VTK-5.0.0/Graphics/vtkPolyDataNormals.cxx

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

  Program:   Visualization Toolkit
  Module:    $RCSfile: vtkPolyDataNormals.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 "vtkPolyDataNormals.h"

#include "vtkCellArray.h"
#include "vtkCellData.h"
#include "vtkFloatArray.h"
#include "vtkMath.h"
#include "vtkInformation.h"
#include "vtkInformationVector.h"
#include "vtkObjectFactory.h"
#include "vtkPointData.h"
#include "vtkPolyData.h"
#include "vtkPolygon.h"
#include "vtkTriangleStrip.h"
#include "vtkPriorityQueue.h"

vtkCxxRevisionMacro(vtkPolyDataNormals, "$Revision: 1.66 $");
vtkStandardNewMacro(vtkPolyDataNormals);

// Construct with feature angle=30, splitting and consistency turned on, 
// flipNormals turned off, and non-manifold traversal turned on.
vtkPolyDataNormals::vtkPolyDataNormals()
{
  this->FeatureAngle = 30.0;
  this->Splitting = 1;
  this->Consistency = 1;
  this->FlipNormals = 0;
  this->ComputePointNormals = 1;
  this->ComputeCellNormals = 0;
  this->NonManifoldTraversal = 1;
  this->AutoOrientNormals = 0;
  // some internal data
  this->NumFlips = 0;
}

#define VTK_CELL_NOT_VISITED     0
#define VTK_CELL_VISITED         1

// Generate normals for polygon meshes
int vtkPolyDataNormals::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
  vtkPolyData *input = vtkPolyData::SafeDownCast(
    inInfo->Get(vtkDataObject::DATA_OBJECT()));
  vtkPolyData *output = vtkPolyData::SafeDownCast(
    outInfo->Get(vtkDataObject::DATA_OBJECT()));

  int j;
  vtkIdType npts = 0;
  vtkIdType i;
  vtkIdType *pts = 0;
  vtkIdType numNewPts;
  double polyNormal[3], vertNormal[3], length;
  double flipDirection=1.0;
  vtkIdType numPolys, numStrips;
  vtkIdType cellId;
  vtkIdType numPts;
  vtkPoints *inPts;
  vtkCellArray *inPolys, *inStrips, *polys;
  vtkPoints *newPts = NULL;
  vtkFloatArray *newNormals;
  vtkPointData *pd, *outPD;
  vtkCellData *outCD;
  double n[3];
  vtkCellArray *newPolys;
  vtkIdType ptId, oldId;

  vtkDebugMacro(<<"Generating surface normals");

  numPolys=input->GetNumberOfPolys();
  numStrips=input->GetNumberOfStrips();
  if ( (numPts=input->GetNumberOfPoints()) < 1 )
    {
    vtkErrorMacro(<<"No data to generate normals for!");
    return 1;
    }


  // If there is nothing to do, pass the data through
  if ( this->ComputePointNormals == 0 && this->ComputeCellNormals == 0 || 
       (numPolys < 1 && numStrips < 1) )
    { //don't do anything! pass data through
    output->CopyStructure(input);
    output->GetPointData()->PassData(input->GetPointData());
    output->GetCellData()->PassData(input->GetCellData());
    return 1;
    }
  output->GetCellData()->PassData(input->GetCellData());
  output->SetFieldData(input->GetFieldData());

  // Load data into cell structure.  We need two copies: one is a 
  // non-writable mesh used to perform topological queries.  The other 
  // is used to write into and modify the connectivity of the mesh.
  //
  inPts = input->GetPoints();
  inPolys = input->GetPolys();
  inStrips = input->GetStrips();
  
