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

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

#include "vtkDoubleArray.h"
#include "vtkFloatArray.h"
#include "vtkMath.h"
#include "vtkInformation.h"
#include "vtkInformationVector.h"
#include "vtkObjectFactory.h"
#include "vtkPointData.h"
#include "vtkPolyData.h"
#include "vtkStreamingDemandDrivenPipeline.h"
#include "vtkStructuredPoints.h"

vtkCxxRevisionMacro(vtkSubPixelPositionEdgels, "$Revision: 1.48 $");
vtkStandardNewMacro(vtkSubPixelPositionEdgels);

vtkSubPixelPositionEdgels::vtkSubPixelPositionEdgels()
{
  this->TargetFlag = 0;
  this->TargetValue = 0.0;

  this->SetNumberOfInputPorts(2);
}

vtkSubPixelPositionEdgels::~vtkSubPixelPositionEdgels()
{
}

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

  // get the input and ouptut
  vtkPolyData *input = vtkPolyData::SafeDownCast(
    inInfo->Get(vtkDataObject::DATA_OBJECT()));
  vtkStructuredPoints *gradMaps = vtkStructuredPoints::SafeDownCast(
    gradMapsInfo->Get(vtkDataObject::DATA_OBJECT()));
  vtkPolyData *output = vtkPolyData::SafeDownCast(
    outInfo->Get(vtkDataObject::DATA_OBJECT()));
  
  vtkIdType numPts=input->GetNumberOfPoints();
  vtkPoints *newPts;
  vtkDoubleArray *newNormals;
  vtkPoints *inPts;
  vtkDataArray *inVectors;
  vtkIdType ptId;
  float *MapData = 0;
  double *DMapData = 0;
  double pnt[3];
  int *dimensions;
  double result[3], resultNormal[3];
  double *spacing, *origin;
  
  vtkDebugMacro(<<"SubPixelPositioning Edgels");

  if ( numPts < 1 || (inPts=input->GetPoints()) == NULL )
    {
    vtkErrorMacro(<<"No data to fit!");
    return 1;
    }

  newPts = vtkPoints::New();
  newNormals = vtkDoubleArray::New();
  newNormals->SetNumberOfComponents(3);
  
  dimensions = gradMaps->GetDimensions();
  spacing = gradMaps->GetSpacing();
  origin = gradMaps->GetOrigin();
  if (vtkDoubleArray::SafeDownCast(gradMaps->GetPointData()->GetScalars()))
    {
    DMapData = vtkDoubleArray::SafeDownCast(gradMaps->GetPointData()
                                            ->GetScalars())->GetPointer(0);
    }
  else if (vtkFloatArray::SafeDownCast(gradMaps->GetPointData()->GetScalars()))
    {
    MapData = vtkFloatArray::SafeDownCast(gradMaps->GetPointData()
                                          ->GetScalars())->GetPointer(0);
    }
  
  inVectors = gradMaps->GetPointData()->GetVectors();

  //
  // Loop over all points, adjusting locations
  //
  for (ptId=0; ptId < inPts->GetNumberOfPoints(); ptId++)
    {
    inPts->GetPoint(ptId,pnt);
    pnt[0] = (pnt[0] - origin[0])/spacing[0];
    pnt[1] = (pnt[1] - origin[1])/spacing[1];
    pnt[2] = (pnt[2] - origin[2])/spacing[2];
    if (MapData)
      {
      this->Move(dimensions[0],dimensions[1],dimensions[2],
                 (int)(pnt[0]+0.5),(int)(pnt[1]+0.5),MapData,
                 inVectors, result, (int)(pnt[2]+0.5), spacing,
                 resultNormal);
      }
    else if (DMapData)
      {
      this->Move(dimensions[0],dimensions[1],dimensions[2],
                 (int)(pnt[0]+0.5),(int)(pnt[1]+0.5),DMapData,
                 inVectors, result, (int)(pnt[2]+0.5), spacing,
                 resultNormal);
      }
    result[0] = result[0]*spacing[0] + origin[0];
    result[1] = result[1]*spacing[1] + origin[1];
    result[2] = result[2]*spacing[2] + origin[2];
    newPts->InsertNextPoint(result);
    newNormals->InsertNextTuple(resultNormal);
    }
  
  output->CopyStructure(input);
  output->GetPointData()->CopyNormalsOff();
  output->GetPointData()->PassData(input->GetPointData());
  output->GetPointData()->SetNormals(newNormals);
  output->SetPoints(newPts);
  newPts->Delete();
  newNormals->Delete();

  return 1;
}

void vtkSubPixelPositionEdgels::Move(int xdim, int ydim, int zdim,
                                     int x, int y,
                                     double *img, vtkDataArray *inVecs, 
                                     double *result, int z, double *spacing,
                                     double *resultNormal)
{
  int ypos;
  vtkIdType zpos;
  double vec[3];
  double valn, valp;
  double mag;
  double a,b,c;
  double xp, yp, zp;
  double xn, yn, zn;
  int xi, yi, zi, i;
  
  zpos = z*xdim*ydim;

  ypos = y*xdim;
  
  // handle the 2d case
  if (zdim < 2)
    {
    if (x < 1 || y < 1 || x >= (xdim-2) || y >= (ydim -2))
      {
      result[0] = x;
      result[1] = y;
      result[2] = z;
      // if the point of off of the grad map just make up a value
      if (x < 0 || y < 0 || x > xdim || y > ydim)
        {
        resultNormal[0] = 1;
        resultNormal[1] = 0;
        resultNormal[2] = 0;        
        }
      else
        {
        for (i = 0; i < 3; i++)
          {
          resultNormal[i] = 
            inVecs->GetTuple(x + xdim*y)[i];
          }
        vtkMath::Normalize(resultNormal);
        }
      }
    else 
      {
      // first get the orientation
      inVecs->GetTuple(x+ypos,vec);
      vec[0] = vec[0]*spacing[0];
      vec[1] = vec[1]*spacing[1];
      vec[2] = 0;
      vtkMath::Normalize(vec);
      mag = img[x+ypos];
      
