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

  Program:   Visualization Toolkit
  Module:    vtkTubeFilter.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 "vtkTubeFilter.h"

#include "vtkCellArray.h"
#include "vtkCellData.h"
#include "vtkFloatArray.h"
#include "vtkInformation.h"
#include "vtkInformationVector.h"
#include "vtkMath.h"
#include "vtkObjectFactory.h"
#include "vtkPointData.h"
#include "vtkPolyData.h"
#include "vtkPolyLine.h"

#include <algorithm>

vtkStandardNewMacro(vtkTubeFilter);

// Construct object with radius 0.5, radius variation turned off, the number
// of sides set to 3, and radius factor of 10.
vtkTubeFilter::vtkTubeFilter()
{
  this->Radius = 0.5;
  this->VaryRadius = VTK_VARY_RADIUS_OFF;
  this->NumberOfSides = 3;
  this->RadiusFactor = 10;

  this->DefaultNormal[0] = this->DefaultNormal[1] = 0.0;
  this->DefaultNormal[2] = 1.0;

  this->UseDefaultNormal = 0;
  this->SidesShareVertices = 1;
  this->Capping = 0;
  this->OnRatio = 1;
  this->Offset = 0;

  this->GenerateTCoords = VTK_TCOORDS_OFF;
  this->TextureLength = 1.0;

  this->OutputPointsPrecision = vtkAlgorithm::DEFAULT_PRECISION;

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

  // by default process active point vectors
  this->SetInputArrayToProcess(
    1, 0, 0, vtkDataObject::FIELD_ASSOCIATION_POINTS, vtkDataSetAttributes::VECTORS);
}

namespace
{

struct IdPointsEqual
{
  IdPointsEqual(vtkPoints* points)
    : Points(points)
  {
  }

  bool operator()(vtkIdType id1, vtkIdType id2) const
  {
    double p1[3], p2[3];
    this->Points->GetPoint(id1, p1);
    this->Points->GetPoint(id2, p2);
    return (p1[0] == p2[0] && p1[1] == p2[1] && p1[2] == p2[2]);
  }

  vtkPoints* Points;
};

}

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

  // get the input and output
  vtkPolyData* input = vtkPolyData::SafeDownCast(inInfo->Get(vtkDataObject::DATA_OBJECT()));
  vtkPolyData* output = vtkPolyData::SafeDownCast(outInfo->Get(vtkDataObject::DATA_OBJECT()));

  vtkPointData* pd = input->GetPointData();
  vtkPointData* outPD = output->GetPointData();
  vtkCellData* cd = input->GetCellData();
  vtkCellData* outCD = output->GetCellData();
  vtkCellArray* inLines;
  vtkDataArray* inNormals;
  vtkDataArray* inScalars = this->GetInputArrayToProcess(0, inputVector);
  vtkDataArray* inVectors = this->GetInputArrayToProcess(1, inputVector);

  vtkPoints* inPts;
  vtkIdType numPts;
  vtkIdType numLines;
  vtkIdType numNewPts, numNewCells;
  vtkPoints* newPts;
  int deleteNormals = 0;
  vtkFloatArray* newNormals;
  vtkIdType i;
  double range[2], maxSpeed = 0;
  vtkCellArray* newStrips;
  vtkIdType npts = 0;
  const vtkIdType* ptsOrig = nullptr;
  vtkIdType offset = 0;
  vtkFloatArray* newTCoords = nullptr;
  int abort = 0;
  vtkIdType inCellId;
  double oldRadius = 1.0;

  // Check input and initialize
  //
  vtkDebugMacro(<< "Creating tube");

  if (!(inPts = input->GetPoints()) || (numPts = inPts->GetNumberOfPoints()) < 1 ||
    !(inLines = input->GetLines()) || (numLines = inLines->GetNumberOfCells()) < 1)
  {
    return 1;
  }

  // Create the geometry and topology
  numNewPts = numPts * this->NumberOfSides;
  newPts = vtkPoints::New();