  this->OldMesh = vtkPolyData::New();
  this->OldMesh->SetPoints(inPts);
  if ( numStrips > 0 ) //have to decompose strips into triangles
    {
    if ( numPolys > 0 )
      {
      polys = vtkCellArray::New();
      polys->DeepCopy(inPolys);
      }
    else 
      {
      polys = vtkCellArray::New();
      polys->Allocate(polys->EstimateSize(numStrips,5));
      }
    for ( inStrips->InitTraversal(); inStrips->GetNextCell(npts,pts); )
      {
      vtkTriangleStrip::DecomposeStrip(npts, pts, polys);
      }
    this->OldMesh->SetPolys(polys);
    polys->Delete();
    numPolys = polys->GetNumberOfCells();//added some new triangles
    }
  else
    {
    this->OldMesh->SetPolys(inPolys);
    polys = inPolys;
    }
  this->OldMesh->BuildLinks();
  this->UpdateProgress(0.10);
  
  pd = input->GetPointData();
  outPD = output->GetPointData();
    
  outCD = output->GetCellData();
    
  this->NewMesh = vtkPolyData::New();
  this->NewMesh->SetPoints(inPts);
  // create a copy because we're modifying it
  newPolys = vtkCellArray::New();
  newPolys->DeepCopy(polys);
  this->NewMesh->SetPolys(newPolys);
  this->NewMesh->BuildCells(); //builds connectivity

  // The visited array keeps track of which polygons have been visited.
  //
  if ( this->Consistency || this->Splitting || this->AutoOrientNormals ) 
    {
    this->Visited = new int[numPolys];
    memset(this->Visited, VTK_CELL_NOT_VISITED, numPolys*sizeof(int));
    this->CellIds = vtkIdList::New();
    this->CellIds->Allocate(VTK_CELL_SIZE);
    }
  else
    {
    this->Visited = NULL;
    }

  //  Traverse all polygons insuring proper direction of ordering.  This
  //  works by propagating a wave from a seed polygon to the polygon's
  //  edge neighbors. Each neighbor may be reordered to maintain consistency
  //  with its (already checked) neighbors.
  //
  this->NumFlips = 0;
  if (this->AutoOrientNormals)
    {
    // No need to check this->Consistency. It's implied.

    // Ok, here's the basic idea: the "left-most" polygon should 
    // have its outward pointing normal facing left. If it doesn't,
    // reverse the vertex order. Then use it as the seed for other
    // connected polys. To find left-most polygon, first find left-most
    // point, and examine neighboring polys and see which one
    // has a normal that's "most aligned" with the X-axis. This process
    // will need to be repeated to handle all connected components in
    // the mesh. Report bugs/issues to cvolpe@ara.com.
    int foundLeftmostCell;
    vtkIdType leftmostCellID=-1, currentPointID, currentCellID;
    vtkIdType *leftmostCells;
    unsigned short nleftmostCells;
    vtkIdType *cellPts;
    vtkIdType nCellPts;
    int cIdx;
    double bestNormalAbsXComponent;
    int bestReverseFlag;
    vtkPriorityQueue *leftmostPoints = vtkPriorityQueue::New();
    this->Wave = vtkIdList::New();
    this->Wave->Allocate(numPolys/4+1,numPolys);
    this->Wave2 = vtkIdList::New();
    this->Wave2->Allocate(numPolys/4+1,numPolys);

    // Put all the points in the priority queue, based on x coord
    // So that we can find leftmost point
    leftmostPoints->Allocate(numPts);
    for (ptId=0; ptId < numPts; ptId++)
      {
      leftmostPoints->Insert(inPts->GetPoint(ptId)[0],ptId);
      }

