VTK-5.0.0/Graphics/vtkRectilinearGridToTetrahedra.cxx

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

  Program:   Visualization Toolkit
  Module:    $RCSfile: vtkRectilinearGridToTetrahedra.cxx,v $

  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 "vtkRectilinearGridToTetrahedra.h"

#include "vtkCellArray.h"
#include "vtkCellData.h"
#include "vtkSignedCharArray.h"
#include "vtkExecutive.h"
#include "vtkFloatArray.h"
#include "vtkIdList.h"
#include "vtkInformation.h"
#include "vtkInformationVector.h"
#include "vtkIntArray.h"
#include "vtkObjectFactory.h"
#include "vtkRectilinearGrid.h"
#include "vtkUnstructuredGrid.h"
#include "vtkVoxel.h"

vtkCxxRevisionMacro(vtkRectilinearGridToTetrahedra, "$Revision: 1.14 $");
vtkStandardNewMacro(vtkRectilinearGridToTetrahedra);

// ways to convert to a voxel to tetrahedra.
// Note that the values 0 and 1 and -1 and 2 are important in
// DetermineGridDivisionTypes()
#define VTK_TETRAHEDRALIZE_5                 0
#define VTK_TETRAHEDRALIZE_5_FLIP            1
#define VTK_TETRAHEDRALIZE_6                 6
#define VTK_TETRAHEDRALIZE_12_CONFORM        -1
#define VTK_TETRAHEDRALIZE_12_CONFORM_FLIP   2
#define VTK_TETRAHEDRALIZE_12                10

//-------------------------------------------------------------------------

vtkRectilinearGridToTetrahedra::vtkRectilinearGridToTetrahedra()
{
  this->TetraPerCell  = VTK_VOXEL_TO_5_TET;
  this->RememberVoxelId = 0;
}

//----------------------------------------------------------------------------

void vtkRectilinearGridToTetrahedra::SetInput(const double ExtentX, 
                                              const double ExtentY,
                                              const double ExtentZ, 
                                              const double SpacingX,
                                              const double SpacingY,
                                              const double SpacingZ,
                                              const double tol)
{
  double Extent[3];
  double Spacing[3];
  Extent[0]  = ExtentX;    Extent[1] = ExtentY;    Extent[2] = ExtentZ;
  Spacing[0] = SpacingX;  Spacing[1] = SpacingY;  Spacing[2] = SpacingZ;
  this->SetInput(Extent,Spacing,tol);
}


//----------------------------------------------------------------------------

// Create an input for the filter
void vtkRectilinearGridToTetrahedra::SetInput(const double Extent[3], 
                                              const double Spacing[3], 
                                              const double tol)
{
  //
  // Determine the number of points in each direction, and the positions
  // The last voxel may have a different spacing to fit inside
  // the selected region
  // 

  int i, j;
  int NumPointsInDir[3];
  vtkFloatArray *Coord[3];
  for(i = 0;i<3;i++)
    {
    double NumRegion = Extent[i]/Spacing[i];

    // If we are really close to an integer number of elements, use the 
    // integer number
    if (fabs(NumRegion - floor(NumRegion+0.5)) < tol*Spacing[i])
      NumPointsInDir[i] = ((int) floor(NumRegion+0.5)) + 1;
    else 
      NumPointsInDir[i] = (int) ceil(Extent[i]/Spacing[i])+1;
    Coord[i] = vtkFloatArray::New();
    Coord[i]->SetNumberOfValues(NumPointsInDir[i]+1);

     // The last data point inserted is exactly the Extent
    // Thus avoiding a bit of numerical error.
    for(j=0;j<NumPointsInDir[i]-1;j++)
      {
      Coord[i]->SetValue(j,Spacing[i]*j);
      }
    Coord[i]->SetValue(NumPointsInDir[i]-1,Extent[i]);
    }

  //
  // Form the grid
  //

  vtkRectilinearGrid *RectGrid = vtkRectilinearGrid::New();
  RectGrid->SetDimensions(NumPointsInDir);
  RectGrid->SetXCoordinates(Coord[0]);
  RectGrid->SetYCoordinates(Coord[1]);
  RectGrid->SetZCoordinates(Coord[2]);