  // Set the desired precision for the points in the output.
  if (this->OutputPointsPrecision == vtkAlgorithm::DEFAULT_PRECISION)
  {
    newPts->SetDataType(inPts->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(numNewPts);
  newNormals = vtkFloatArray::New();
  newNormals->SetName("TubeNormals");
  newNormals->SetNumberOfComponents(3);
  newNormals->Allocate(3 * numNewPts);
  newStrips = vtkCellArray::New();
  newStrips->AllocateEstimate(1, numNewPts);
  vtkCellArray* singlePolyline = vtkCellArray::New();

  // Point data: copy scalars, vectors, tcoords. Normals may be computed here.
  outPD->CopyNormalsOff();
  if ((this->GenerateTCoords == VTK_TCOORDS_FROM_SCALARS && inScalars) ||
    this->GenerateTCoords == VTK_TCOORDS_FROM_LENGTH ||
    this->GenerateTCoords == VTK_TCOORDS_FROM_NORMALIZED_LENGTH)
  {
    newTCoords = vtkFloatArray::New();
    newTCoords->SetNumberOfComponents(2);
    newTCoords->Allocate(numNewPts);
    outPD->CopyTCoordsOff();
  }
  outPD->CopyAllocate(pd, numNewPts);

  int generateNormals = 0;
  if (!(inNormals = pd->GetNormals()) || this->UseDefaultNormal)
  {
    deleteNormals = 1;
    inNormals = vtkFloatArray::New();
    inNormals->SetNumberOfComponents(3);
    inNormals->SetNumberOfTuples(numPts);

    if (this->UseDefaultNormal)
    {
      for (i = 0; i < numPts; i++)
      {
        inNormals->SetTuple(i, this->DefaultNormal);
      }
    }
    else
    {
      // Normal generation has been moved to lower in the function.
      // This allows each different polylines to share vertices, but have
      // their normals (and hence their tubes) calculated independently
      generateNormals = 1;
    }
  }

  // If varying width, get appropriate info.
  //
  if (inScalars)
  {
    inScalars->GetRange(range, 0);
    if ((range[1] - range[0]) == 0.0)
    {
      if (this->VaryRadius == VTK_VARY_RADIUS_BY_SCALAR)
      {
        vtkWarningMacro(<< "Scalar range is zero!");
      }
      range[1] = range[0] + 1.0;
    }
    if (this->VaryRadius == VTK_VARY_RADIUS_BY_ABSOLUTE_SCALAR)
    {
      // temporarily set the radius to 1.0 so that radius*scalar = scalar
      oldRadius = this->Radius;
      this->Radius = 1.0;
      if (range[0] < 0.0)
      {
        vtkWarningMacro(<< "Scalar values fall below zero when using absolute radius values!");
      }
    }
  }
  if (inVectors)
  {
    maxSpeed = inVectors->GetMaxNorm();
  }

  // Copy selected parts of cell data; certainly don't want normals
  //
  numNewCells = inLines->GetNumberOfCells() * this->NumberOfSides + 2;
  outCD->CopyNormalsOff();
  outCD->CopyAllocate(cd, numNewCells);

  //  Create points along each polyline that are connected into NumberOfSides
  //  triangle strips. Texture coordinates are optionally generated.
  //
  this->Theta = 2.0 * vtkMath::Pi() / this->NumberOfSides;
  vtkPolyLine* lineNormalGenerator = vtkPolyLine::New();
  // the line cellIds start after the last vert cellId
  inCellId = input->GetNumberOfVerts();
  for (inLines->InitTraversal(); inLines->GetNextCell(npts, ptsOrig) && !abort; inCellId++)
  {
    this->UpdateProgress((double)inCellId / numLines);
    abort = this->GetAbortExecute();

    // Make a copy of point indices to avoid modfiying input polydata cells
    // while removing degenerate lines.
    if (npts < 2)
    {
      continue; // skip tubing this polyline
    }
    std::vector<vtkIdType> ptsCopy(ptsOrig, ptsOrig + npts);
    vtkIdType* pts = ptsCopy.data();

    // remove degenerate lines to avoid warnings
    npts = static_cast<vtkIdType>(std::unique(pts, pts + npts, IdPointsEqual(inPts)) - pts);
    if (npts < 2)
    {
      continue; // skip tubing this polyline
    }