    // Repeat this while loop as long as the queue is not empty,
    // because there may be multiple connected components, each of
    // which needs to be seeded independently with a correctly
    // oriented polygon.
    while (leftmostPoints->GetNumberOfItems())
      {
      foundLeftmostCell = 0;
      // Keep iterating through leftmost points and cells located at
      // those points until I've got a leftmost point with 
      // unvisited cells attached and I've found the best cell
      // at that point
      do {
        currentPointID = leftmostPoints->Pop();
        this->OldMesh->GetPointCells(currentPointID, nleftmostCells, leftmostCells);
        bestNormalAbsXComponent = 0.0;
        bestReverseFlag = 0;
        for (cIdx = 0; cIdx < nleftmostCells; cIdx++)
          {
          currentCellID = leftmostCells[cIdx];
          if (this->Visited[currentCellID] == VTK_CELL_VISITED)
            {
            continue;
            }
          this->OldMesh->GetCellPoints(currentCellID, nCellPts, cellPts);
          vtkPolygon::ComputeNormal(inPts, nCellPts, cellPts, n);
          // Ok, see if this leftmost cell candidate is the best
          // so far
          if (fabs(n[0]) > bestNormalAbsXComponent)
            {
            bestNormalAbsXComponent = fabs(n[0]);
            leftmostCellID = currentCellID;
            // If the current leftmost cell's normal is pointing to the
            // right, then the vertex ordering is wrong
            bestReverseFlag = (n[0] > 0);
            foundLeftmostCell = 1;
            } // if this normal is most x-aligned so far
          } // for each cell at current leftmost point
        } while (leftmostPoints->GetNumberOfItems() && !foundLeftmostCell);
      if (foundLeftmostCell)
        {
        // We've got the seed for a connected component! But do
        // we need to flip it first? We do, if it was pointed the wrong
        // way to begin with, or if the user requested flipping all
        // normals, but if both are true, then we leave it as it is.
        if (bestReverseFlag ^ this->FlipNormals)
          {
          this->NewMesh->ReverseCell(leftmostCellID);
          this->NumFlips++;
          }
        this->Wave->InsertNextId(leftmostCellID);
        this->Visited[leftmostCellID] = VTK_CELL_VISITED;
        this->TraverseAndOrder();
        this->Wave->Reset();
        this->Wave2->Reset();
        } // if found leftmost cell
      } // Still some points in the queue
    this->Wave->Delete();
    this->Wave2->Delete();
    vtkDebugMacro(<<"Reversed ordering of " << this->NumFlips << " polygons");
    } // automatically orient normals
  else
    {
    if ( this->Consistency ) 
      {    
      this->Wave = vtkIdList::New();
      this->Wave->Allocate(numPolys/4+1,numPolys);
      this->Wave2 = vtkIdList::New();
      this->Wave2->Allocate(numPolys/4+1,numPolys);
      for (cellId=0; cellId < numPolys; cellId++)
        {
        if ( this->Visited[cellId] == VTK_CELL_NOT_VISITED) 
          {
          if ( this->FlipNormals ) 
            {
            this->NumFlips++;
            this->NewMesh->ReverseCell(cellId);
            }
          this->Wave->InsertNextId(cellId);
          this->Visited[cellId] = VTK_CELL_VISITED; 
          this->TraverseAndOrder();
          }

        this->Wave->Reset();
        this->Wave2->Reset(); 
        }

      this->Wave->Delete();
      this->Wave2->Delete();
      vtkDebugMacro(<<"Reversed ordering of " << this->NumFlips << " polygons");
      }//Consistent ordering
    } // don't automatically orient normals
  
  this->UpdateProgress(0.333);

  //  Initial pass to compute polygon normals without effects of neighbors
  //
  this->PolyNormals = vtkFloatArray::New();
  this->PolyNormals->SetNumberOfComponents(3);
  this->PolyNormals->Allocate(3*numPolys);
  this->PolyNormals->SetName("Normals");
  this->PolyNormals->SetNumberOfTuples(numPolys);

  for (cellId=0, newPolys->InitTraversal(); newPolys->GetNextCell(npts,pts); 
       cellId++ )
    {
    if ((cellId % 1000) == 0)
      {
      this->UpdateProgress (0.333 + 0.333 * (double) cellId / (double) numPolys);
      if (this->GetAbortExecute())
        {
        break; 
        }
      }
    vtkPolygon::ComputeNormal(inPts, npts, pts, n);
    this->PolyNormals->SetTuple(cellId,n);
    }

