
  vtkAbstractArray* abstractArray = vtkAbstractMapper::GetAbstractScalars(this->GetInput(),
    this->ScalarMode, this->ArrayAccessMode, this->ArrayId, this->ArrayName, cellFlag);

  vtkDataArray* dataArray = vtkArrayDownCast<vtkDataArray>(abstractArray);
  if (abstractArray && !dataArray)
  {
    // Use indexed lookup for non-numeric arrays
    this->LookupTable->IndexedLookupOn();

    // Get prominent values from array and set them up as annotations in the color map.
    vtkVariantArray* prominentValues = vtkVariantArray::New();
    abstractArray->GetProminentComponentValues(0, prominentValues);
    vtkIdType numProminentValues = prominentValues->GetNumberOfValues();
    table->SetNumberOfTableValues(numProminentValues);
    for (vtkIdType i = 0; i < numProminentValues; ++i)
    {
      vtkVariant& variant = prominentValues->GetValue(i);
      this->LookupTable->SetAnnotation(variant, variant.ToString());
    }
    prominentValues->Delete();

    // Set colors for annotations
    vtkColorSeries* colorSeries = vtkColorSeries::New();
    colorSeries->SetColorScheme(vtkColorSeries::BREWER_QUALITATIVE_PAIRED);
    colorSeries->BuildLookupTable(table, vtkColorSeries::CATEGORICAL);
    colorSeries->Delete();
  }
}

//-------------------------------------------------------------------
// Return the method of coloring scalar data.
const char* vtkMapper::GetColorModeAsString()
{
  if (this->ColorMode == VTK_COLOR_MODE_MAP_SCALARS)
  {
    return "MapScalars";
  }
  else
  {
    return "Default";
  }
}

// Return the method for obtaining scalar data.
const char* vtkMapper::GetScalarModeAsString()
{
  if (this->ScalarMode == VTK_SCALAR_MODE_USE_CELL_DATA)
  {
    return "UseCellData";
  }
  else if (this->ScalarMode == VTK_SCALAR_MODE_USE_POINT_DATA)
  {
    return "UsePointData";
  }
  else if (this->ScalarMode == VTK_SCALAR_MODE_USE_POINT_FIELD_DATA)
  {
    return "UsePointFieldData";
  }
  else if (this->ScalarMode == VTK_SCALAR_MODE_USE_CELL_FIELD_DATA)
  {
    return "UseCellFieldData";
  }
  else if (this->ScalarMode == VTK_SCALAR_MODE_USE_FIELD_DATA)
  {
    return "UseFieldData";
  }
  else
  {
    return "Default";
  }
}

//------------------------------------------------------------------------------
bool vtkMapper::HasOpaqueGeometry()
{
  // by default we only return true for Opaque or Translucent
  // not both.
  return !this->HasTranslucentPolygonalGeometry();
}

//------------------------------------------------------------------------------
bool vtkMapper::HasTranslucentPolygonalGeometry()
{
  // scalar visibility?
  int cellFlag = 0;
  vtkDataSet* input = this->GetInput();
  if (!input)
  {
    return false;
  }
  vtkAbstractArray* abstractArray = vtkAbstractMapper::GetAbstractScalars(
    input, this->ScalarMode, this->ArrayAccessMode, this->ArrayId, this->ArrayName, cellFlag);
  if (!this->ScalarVisibility || abstractArray == nullptr)
  { // No scalar colors.
    return false;
  }

  unsigned char ghostsToSkip;
  vtkUnsignedCharArray* ghosts =
    vtkAbstractMapper::GetGhostArray(input, this->ScalarMode, ghostsToSkip);

  vtkScalarsToColors* lut = this->GetLookupTable();
  if (lut)
  {
    // Ensure that the lookup table is built
    lut->Build();
    return (lut->IsOpaque(
              abstractArray, this->ColorMode, this->ArrayComponent, ghosts, ghostsToSkip) == 0);
  }