    // If necessary calculate normals, each polyline calculates its
    // normals independently, avoiding conflicts at shared vertices.
    if (generateNormals)
    {
      singlePolyline->Reset(); // avoid instantiation
      singlePolyline->InsertNextCell(npts, pts);
      lineNormalGenerator->GenerateSlidingNormals(inPts, singlePolyline, inNormals);
    }

    // Generate the points around the polyline. The tube is not stripped
    // if the polyline is bad.
    //
    if (!this->GeneratePoints(offset, npts, pts, inPts, newPts, pd, outPD, newNormals, inScalars,
          range, inVectors, maxSpeed, inNormals))
    {
      vtkWarningMacro(<< "Could not generate points!");
      continue; // skip tubing this polyline
    }

    // Generate the strips for this polyline (including caps)
    //
    this->GenerateStrips(offset, npts, pts, inCellId, cd, outCD, newStrips);

    // Generate the texture coordinates for this polyline
    //
    if (newTCoords)
    {
      this->GenerateTextureCoords(offset, npts, pts, inPts, inScalars, newTCoords);
    }

    // Compute the new offset for the next polyline
    offset = this->ComputeOffset(offset, npts);

  } // for all polylines

  singlePolyline->Delete();

  // reset the radius to ite original value if necessary
  if (this->VaryRadius == VTK_VARY_RADIUS_BY_ABSOLUTE_SCALAR)
  {
    this->Radius = oldRadius;
  }

  // Update ourselves
  //
  if (deleteNormals)
  {
    inNormals->Delete();
  }

  if (newTCoords)
  {
    outPD->SetTCoords(newTCoords);
    newTCoords->Delete();
  }

  output->SetPoints(newPts);
  newPts->Delete();

  output->SetStrips(newStrips);
  newStrips->Delete();

  outPD->SetNormals(newNormals);
  newNormals->Delete();
  lineNormalGenerator->Delete();

  output->Squeeze();

  return 1;
}

int vtkTubeFilter::GeneratePoints(vtkIdType offset, vtkIdType npts, const vtkIdType* pts,
  vtkPoints* inPts, vtkPoints* newPts, vtkPointData* pd, vtkPointData* outPD,
  vtkFloatArray* newNormals, vtkDataArray* inScalars, double range[2], vtkDataArray* inVectors,
  double maxSpeed, vtkDataArray* inNormals)
{
  vtkIdType j;
  int i, k;
  double p[3];
  double pNext[3];
  double sNext[3] = { 0.0, 0.0, 0.0 };
  double sPrev[3];
  double startCapNorm[3], endCapNorm[3];
  double n[3];
  double s[3];
  // double bevelAngle;
  double w[3];
  double nP[3];
  double sFactor = 1.0;
  double normal[3];
  vtkIdType ptId = offset;

  // Use "averaged" segment to create beveled effect.
  // Watch out for first and last points.
  //
  for (j = 0; j < npts; j++)
  {
    if (j == 0) // first point
    {
      inPts->GetPoint(pts[0], p);
      inPts->GetPoint(pts[1], pNext);
      for (i = 0; i < 3; i++)
      {
        sNext[i] = pNext[i] - p[i];
        sPrev[i] = sNext[i];
        startCapNorm[i] = -sPrev[i];
      }
      vtkMath::Normalize(startCapNorm);
    }
    else if (j == (npts - 1)) // last point
    {
      for (i = 0; i < 3; i++)
      {
        sPrev[i] = sNext[i];
        p[i] = pNext[i];
        endCapNorm[i] = sNext[i];
      }
      vtkMath::Normalize(endCapNorm);
    }
    else
    {
      for (i = 0; i < 3; i++)
      {
        p[i] = pNext[i];
      }
      inPts->GetPoint(pts[j + 1], pNext);
      for (i = 0; i < 3; i++)
      {
        sPrev[i] = sNext[i];
        sNext[i] = pNext[i] - p[i];
      }
    }

    inNormals->GetTuple(pts[j], n);