  // Split mesh if sharp features
  if ( this->Splitting ) 
    {
    //  Traverse all nodes; evaluate loops and feature edges.  If feature
    //  edges found, split mesh creating new nodes.  Update polygon 
    // connectivity.
    //
    this->CosAngle = cos ((double) 
                          vtkMath::DegreesToRadians() * this->FeatureAngle);
    //  Splitting will create new points.  We have to create index array 
    // to map new points into old points.
    //
    this->Map = vtkIdList::New();
    this->Map->SetNumberOfIds(numPts);
    for (i=0; i < numPts; i++)
      {
      this->Map->SetId(i,i);
      }

    for (ptId=0; ptId < numPts; ptId++)
      {
      this->MarkAndSplit(ptId);
      }//for all input points

    numNewPts = this->Map->GetNumberOfIds();

    vtkDebugMacro(<<"Created " << numNewPts-numPts << " new points");

    //  Now need to map attributes of old points into new points.
    //
    outPD->CopyNormalsOff();
    outPD->CopyAllocate(pd,numNewPts);

    newPts = vtkPoints::New(); newPts->SetNumberOfPoints(numNewPts);
    for (ptId=0; ptId < numNewPts; ptId++)
      {
      oldId = this->Map->GetId(ptId);
      newPts->SetPoint(ptId,inPts->GetPoint(oldId));
      outPD->CopyData(pd,oldId,ptId);
      }
    this->Map->Delete();
    } //splitting

  else //no splitting, so no new points
    {
    numNewPts = numPts;
    outPD->CopyNormalsOff();
    outPD->PassData(pd);
    }

  if ( this->Consistency || this->Splitting )
    {
    delete [] this->Visited;
    this->CellIds->Delete();
    }

  this->UpdateProgress(0.80);

  //  Finally, traverse all elements, computing polygon normals and
  //  accumulating them at the vertices.
  //
  if ( this->FlipNormals && ! this->Consistency )
    {
    flipDirection = -1.0;
    }

  newNormals = vtkFloatArray::New();
  newNormals->SetNumberOfComponents(3);
  newNormals->SetNumberOfTuples(numNewPts);
  newNormals->SetName("Normals");
  n[0] = n[1] = n[2] = 0.0;
  for (i=0; i < numNewPts; i++)
    {
    newNormals->SetTuple(i,n);
    }

  if (this->ComputePointNormals)
    {
    for (cellId=0, newPolys->InitTraversal(); newPolys->GetNextCell(npts,pts); 
          cellId++ )
      {
      this->PolyNormals->GetTuple(cellId, polyNormal);

      for (i=0; i < npts; i++) 
        {
        newNormals->GetTuple(pts[i], vertNormal);
        for (j=0; j < 3; j++)
          {
          n[j] = vertNormal[j] + polyNormal[j];
          }
        newNormals->SetTuple(pts[i],n);
        }
      }

    for (i=0; i < numNewPts; i++) 
      {
      newNormals->GetTuple(i, vertNormal);
      length = vtkMath::Norm(vertNormal);
      if (length != 0.0) 
        {
        for (j=0; j < 3; j++)
          {
          n[j] = vertNormal[j] / length * flipDirection;
          }
        }
      newNormals->SetTuple(i,n);
      }
    }

  //  Update ourselves.  If no new nodes have been created (i.e., no
  //  splitting), we can simply pass data through.
  //
  if ( ! this->Splitting ) 
    {
    output->SetPoints(inPts);
    }

  //  If there is splitting, then have to send down the new data.
  //
  else
    {
    output->SetPoints(newPts);
    newPts->Delete();
    }

  if (this->ComputeCellNormals)
    {
    outCD->SetNormals(this->PolyNormals);
    }
  this->PolyNormals->Delete();

  if (this->ComputePointNormals)
    {
    outPD->SetNormals(newNormals);
    }
  newNormals->Delete();

  output->SetPolys(newPolys);
  newPolys->Delete();

  // copy the original vertices and lines to the output
  output->SetVerts(input->GetVerts());
  output->SetLines(input->GetLines());
                   
  this->OldMesh->Delete();
  this->NewMesh->Delete();

  return 1;
}

//  Propagate wave of consistently ordered polygons.
//
void vtkPolyDataNormals::TraverseAndOrder (void)
{
  vtkIdType p1, p2, i, k;
  int j, l;
  vtkIdType numIds, cellId;
  vtkIdType *pts, *neiPts, npts, numNeiPts;
  vtkIdType neighbor;
  vtkIdList *tmpWave;