  return false;
}

// anonymous namespace
namespace
{

//------------------------------------------------------------------------------
template <class T>
void ScalarToTextureCoordinate(T scalar_value, // Input scalar
  double range_min,                            // range[0]
  double inv_range_width,                      // 1/(range[1]-range[0])
  float& tex_coord_s,                          // 1st tex coord
  float& tex_coord_t)                          // 2nd tex coord
{
  if (vtkMath::IsNan(scalar_value))
  {
    tex_coord_s = 0.5; // Scalar value is arbitrary when NaN
    tex_coord_t = 1.0; // 1.0 in t coordinate means NaN
  }
  else
  {
    // 0.0 in t coordinate means not NaN.  So why am I setting it to 0.49?
    // Because when you are mapping scalars and you have a NaN adjacent to
    // anything else, the interpolation everywhere should be NaN.  Thus, I
    // want the NaN color everywhere except right on the non-NaN neighbors.
    // To simulate this, I set the t coord for the real numbers close to
    // the threshold so that the interpolation almost immediately looks up
    // the NaN value.
    tex_coord_t = 0.49;

    double ranged_scalar = (scalar_value - range_min) * inv_range_width;
    tex_coord_s = static_cast<float>(ranged_scalar);
  }

  // Some implementations apparently don't handle relatively large
  // numbers (compared to the range [0.0, 1.0]) very well. In fact,
  // values above 1122.0f appear to cause texture wrap-around on
  // some systems even when edge clamping is enabled. Why 1122.0f? I
  // don't know. For safety, we'll clamp at +/- 1000. This will
  // result in incorrect images when the texture value should be
  // above or below 1000, but I don't have a better solution.
  if (tex_coord_s > 1000.0f)
  {
    tex_coord_s = 1000.0f;
  }
  else if (tex_coord_s < -1000.0f)
  {
    tex_coord_s = -1000.0f;
  }
}

//------------------------------------------------------------------------------
template <class T>
void CreateColorTextureCoordinates(T* input, float* output, vtkIdType numScalars, int numComps,
  int component, double* range, const double* table_range, int tableNumberOfColors,
  bool use_log_scale)
{
  // We have to change the range used for computing texture
  // coordinates slightly to accommodate the special above- and
  // below-range colors that are the first and last texels,
  // respectively.
  double scalar_texel_width = (range[1] - range[0]) / static_cast<double>(tableNumberOfColors);
  double padded_range[2];
  padded_range[0] = range[0] - scalar_texel_width;
  padded_range[1] = range[1] + scalar_texel_width;
  double inv_range_width = 1.0 / (padded_range[1] - padded_range[0]);

  if (component < 0 || component >= numComps)
  {
    for (vtkIdType scalarIdx = 0; scalarIdx < numScalars; ++scalarIdx)
    {
      double sum = 0;
      for (int compIdx = 0; compIdx < numComps; ++compIdx)
      {
        double tmp = static_cast<double>(*input);
        sum += (tmp * tmp);
        ++input;
      }
      double magnitude = sqrt(sum);
      if (use_log_scale)
      {
        magnitude = vtkLookupTable::ApplyLogScale(magnitude, table_range, range);
      }
      ScalarToTextureCoordinate(magnitude, padded_range[0], inv_range_width, output[0], output[1]);
      output += 2;
    }
  }
  else
  {
    input += component;
    for (vtkIdType scalarIdx = 0; scalarIdx < numScalars; ++scalarIdx)
    {
      double input_value = static_cast<double>(*input);
      if (use_log_scale)
      {
        input_value = vtkLookupTable::ApplyLogScale(input_value, table_range, range);
      }
      ScalarToTextureCoordinate(
        input_value, padded_range[0], inv_range_width, output[0], output[1]);
      output += 2;
      input = input + numComps;
    }
  }
}

} // end anonymous namespace

// a side effect of this is that this->ColorCoordinates and
// this->ColorTexture are set.
void vtkMapper::MapScalarsToTexture(vtkAbstractArray* scalars, double alpha)
{
  double range[2];
  range[0] = this->LookupTable->GetRange()[0];
  range[1] = this->LookupTable->GetRange()[1];
  bool use_log_scale = (this->LookupTable->UsingLogScale() != 0);
  if (use_log_scale)
  {
    // convert range to log.
    vtkLookupTable::GetLogRange(range, range);
  }

  double orig_alpha = this->LookupTable->GetAlpha();