  Coord[0]->Delete();
  Coord[1]->Delete();
  Coord[2]->Delete();

  // Get the reference counting right.
  this->Superclass::SetInput(RectGrid);
  RectGrid->Delete();
}

//----------------------------------------------------------------------------

// Determine how to Divide each voxel in the vtkRectilinearGrid
void vtkRectilinearGridToTetrahedra::DetermineGridDivisionTypes(
                                             vtkRectilinearGrid *RectGrid,
                                             vtkSignedCharArray *VoxelSubdivisionType,
                                             const int &TetraPerCell)
{
  int numRec = RectGrid->GetNumberOfCells();
  int NumPointsInDir[3];
  RectGrid->GetDimensions(NumPointsInDir);

  // How to break into Tetrahedra.
  // For division into 5's, we need to flip from one orientation to
  // the next

  int Rec[3];
  int flip;
  int i;

  switch (TetraPerCell)
    {
    case (VTK_VOXEL_TO_12_TET):
      for(i=0;i<numRec;i++)
        {
        VoxelSubdivisionType->SetValue(i,VTK_TETRAHEDRALIZE_12);
        }
    break;
    case (VTK_VOXEL_TO_6_TET):
      for(i=0;i<numRec;i++)
        {
        VoxelSubdivisionType->SetValue(i,VTK_TETRAHEDRALIZE_6);
        }
    break;
    case (VTK_VOXEL_TO_5_TET):
      for(Rec[0] = 0; Rec[0]<NumPointsInDir[0]-1; Rec[0]++)
        {
        for(Rec[1] = 0; Rec[1]<NumPointsInDir[1]-1; Rec[1]++)
          {
          flip = ( Rec[1] + Rec[0] ) % 2;
          for(Rec[2] = 0; Rec[2]<NumPointsInDir[2]-1; Rec[2]++)
            {
            VoxelSubdivisionType->SetValue(RectGrid->ComputeCellId(Rec),flip);
            flip = 1 - flip;
            }
          }
        }
    break;
    case (VTK_VOXEL_TO_5_AND_12_TET):
      for(Rec[0] = 0; Rec[0]<NumPointsInDir[0]-1; Rec[0]++)
        {
        for(Rec[1] = 0; Rec[1]<NumPointsInDir[1]-1; Rec[1]++)
          {
          flip = ( Rec[1] + Rec[0] ) % 2;
          for(Rec[2] = 0; Rec[2]<NumPointsInDir[2]-1; Rec[2]++)
            {
            int CellId = RectGrid->ComputeCellId(Rec);
            if (VoxelSubdivisionType->GetValue(CellId) == 12)
              VoxelSubdivisionType->SetValue(CellId,3*flip-1);
            else VoxelSubdivisionType->SetValue(CellId,flip);
            flip = 1 - flip;
            }
          }
        }
    break;
    }
}

//----------------------------------------------------------------------------

// Take the grid and make it into a tetrahedral mesh.
void vtkRectilinearGridToTetrahedra::GridToTetMesh(vtkRectilinearGrid *RectGrid,
                                vtkSignedCharArray *VoxelSubdivisionType,
                                const int &TetraPerCell,
                                const int &RememberVoxelId,
                                vtkUnstructuredGrid *TetMesh)
{
  int i, j;
  int numPts = RectGrid->GetNumberOfPoints();
  int numRec = RectGrid->GetNumberOfCells();

  // We need a point list and a cell list
  vtkPoints *NodePoints = vtkPoints::New();
  vtkCellArray *TetList = vtkCellArray::New();

  // Guess number of points and cells!! 
  // For mixture of 5 and 12 tet per cell, 
  // it is easier to way overguess to avoid re-allocation
  // slowness and range checking during insertion.

  switch (TetraPerCell)
    {
    case (VTK_VOXEL_TO_5_TET):
      NodePoints->Allocate(numPts);
      TetList->Allocate(numPts*5*5,numPts);
    break;
    case (VTK_VOXEL_TO_5_AND_12_TET):
    case (VTK_VOXEL_TO_12_TET):
      NodePoints->Allocate(numPts*2);
      TetList->Allocate(numPts*5*12,numPts);
    break;
    }