  // propagate wave until nothing left in wave
  while ( (numIds=this->Wave->GetNumberOfIds()) > 0 )
    {
    for ( i=0; i < numIds; i++ )
      {
      cellId = this->Wave->GetId(i);

      this->NewMesh->GetCellPoints(cellId, npts, pts);

      for (j=0; j < npts; j++) //for each edge neighbor
        {
        p1 = pts[j];
        p2 = pts[(j+1)%npts];

        this->OldMesh->GetCellEdgeNeighbors(cellId, p1, p2, this->CellIds);

        //  Check the direction of the neighbor ordering.  Should be
        //  consistent with us (i.e., if we are n1->n2, 
        // neighbor should be n2->n1).
        if ( this->CellIds->GetNumberOfIds() == 1 ||
             this->NonManifoldTraversal )
          {
          for (k=0; k < this->CellIds->GetNumberOfIds(); k++) 
            {
            if (this->Visited[this->CellIds->GetId(k)]==VTK_CELL_NOT_VISITED) 
              {
              neighbor = this->CellIds->GetId(k);
              this->NewMesh->GetCellPoints(neighbor,numNeiPts,neiPts);
              for (l=0; l < numNeiPts; l++)
                {
                if (neiPts[l] == p2)
                  {
                  break;
                  }
                }

              //  Have to reverse ordering if neighbor not consistent
              //
              if ( neiPts[(l+1)%numNeiPts] != p1 ) 
                {
                this->NumFlips++;
                this->NewMesh->ReverseCell(neighbor);
                }
              this->Visited[neighbor] = VTK_CELL_VISITED; 
              this->Wave2->InsertNextId(neighbor);
              }// if cell not visited
            } // for each edge neighbor
          } //for manifold or non-manifold traversal allowed
        } // for all edges of this polygon
      } //for all cells in wave

    //swap wave and proceed with propagation
    tmpWave = this->Wave;
    this->Wave = this->Wave2;
    this->Wave2 = tmpWave;
    this->Wave2->Reset();
    } //while wave still propagating

  return;
}

//
//  Mark polygons around vertex.  Create new vertex (if necessary) and
//  replace (i.e., split mesh).
//
void vtkPolyDataNormals::MarkAndSplit (vtkIdType ptId)
{
  int i,j;

  // Get the cells using this point and make sure that we have to do something
  unsigned short ncells;
  vtkIdType *cells;
  this->OldMesh->GetPointCells(ptId,ncells,cells);
  if ( ncells <= 1 )
    {
    return; //point does not need to be further disconnected
    }

  // Start moving around the "cycle" of points using the point. Label
  // each point as requiring a visit. Then label each subregion of cells
  // connected to this point that are connected (and not separated by
  // a feature edge) with a given region number. For each N regions
  // created, N-1 duplicate (split) points are created. The split point
  // replaces the current point ptId in the polygons connectivity array.
  //
  // Start by initializing the cells as unvisited
  for (i=0; i<ncells; i++)
    {
    this->Visited[cells[i]] = -1;
    }

  // Loop over all cells and mark the region that each is in.
  //
  vtkIdType numPts;
  vtkIdType *pts;
  int numRegions = 0;
  vtkIdType spot, neiPt[2], nei, cellId, neiCellId;
  double thisNormal[3], neiNormal[3];
  for (j=0; j<ncells; j++) //for all cells connected to point
    {
    if ( this->Visited[cells[j]] < 0 ) //for all unvisited cells
      {
      this->Visited[cells[j]] = numRegions;
      //okay, mark all the cells connected to this seed cell and using ptId
      this->OldMesh->GetCellPoints(cells[j],numPts,pts);