  // Get rid of vertex color array.  Only texture or vertex coloring
  // can be active at one time.  The existence of the array is the
  // signal to use that technique.
  if (this->Colors)
  {
    this->Colors->UnRegister(this);
    this->Colors = nullptr;
  }

  // If the lookup table has changed, the recreate the color texture map.
  // Set a new lookup table changes this->MTime.
  if (this->ColorTextureMap == nullptr || this->GetMTime() > this->ColorTextureMap->GetMTime() ||
    this->LookupTable->GetMTime() > this->ColorTextureMap->GetMTime() ||
    this->LookupTable->GetAlpha() != alpha)
  {
    this->LookupTable->SetAlpha(alpha);
    if (this->ColorTextureMap)
    {
      this->ColorTextureMap->UnRegister(this);
      this->ColorTextureMap = nullptr;
    }
    // Get the texture map from the lookup table.
    // Create a dummy ramp of scalars.
    // In the future, we could extend vtkScalarsToColors.
    vtkIdType numberOfColors = this->LookupTable->GetNumberOfAvailableColors();
    numberOfColors += 2;
    // number of available colors can return 2^24
    // which is an absurd size for a tmap in this case. So we
    // watch for cases like that and reduce it to a
    // more reasonable size
    if (numberOfColors > 65538) // 65536+2
    {
      numberOfColors = 8192;
    }
    double k = (range[1] - range[0]) / (numberOfColors - 2);
    vtkDoubleArray* tmp = vtkDoubleArray::New();
    tmp->SetNumberOfTuples(numberOfColors * 2);
    double* ptr = tmp->GetPointer(0);
    for (int i = 0; i < numberOfColors; ++i)
    {
      *ptr = range[0] + i * k - k / 2.0; // minus k / 2 to start at below range color
      if (use_log_scale)
      {
        *ptr = pow(10.0, *ptr);
      }
      ++ptr;
    }
    // Dimension on NaN.
    double nan = vtkMath::Nan();
    for (int i = 0; i < numberOfColors; ++i)
    {
      *ptr = nan;
      ++ptr;
    }
    this->ColorTextureMap = vtkImageData::New();
    this->ColorTextureMap->SetExtent(0, numberOfColors - 1, 0, 1, 0, 0);
    this->ColorTextureMap->GetPointData()->SetScalars(
      this->LookupTable->MapScalars(tmp, this->ColorMode, 0));
    this->LookupTable->SetAlpha(orig_alpha);
    // Do we need to delete the scalars?
    this->ColorTextureMap->GetPointData()->GetScalars()->Delete();
    // Consistent register and unregisters
    this->ColorTextureMap->Register(this);
    this->ColorTextureMap->Delete();
    tmp->Delete();
  }

  // Create new coordinates if necessary.
  // Need to compare lookup table in case the range has changed.
  if (this->ColorCoordinates == nullptr || this->GetMTime() > this->ColorCoordinates->GetMTime() ||
    this->GetExecutive()->GetInputData(0, 0)->GetMTime() > this->ColorCoordinates->GetMTime() ||
    this->LookupTable->GetMTime() > this->ColorCoordinates->GetMTime())
  {
    // Get rid of old colors
    if (this->ColorCoordinates)
    {
      this->ColorCoordinates->UnRegister(this);
      this->ColorCoordinates = nullptr;
    }