  // Start by copying over the points
  for(i=0;i<numPts;i++)
    {
    NodePoints->InsertNextPoint(RectGrid->GetPoint(i));
    }

  // If they want, we can add Scalar Data
  // to the Tets indicating the Voxel Id the tet
  // came from.
  vtkIntArray *TetOriginalVoxel = NULL;
  if (RememberVoxelId) {
    TetOriginalVoxel = vtkIntArray::New();
    TetOriginalVoxel->Allocate(12*numRec);
  }

  // 9 ids, 8 corners and a possible center to be added later
  //        during the tet creation
  vtkIdList *VoxelCorners = vtkIdList::New();
  VoxelCorners->SetNumberOfIds(9);

  int NumTetFromVoxel;
  for(i=0;i<numRec;i++)
    {
    RectGrid->GetCellPoints(i,VoxelCorners);
    NumTetFromVoxel = TetrahedralizeVoxel(VoxelCorners,
                                          (int)VoxelSubdivisionType->GetValue(i),
                                          NodePoints,TetList);
    if (RememberVoxelId)
      {
      for(j=0;j<NumTetFromVoxel;j++)
        {
        TetOriginalVoxel->InsertNextValue(i);
        }
      }
    }
  
  //
  // It may be there are extra points at the end of the PointList.
  //

  NodePoints->Squeeze();

  //
  // Form the Mesh
  //

  // Need to tell the tet mesh that every cell  is a Tetrahedron
  int numTet = TetList->GetNumberOfCells();
  int *CellTypes = new int[numTet];
  for(i=0;i<numTet;i++)
    {
    CellTypes[i] = VTK_TETRA;
    }

  TetMesh->SetPoints(NodePoints);
  TetMesh->SetCells(CellTypes,TetList);

  //
  // Add Scalar Types if wanted
  //

  if(RememberVoxelId)
    {
    TetOriginalVoxel->Squeeze();
    int idx = TetMesh->GetCellData()->AddArray(TetOriginalVoxel);
    TetMesh->GetCellData()->SetActiveAttribute(idx, vtkDataSetAttributes::SCALARS);
    TetOriginalVoxel->Delete();
    }

  //
  // Clean Up
  // 
  delete[] CellTypes;
  NodePoints->Delete();
  TetList->Delete();
  VoxelCorners->Delete();

  TetMesh->Squeeze();
}

//----------------------------------------------------------------------------
// Helper Function for Tetrahedralize Voxel
inline void vtkRectilinearGridToTetrahedra::TetrahedralizeAddCenterPoint(
                                                    vtkIdList *VoxelCorners,
                                                    vtkPoints *NodeList)
{
  // Need to add a center point
  double c1[3], c2[3];
  NodeList->GetPoint(VoxelCorners->GetId(0), c2);
  NodeList->GetPoint(VoxelCorners->GetId(7), c1);
  double center[3];
  center[0] = (c1[0] + c2[0])/2.0;
  center[1] = (c1[1] + c2[1])/2.0;
  center[2] = (c1[2] + c2[2])/2.0;
  
  VoxelCorners->InsertId(8,NodeList->InsertNextPoint(center));
}

//----------------------------------------------------------------------------

// Split A Cube into Tetrahedrons
// According to the DivisionType
// There had better be 0..8 voxel corners, though only 0..7 maybe needed.
// Why? This function may add id 8 to VoxelCorners.
// If a point needs to be inserted into the nodelist, itselt
// it at NextPointId. Assume there is space in the nodelist.
// Return the number of Tets Added.


int vtkRectilinearGridToTetrahedra::TetrahedralizeVoxel(vtkIdList *VoxelCorners,
                                     const int &DivisionType,
                                     vtkPoints *NodeList,
                                     vtkCellArray *TetList)
{