      //find the two edges
      for (spot=0; spot < numPts; spot++)
        {
        if ( pts[spot] == ptId )
          {
          break;
          }
        }

      if ( spot == 0 ) 
        {
        neiPt[0] = pts[spot+1];
        neiPt[1] = pts[numPts-1];
        } 
      else if ( spot == (numPts-1) ) 
        {
        neiPt[0] = pts[spot-1];
        neiPt[1] = pts[0];
        } 
      else 
        {
        neiPt[0] = pts[spot+1];
        neiPt[1] = pts[spot-1];
        }

      for (i=0; i<2; i++) //for each of the two edges of the seed cell
        {
        cellId = cells[j];
        nei = neiPt[i];
        while ( cellId >= 0 ) //while we can grow this region
          {
          this->OldMesh->GetCellEdgeNeighbors(cellId,ptId,nei,this->CellIds);
          if ( this->CellIds->GetNumberOfIds() == 1 && 
               this->Visited[(neiCellId=this->CellIds->GetId(0))] < 0 )
            {
            this->PolyNormals->GetTuple(cellId, thisNormal);
            this->PolyNormals->GetTuple(neiCellId, neiNormal);

            if ( vtkMath::Dot(thisNormal,neiNormal) > CosAngle )
              {
              //visit and arrange to visit next edge neighbor
              this->Visited[neiCellId] = numRegions;
              cellId = neiCellId;
              this->OldMesh->GetCellPoints(cellId,numPts,pts);

              for (spot=0; spot < numPts; spot++)
                {
                if ( pts[spot] == ptId )
                  {
                  break;
                  }
                }

              if (spot == 0) 
                {
                nei = (pts[spot+1] != nei ? pts[spot+1] : pts[numPts-1]);
                } 
              else if (spot == (numPts-1)) 
                {
                nei = (pts[spot-1] != nei ? pts[spot-1] : pts[0]);
                } 
              else 
                {
                nei = (pts[spot+1] != nei ? pts[spot+1] : pts[spot-1]);
                }

              }//if not separated by edge angle
            else
              {
              cellId = -1; //separated by edge angle
              }
            }//if can move to edge neighbor
          else
            {
            cellId = -1;//separated by previous visit, boundary, or non-manifold
            }
          }//while visit wave is propagating
        }//for each of the two edges of the starting cell
      numRegions++;
      }//if cell is unvisited
    }//for all cells connected to point ptId
  
  if ( numRegions <=1 )
    {
    return; //a single region, no splitting ever required
    }

  // Okay, for all cells not in the first region, the ptId is
  // replaced with a new ptId, which is a duplicate of the first
  // point, but disconnected topologically.
  //
  vtkIdType lastId = this->Map->GetNumberOfIds();
  vtkIdType replacementPoint;
  for (j=0; j<ncells; j++)
    {
    if (this->Visited[cells[j]] > 0 ) //replace point if splitting needed
      {
      replacementPoint = lastId + this->Visited[cells[j]] - 1;
      
      this->Map->InsertId(replacementPoint, ptId);

      this->NewMesh->GetCellPoints(cells[j],numPts,pts);
      for (i=0; i < numPts; i++) 
        {
        if ( pts[i] == ptId ) 
          {
          pts[i] = replacementPoint; // this is very nasty! direct write!
          break;
          }
        }//replace ptId with split point
      }//if not in first regions and requiring splitting
    }//for all cells connected to ptId

  return;
}

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

  os << indent << "Feature Angle: " << this->FeatureAngle << "\n";
  os << indent << "Splitting: " << (this->Splitting ? "On\n" : "Off\n");
  os << indent << "Consistency: " << (this->Consistency ? "On\n" : "Off\n"); 
  os << indent << "Flip Normals: " << (this->FlipNormals ? "On\n" : "Off\n");
  os << indent << "Auto Orient Normals: " << (this->AutoOrientNormals ? "On\n" : "Off\n");
  os << indent << "Num Flips: " << this->NumFlips << endl;
  os << indent << "Compute Point Normals: " 
     << (this->ComputePointNormals ? "On\n" : "Off\n");
  os << indent << "Compute Cell Normals: " 
     << (this->ComputeCellNormals ? "On\n" : "Off\n");
  os << indent << "Non-manifold Traversal: " 
     << (this->NonManifoldTraversal ? "On\n" : "Off\n");
}