    // Now create the color texture coordinates.
    int numComps = scalars->GetNumberOfComponents();
    void* input = scalars->GetVoidPointer(0);
    vtkIdType num = scalars->GetNumberOfTuples();
    this->ColorCoordinates = vtkFloatArray::New();
    this->ColorCoordinates->SetNumberOfComponents(2);
    this->ColorCoordinates->SetNumberOfTuples(num);
    float* output = this->ColorCoordinates->GetPointer(0);
    int scalarComponent;
    // Although I like the feature of applying magnitude to single component
    // scalars, it is not how the old MapScalars for vertex coloring works.
    if (this->LookupTable->GetVectorMode() == vtkScalarsToColors::MAGNITUDE &&
      scalars->GetNumberOfComponents() > 1)
    {
      scalarComponent = -1;
    }
    else
    {
      scalarComponent = this->LookupTable->GetVectorComponent();
    }
    switch (scalars->GetDataType())
    {
      vtkTemplateMacro(CreateColorTextureCoordinates(static_cast<VTK_TT*>(input), output, num,
        numComps, scalarComponent, range, this->LookupTable->GetRange(),
        this->LookupTable->GetNumberOfAvailableColors(), use_log_scale));
      case VTK_BIT:
        vtkErrorMacro("Cannot color by bit array.");
        break;
      default:
        vtkErrorMacro(<< "Unknown input ScalarType");
        return;
    }
  }
}

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

  if (this->LookupTable)
  {
    os << indent << "Lookup Table:\n";
    this->LookupTable->PrintSelf(os, indent.GetNextIndent());
  }
  else
  {
    os << indent << "Lookup Table: (none)\n";
  }

  os << indent << "Scalar Visibility: " << (this->ScalarVisibility ? "On\n" : "Off\n");

  os << indent << "Static: " << (this->Static ? "On\n" : "Off\n");

  double* range = this->GetScalarRange();
  os << indent << "Scalar Range: (" << range[0] << ", " << range[1] << ")\n";

  os << indent << "UseLookupTableScalarRange: " << this->UseLookupTableScalarRange << "\n";

  os << indent << "Color Mode: " << this->GetColorModeAsString() << endl;
  os << indent << "InterpolateScalarsBeforeMapping: "
     << (this->InterpolateScalarsBeforeMapping ? "On\n" : "Off\n");

  os << indent << "Scalar Mode: " << this->GetScalarModeAsString() << endl;

  os << indent << "RenderTime: " << this->RenderTime << endl;

  os << indent << "Resolve Coincident Topology: ";
  if (vtkMapperGlobalResolveCoincidentTopology == VTK_RESOLVE_OFF)
  {
    os << "Off" << endl;
  }
  else if (vtkMapperGlobalResolveCoincidentTopology == VTK_RESOLVE_POLYGON_OFFSET)
  {
    os << "Polygon Offset" << endl;
  }
  else
  {
    os << "Shift Z-Buffer" << endl;
  }

  os << indent << "CoincidentPointOffset: " << this->CoincidentPointOffset << "\n";
  os << indent << "CoincidentLineOffset: " << this->CoincidentLineOffset << "\n";
  os << indent << "CoincidentPolygonOffset: " << this->CoincidentPolygonOffset << "\n";
  os << indent << "CoincidentLineFactor: " << this->CoincidentLineFactor << "\n";
  os << indent << "CoincidentPolygonFactor: " << this->CoincidentPolygonFactor << "\n";
}

//-------------------------------------------------------------------
void vtkMapper::ClearColorArrays()
{
  if (this->Colors)
  {
    this->Colors->Delete();
    this->Colors = nullptr;
  }
  if (this->ColorCoordinates)
  {
    this->ColorCoordinates->Delete();
    this->ColorCoordinates = nullptr;
  }
  if (this->ColorTextureMap)
  {
    this->ColorTextureMap->Delete();
    this->ColorTextureMap = nullptr;
  }
}

//-------------------------------------------------------------------
vtkUnsignedCharArray* vtkMapper::GetColorMapColors()
{
  return this->Colors;
}

//-------------------------------------------------------------------
vtkFloatArray* vtkMapper::GetColorCoordinates()
{
  return this->ColorCoordinates;
}

//-------------------------------------------------------------------
vtkImageData* vtkMapper::GetColorTextureMap()
{
  return this->ColorTextureMap;
}
VTK_ABI_NAMESPACE_END