// See vtkVoxel::Triangulate
/*  Looking at the rect: Corner labeling 

     0  1
     2  3

   Directly behind them:
    4   5
    6   7

and 8 is in the middle of the cube if used

Want right handed Tetrahedra...
*/

  // Split voxel in 2 along diagonal, 3 tets on either side
 static int tet6[6][4] =
   { 
     {1,6,2,3}, {1,6,7,5}, {1,6,3,7},
     {1,6,0,2}, {1,6,5,4}, {1,6,4,0},
   };

 static int tet5[5][4]      = 
   { {0,1,4,2},{1,4,7,5},{1,4,2,7},{1,2,3,7},{2,7,4,6} };
 static int tet5flip[5][4]  = 
   { {3,1,0,5}, {0,3,6,2}, {3,5,6,7}, {0,6,5,4}, {0,3,5,6}};

  // 12 tet to confirm to tet5
  static int tet12_conform[12][4] = {
  /* Left side */
    {8,2,4,0},
    {8,4,2,6},
  /* Back side */
    {8,7,4,6},
    {8,4,7,5},
  /* Bottom side */
    {8,7,2,3},
    {8,2,7,6},
  /* Right side */
    {8,7,1,5},
    {8,1,7,3},
  /* Front side */
    {8,1,2,0},
    {8,2,1,3},
  /* Top side */
    {8,4,1,0}, 
    {8,1,4,5}};

  // 12 tet to confirm to tet5flip
  static int tet12_conform_flip[12][4] = {
  /* Left side */ 
    {8,0,6,4},
    {8,6,0,2},
  /* Back side */ 
    {8,5,6,7},
    {8,6,5,4},
  /* Bottom side */ 
    {8,3,6,2},
    {8,6,3,7},
  /* Right side */
    {8,3,5,7},
    {8,5,3,1},
  /* Front side */
    {8,3,0,1},
    {8,0,3,2},
  /* Top side */
    {8,5,0,4},
    {8,0,5,1}};

  // 12 tet chosen to have the least number of edges per node
  static int tet12[12][4] = {
  /* Left side */
    {8,2,4,0},
    {8,4,2,6},
  /* Back side */                                                     
    {8,7,4,6},
    {8,4,7,5},
  /* Right side */                                                    
    {8,3,5,7},
    {8,5,3,1},
  /* Front side */                                                   
    {8,3,0,1},
    {8,0,3,2},
  /* Top side */                                                     
    {8,5,0,4},
    {8,0,5,1},
  /* Bottom side */                                                  
    {8,7,2,3},
    {8,2,7,6}};


  int i, j;
  // Get the point Ids
  int numTet = 0; // =0 removes warning messages
  vtkIdType TetPts[4];

  switch (DivisionType)
    {
    case (VTK_TETRAHEDRALIZE_6) : 
      numTet = 6;
      for(i=0;i<numTet;i++)
        {
        for(j=0;j<4;j++)
          {
          TetPts[j] = VoxelCorners->GetId(tet6[i][j]);
          }
        TetList->InsertNextCell((vtkIdType)4,TetPts);
        }
    break; 
    case (VTK_TETRAHEDRALIZE_5) : 
      numTet = 5;
      for(i=0;i<numTet;i++)
        {
        for(j=0;j<4;j++)
          {
          TetPts[j] = VoxelCorners->GetId(tet5[i][j]);
          }
        TetList->InsertNextCell((vtkIdType)4,TetPts);
        }
    break; 
    case (VTK_TETRAHEDRALIZE_5_FLIP) : 
      numTet = 5;
      for(i=0;i<numTet;i++)
        {
          for(j=0;j<4;j++)
            {
            TetPts[j] = VoxelCorners->GetId(tet5flip[i][j]);
            }
          TetList->InsertNextCell((vtkIdType)4,TetPts);
        }
    break; 
    case (VTK_TETRAHEDRALIZE_12) :
      numTet = 12;
      TetrahedralizeAddCenterPoint(VoxelCorners,NodeList);
      for(i=0;i<numTet;i++)
        {
        for(j=0;j<4;j++)
          {
          TetPts[j] = VoxelCorners->GetId(tet12[i][j]);
          }
        TetList->InsertNextCell((vtkIdType)4,TetPts);
        }
    break;
    case (VTK_TETRAHEDRALIZE_12_CONFORM) :
      numTet = 12;
      TetrahedralizeAddCenterPoint(VoxelCorners,NodeList);
      for(i=0;i<numTet;i++)
        {
        for(j=0;j<4;j++)
          {
          TetPts[j] = VoxelCorners->GetId(tet12_conform[i][j]);
          }
        TetList->InsertNextCell((vtkIdType)4,TetPts);
        }
    break;
    case (VTK_TETRAHEDRALIZE_12_CONFORM_FLIP) :
      numTet = 12;
      TetrahedralizeAddCenterPoint(VoxelCorners,NodeList);
      for(i=0;i<numTet;i++)
        {
        for(j=0;j<4;j++)
          {
          TetPts[j] = VoxelCorners->GetId(tet12_conform_flip[i][j]);
          }
        TetList->InsertNextCell((vtkIdType)4,TetPts);
        }
    break;
    }
  return numTet;
}