    if (vtkMath::Normalize(sNext) == 0.0)
    {
      vtkWarningMacro(<< "Coincident points!");
      return 0;
    }

    for (i = 0; i < 3; i++)
    {
      s[i] = (sPrev[i] + sNext[i]) / 2.0; // average vector
    }
    // if s is zero then just use sPrev cross n
    if (vtkMath::Normalize(s) == 0.0)
    {
      vtkDebugMacro(<< "Using alternate bevel vector");
      vtkMath::Cross(sPrev, n, s);
      if (vtkMath::Normalize(s) == 0.0)
      {
        vtkDebugMacro(<< "Using alternate bevel vector");
      }
    }

    /*    if ( (bevelAngle = vtkMath::Dot(sNext,sPrev)) > 1.0 )
          {
          bevelAngle = 1.0;
          }
        if ( bevelAngle < -1.0 )
          {
          bevelAngle = -1.0;
          }
        bevelAngle = acos((double)bevelAngle) / 2.0; //(0->90 degrees)
        if ( (bevelAngle = cos(bevelAngle)) == 0.0 )
          {
          bevelAngle = 1.0;
          }

        bevelAngle = this->Radius / bevelAngle; //keep tube constant radius
    */
    vtkMath::Cross(s, n, w);
    if (vtkMath::Normalize(w) == 0.0)
    {
      vtkWarningMacro(<< "Bad normal s = " << s[0] << " " << s[1] << " " << s[2] << " n = " << n[0]
                      << " " << n[1] << " " << n[2]);
      return 0;
    }

    vtkMath::Cross(w, s, nP); // create orthogonal coordinate system
    vtkMath::Normalize(nP);

    // Compute a scale factor based on scalars or vectors
    if (inScalars && this->VaryRadius == VTK_VARY_RADIUS_BY_SCALAR)
    {
      sFactor = 1.0 +
        ((this->RadiusFactor - 1.0) * (inScalars->GetComponent(pts[j], 0) - range[0]) /
          (range[1] - range[0]));
    }
    else if (inVectors && this->VaryRadius == VTK_VARY_RADIUS_BY_VECTOR)
    {
      sFactor = sqrt((double)maxSpeed / vtkMath::Norm(inVectors->GetTuple(pts[j])));
      if (sFactor > this->RadiusFactor)
      {
        sFactor = this->RadiusFactor;
      }
    }
    else if (inVectors && this->VaryRadius == VTK_VARY_RADIUS_BY_VECTOR_NORM)
    {
      sFactor =
        1.0 + (this->RadiusFactor - 1.0) * vtkMath::Norm(inVectors->GetTuple(pts[j])) / maxSpeed;
    }
    else if (inScalars && this->VaryRadius == VTK_VARY_RADIUS_BY_ABSOLUTE_SCALAR)
    {
      sFactor = inScalars->GetComponent(pts[j], 0);
      if (sFactor < 0.0)
      {
        vtkWarningMacro(<< "Scalar value less than zero, skipping line");
        return 0;
      }
    }

    // create points around line
    if (this->SidesShareVertices)
    {
      for (k = 0; k < this->NumberOfSides; k++)
      {
        for (i = 0; i < 3; i++)
        {
          normal[i] = w[i] * cos((double)k * this->Theta) + nP[i] * sin((double)k * this->Theta);
          s[i] = p[i] + this->Radius * sFactor * normal[i];
        }
        newPts->InsertPoint(ptId, s);
        newNormals->InsertTuple(ptId, normal);
        outPD->CopyData(pd, pts[j], ptId);
        ptId++;
      } // for each side
    }
    else
    {
      double n_left[3], n_right[3];
      for (k = 0; k < this->NumberOfSides; k++)
      {
        for (i = 0; i < 3; i++)
        {
          // Create duplicate vertices at each point
          // and adjust the associated normals so that they are
          // oriented with the facets. This preserves the tube's
          // polygonal appearance, as if by flat-shading around the tube,
          // while still allowing smooth (gouraud) shading along the
          // tube as it bends.
          normal[i] = w[i] * cos((double)(k + 0.0) * this->Theta) +
            nP[i] * sin((double)(k + 0.0) * this->Theta);
          n_right[i] = w[i] * cos((double)(k - 0.5) * this->Theta) +
            nP[i] * sin((double)(k - 0.5) * this->Theta);
          n_left[i] = w[i] * cos((double)(k + 0.5) * this->Theta) +
            nP[i] * sin((double)(k + 0.5) * this->Theta);
          s[i] = p[i] + this->Radius * sFactor * normal[i];
        }
        newPts->InsertPoint(ptId, s);
        newNormals->InsertTuple(ptId, n_right);
        outPD->CopyData(pd, pts[j], ptId);
        newPts->InsertPoint(ptId + 1, s);
        newNormals->InsertTuple(ptId + 1, n_left);
        outPD->CopyData(pd, pts[j], ptId + 1);
        ptId += 2;
      } // for each side
    }   // else separate vertices
  }     // for all points in polyline

  // Produce end points for cap. They are placed at tail end of points.
  if (this->Capping)
  {
    int numCapSides = this->NumberOfSides;
    int capIncr = 1;
    if (!this->SidesShareVertices)
    {
      numCapSides = 2 * this->NumberOfSides;
      capIncr = 2;
    }

    // the start cap
    for (k = 0; k < numCapSides; k += capIncr)
    {
      newPts->GetPoint(offset + k, s);
      newPts->InsertPoint(ptId, s);
      newNormals->InsertTuple(ptId, startCapNorm);
      outPD->CopyData(pd, pts[0], ptId);
      ptId++;
    }
    // the end cap
    int endOffset = offset + (npts - 1) * this->NumberOfSides;
    if (!this->SidesShareVertices)
    {
      endOffset = offset + 2 * (npts - 1) * this->NumberOfSides;
    }
    for (k = 0; k < numCapSides; k += capIncr)
    {
      newPts->GetPoint(endOffset + k, s);
      newPts->InsertPoint(ptId, s);
      newNormals->InsertTuple(ptId, endCapNorm);
      outPD->CopyData(pd, pts[npts - 1], ptId);
      ptId++;
    }
  } // if capping

  return 1;
}

void vtkTubeFilter::GenerateStrips(vtkIdType offset, vtkIdType npts,
  const vtkIdType* vtkNotUsed(pts), vtkIdType inCellId, vtkCellData* cd, vtkCellData* outCD,
  vtkCellArray* newStrips)
{
  vtkIdType i, outCellId;
  int k;
  int i1, i2, i3;

  if (this->SidesShareVertices)
  {
    for (k = this->Offset; k < (this->NumberOfSides + this->Offset); k += this->OnRatio)
    {
      i1 = k % this->NumberOfSides;
      i2 = (k + 1) % this->NumberOfSides;
      outCellId = newStrips->InsertNextCell(npts * 2);
      outCD->CopyData(cd, inCellId, outCellId);
      for (i = 0; i < npts; i++)
      {
        i3 = i * this->NumberOfSides;
        newStrips->InsertCellPoint(offset + i2 + i3);
        newStrips->InsertCellPoint(offset + i1 + i3);
      }
    } // for each side of the tube
  }
  else
  {
    for (k = this->Offset; k < (this->NumberOfSides + this->Offset); k += this->OnRatio)
    {
      i1 = 2 * (k % this->NumberOfSides) + 1;
      i2 = 2 * ((k + 1) % this->NumberOfSides);
      outCellId = newStrips->InsertNextCell(npts * 2);
      outCD->CopyData(cd, inCellId, outCellId);
      for (i = 0; i < npts; i++)
      {
        i3 = i * 2 * this->NumberOfSides;
        newStrips->InsertCellPoint(offset + i2 + i3);
        newStrips->InsertCellPoint(offset + i1 + i3);
      }
    } // for each side of the tube
  }

  // Take care of capping. The caps are n-sided polygons that can be
  // easily triangle stripped.
  if (this->Capping)
  {
    vtkIdType startIdx = offset + npts * this->NumberOfSides;
    vtkIdType idx;

    if (!this->SidesShareVertices)
    {
      startIdx = offset + 2 * npts * this->NumberOfSides;
    }