//----------------------------------------------------------------------------

int vtkRectilinearGridToTetrahedra::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 ouptut
  vtkRectilinearGrid *RectGrid = vtkRectilinearGrid::SafeDownCast(
    inInfo->Get(vtkDataObject::DATA_OBJECT()));
  vtkUnstructuredGrid *output = vtkUnstructuredGrid::SafeDownCast(
    outInfo->Get(vtkDataObject::DATA_OBJECT()));

  // Create internal version of VoxelSubdivisionType
  // VoxelSubdivisionType indicates how to subdivide each cell
  vtkSignedCharArray *VoxelSubdivisionType;
  VoxelSubdivisionType = vtkSignedCharArray::New();

  // If we have a mixture of 5 and 12 Tet, we need to get the information from
  // the scalars of the Input. Note that we will modify the array internally
  // so we need to copy it.
  if (this->TetraPerCell == VTK_VOXEL_TO_5_AND_12_TET)
    {
    vtkDataArray *TempVoxelSubdivisionType = RectGrid->GetCellData()->GetScalars();
    if((TempVoxelSubdivisionType == NULL))
      {
      vtkErrorMacro(<< "Scalars to input Should be set!");
      return 1;
      }
    VoxelSubdivisionType->SetNumberOfValues(RectGrid->GetNumberOfCells());
    VoxelSubdivisionType->vtkSignedCharArray::DeepCopy(TempVoxelSubdivisionType);
    }
  else
    { // Otherwise, just create the GridDivisionTypes
    VoxelSubdivisionType->SetNumberOfValues(RectGrid->GetNumberOfCells());
    }

  vtkDebugMacro(<<"Number of points: " 
                << RectGrid->GetNumberOfPoints());
  vtkDebugMacro(<< "Number of voxels in input: " 
                << RectGrid->GetNumberOfCells());

  // Determine how each Cell should be subdivided
  DetermineGridDivisionTypes(RectGrid,VoxelSubdivisionType,
                             this->TetraPerCell);

  // Subdivide each cell to a tetrahedron, forming the TetMesh
  GridToTetMesh(RectGrid,VoxelSubdivisionType,this->TetraPerCell,
                this->RememberVoxelId,output);

  vtkDebugMacro(<< "Number of output points: " 
                << output->GetNumberOfPoints());
  vtkDebugMacro(<< "Number of output tetrahedra: " 
                << output->GetNumberOfCells());

  // Clean Up
  VoxelSubdivisionType->Delete();

  return 1;
}

//----------------------------------------------------------------------------
int
vtkRectilinearGridToTetrahedra
::FillInputPortInformation(int port, vtkInformation* info)
{
  if(!this->Superclass::FillInputPortInformation(port, info))
    {
    return 0;
    }
  info->Set(vtkAlgorithm::INPUT_REQUIRED_DATA_TYPE(), "vtkRectilinearGrid");
  return 1;
}

//----------------------------------------------------------------------------

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

  os << indent << "Mesh Type: " << this->TetraPerCell << "\n";
  os << indent << "RememberVoxel Id: " << this->RememberVoxelId << "\n";
}