    // The start cap
    outCellId = newStrips->InsertNextCell(this->NumberOfSides);
    outCD->CopyData(cd, inCellId, outCellId);
    newStrips->InsertCellPoint(startIdx);
    newStrips->InsertCellPoint(startIdx + 1);
    for (i1 = this->NumberOfSides - 1, i2 = 2, k = 0; k < (this->NumberOfSides - 2); k++)
    {
      if ((k % 2))
      {
        idx = startIdx + i2;
        newStrips->InsertCellPoint(idx);
        i2++;
      }
      else
      {
        idx = startIdx + i1;
        newStrips->InsertCellPoint(idx);
        i1--;
      }
    }

    // The end cap - reversed order to be consistent with normal
    startIdx += this->NumberOfSides;
    outCellId = newStrips->InsertNextCell(this->NumberOfSides);
    outCD->CopyData(cd, inCellId, outCellId);
    newStrips->InsertCellPoint(startIdx);
    newStrips->InsertCellPoint(startIdx + this->NumberOfSides - 1);
    for (i1 = this->NumberOfSides - 2, i2 = 1, k = 0; k < (this->NumberOfSides - 2); k++)
    {
      if ((k % 2))
      {
        idx = startIdx + i1;
        newStrips->InsertCellPoint(idx);
        i1--;
      }
      else
      {
        idx = startIdx + i2;
        newStrips->InsertCellPoint(idx);
        i2++;
      }
    }
  }
}

void vtkTubeFilter::GenerateTextureCoords(vtkIdType offset, vtkIdType npts, const vtkIdType* pts,
  vtkPoints* inPts, vtkDataArray* inScalars, vtkFloatArray* newTCoords)
{
  vtkIdType i;
  int k;
  double tc = 0.0;

  int numSides = this->NumberOfSides;
  if (!this->SidesShareVertices)
  {
    numSides = 2 * this->NumberOfSides;
  }

  double s0, s;
  if (this->GenerateTCoords == VTK_TCOORDS_FROM_SCALARS)
  {
    s0 = inScalars->GetTuple1(pts[0]);
    for (i = 0; i < npts; i++)
    {
      s = inScalars->GetTuple1(pts[i]);
      tc = (s - s0) / this->TextureLength;
      for (k = 0; k < numSides; k++)
      {
        double tcy = static_cast<double>(k) / (numSides - 1);
        newTCoords->InsertTuple2(offset + i * numSides + k, tc, tcy);
      }
    }
  }
  else if (this->GenerateTCoords == VTK_TCOORDS_FROM_LENGTH)
  {
    double xPrev[3], x[3], len = 0.0;
    inPts->GetPoint(pts[0], xPrev);
    for (i = 0; i < npts; i++)
    {
      inPts->GetPoint(pts[i], x);
      len += sqrt(vtkMath::Distance2BetweenPoints(x, xPrev));
      tc = len / this->TextureLength;
      for (k = 0; k < numSides; k++)
      {
        double tcy = static_cast<double>(k) / (numSides - 1);
        newTCoords->InsertTuple2(offset + i * numSides + k, tc, tcy);
      }

      xPrev[0] = x[0];
      xPrev[1] = x[1];
      xPrev[2] = x[2];
    }
  }
  else if (this->GenerateTCoords == VTK_TCOORDS_FROM_NORMALIZED_LENGTH)
  {
    double xPrev[3], x[3], length = 0.0, len = 0.0;
    inPts->GetPoint(pts[0], xPrev);
    for (i = 0; i < npts; i++)
    {
      inPts->GetPoint(pts[i], x);
      length += sqrt(vtkMath::Distance2BetweenPoints(x, xPrev));
      xPrev[0] = x[0];
      xPrev[1] = x[1];
      xPrev[2] = x[2];
    }

    inPts->GetPoint(pts[0], xPrev);
    for (i = 0; i < npts; i++)
    {
      inPts->GetPoint(pts[i], x);
      len += sqrt(vtkMath::Distance2BetweenPoints(x, xPrev));
      tc = len / length;
      for (k = 0; k < numSides; k++)
      {
        double tcy = static_cast<double>(k) / (numSides - 1);
        newTCoords->InsertTuple2(offset + i * numSides + k, tc, tcy);
      }
      xPrev[0] = x[0];
      xPrev[1] = x[1];
      xPrev[2] = x[2];
    }
  }

  // Capping, set the endpoints as appropriate
  if (this->Capping)
  {
    int ik;
    vtkIdType startIdx = offset + npts * numSides;

    // start cap
    for (ik = 0; ik < this->NumberOfSides; ik++)
    {
      newTCoords->InsertTuple2(startIdx + ik, 0.0, 0.0);
    }

    // end cap
    for (ik = 0; ik < this->NumberOfSides; ik++)
    {
      newTCoords->InsertTuple2(startIdx + this->NumberOfSides + ik, tc, 0.0);
    }
  }
}

// Compute the number of points in this tube
vtkIdType vtkTubeFilter::ComputeOffset(vtkIdType offset, vtkIdType npts)
{
  if (this->SidesShareVertices)
  {
    offset += this->NumberOfSides * npts;
  }
  else
  {
    offset += 2 * this->NumberOfSides * npts; // points are duplicated
  }

  if (this->Capping)
  {
    offset += 2 * this->NumberOfSides; // cap points are duplicated
  }

  return offset;
}

// Description:
// Return the method of varying tube radius descriptive character string.
const char* vtkTubeFilter::GetVaryRadiusAsString()
{
  if (this->VaryRadius == VTK_VARY_RADIUS_OFF)
  {
    return "VaryRadiusOff";
  }
  else if (this->VaryRadius == VTK_VARY_RADIUS_BY_SCALAR)
  {
    return "VaryRadiusByScalar";
  }
  else if (this->VaryRadius == VTK_VARY_RADIUS_BY_ABSOLUTE_SCALAR)
  {
    return "VaryRadiusByAbsoluteScalar";
  }
  else if (this->VaryRadius == VTK_VARY_RADIUS_BY_VECTOR)
  {
    return "VaryRadiusByVector";
  }
  else
  {
    return "VaryRadiusByVectorNorm";
  }
}

// Description:
// Return the method of generating the texture coordinates.
const char* vtkTubeFilter::GetGenerateTCoordsAsString()
{
  if (this->GenerateTCoords == VTK_TCOORDS_OFF)
  {
    return "GenerateTCoordsOff";
  }
  else if (this->GenerateTCoords == VTK_TCOORDS_FROM_SCALARS)
  {
    return "GenerateTCoordsFromScalar";
  }
  else if (this->GenerateTCoords == VTK_TCOORDS_FROM_LENGTH)
  {
    return "GenerateTCoordsFromLength";
  }
  else
  {
    return "GenerateTCoordsFromNormalizedLength";
  }
}

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

  os << indent << "Radius: " << this->Radius << "\n";
  os << indent << "Vary Radius: " << this->GetVaryRadiusAsString() << endl;
  os << indent << "Radius Factor: " << this->RadiusFactor << "\n";
  os << indent << "Number Of Sides: " << this->NumberOfSides << "\n";
  os << indent << "On Ratio: " << this->OnRatio << "\n";
  os << indent << "Offset: " << this->Offset << "\n";

  os << indent << "Use Default Normal: " << (this->UseDefaultNormal ? "On\n" : "Off\n");
  os << indent << "Sides Share Vertices: " << (this->SidesShareVertices ? "On\n" : "Off\n");
  os << indent << "Default Normal: "
     << "( " << this->DefaultNormal[0] << ", " << this->DefaultNormal[1] << ", "
     << this->DefaultNormal[2] << " )\n";
  os << indent << "Capping: " << (this->Capping ? "On\n" : "Off\n");
  os << indent << "Generate TCoords: " << this->GetGenerateTCoordsAsString() << endl;
  os << indent << "Texture Length: " << this->TextureLength << endl;
  os << indent << "Output Points Precision: " << this->OutputPointsPrecision << endl;
}