      // compute the sample points
      xp = (double)x + vec[0];
      yp = (double)y + vec[1];
      xn = (double)x - vec[0];
      yn = (double)y - vec[1];
      
      // compute their values
      xi = (int)xp;
      yi = (int)yp;
      valp = 
        img[xi +xdim*yi]*(1.0 -xp +xi)*(1.0 -yp +yi) +
        img[1 +xi + xdim*yi]*(xp -xi)*(1.0 -yp +yi) +
        img[xi +xdim*(yi +1)]*(1.0 -xp +xi)*(yp -yi) +
        img[1 + xi + xdim*(yi +1)]*(xp -xi)*(yp -yi);
      
      xi = (int)xn;
      yi = (int)yn;
      valn = 
        img[xi +xdim*yi]*(1.0 -xn +xi)*(1.0 -yn +yi) +
        img[1 + xi +xdim*yi]*(xn -xi)*(1.0 -yn +yi) +
        img[xi + xdim*(yi +1)]*(1.0 -xn +xi)*(yn -yi) +
        img[1 + xi + xdim*(yi +1)]*(xn -xi)*(yn -yi);
      
      result[0] = x;
      result[1] = y;
      result[2] = z;
      
      // now fit to a parabola and find max
      c = mag;
      b = (valp - valn)/2.0;
      a = (valp - c - b);
      // assign the root to c because MSVC5.0 optimizer has problems with this
      // function
      c = -0.5*b/a;
      if (c > 1.0)
        {
        c = 1.0;
        }
      if (c < -1.0)
        {
        c = -1.0;
        }
      result[0] += vec[0]*c;
      result[1] += vec[1]*c;
      
      // now calc the normal, trilinear interp of vectors
      xi = (int)result[0];
      yi = (int)result[1];
      //zi = (int)result[2];
      xn = result[0];
      yn = result[1];
      //zn = result[2];
      for (i = 0; i < 3; i++)
        {
        resultNormal[i] = 
          inVecs->GetTuple(xi + xdim*yi)[i] * (1.0 -xn +xi)*(1.0 -yn +yi) +
          inVecs->GetTuple(1 + xi + xdim*yi)[i] * (xn -xi)*(1.0 -yn +yi) +
          inVecs->GetTuple(xi + xdim*(yi +1))[i] * (1.0 -xn +xi)*(yn -yi) +
          inVecs->GetTuple(1 + xi + xdim*(yi +1))[i] * (xn -xi)*(yn -yi);
        }
      vtkMath::Normalize(resultNormal);
      }
    }
  else
    {
    if (x < 1 || y < 1 || z < 1 || 
        x >= (xdim-2) || y >= (ydim -2) || z >= (zdim -2))
      {
      result[0] = x;
      result[1] = y;
      result[2] = z;
      if (x < 0 || y < 0 || z < 0 || 
          x > xdim || y > ydim || z > zdim)
        {
        resultNormal[0] = 1;
        resultNormal[1] = 1;
        resultNormal[2] = 1;
        }
      else
        {
        for (i = 0; i < 3; i++)
          {
          resultNormal[i] = 
            inVecs->GetTuple(x + xdim*y + xdim*ydim*z)[i];
          }
        vtkMath::Normalize(resultNormal);
        }
      }
    else 
      {
      // first get the orientation
      inVecs->GetTuple(x+ypos+zpos,vec);
      vec[0] = vec[0]*spacing[0];
      vec[1] = vec[1]*spacing[1];
      vec[2] = vec[2]*spacing[2];
      vtkMath::Normalize(vec);
      mag = img[x+ypos+zpos];
      
      // compute the sample points
      xp = (double)x + vec[0];
      yp = (double)y + vec[1];
      zp = (double)z + vec[2];
      xn = (double)x - vec[0];
      yn = (double)y - vec[1];
      zn = (double)z - vec[2];
      
      // compute their values
      xi = (int)xp;
      yi = (int)yp;
      zi = (int)zp;

      // This set of statements used to be one statement. It was broken up
      // due to problems with MSVC 5.0
      valp = 
        img[xi +xdim*(yi +zi*ydim)]*(1.0 -xp +xi)*(1.0 -yp +yi)*(1.0 -zp +zi);
      valp +=
        img[1 +xi + xdim*(yi + zi*ydim)]*(xp -xi)*(1.0 -yp +yi)*(1.0 -zp +zi);
      valp +=
        img[xi +xdim*(yi +1 + zi*ydim)]*(1.0 -xp +xi)*(yp -yi)*(1.0 -zp +zi);
      valp +=
        img[1 + xi + xdim*(yi +1 +zi*ydim)]*(xp -xi)*(yp -yi)*(1.0 -zp +zi);
      valp +=
        img[xi +xdim*(yi + (zi+1)*ydim)]*(1.0 -xp +xi)*(1.0 -yp +yi)*(zp -zi);
      valp +=
        img[1 + xi + xdim*(yi + (zi+1)*ydim)]*(xp -xi)*(1.0 -yp +yi)*(zp -zi);
      valp +=
        img[xi + xdim*(yi +1 + (zi+1)*ydim)]*(1.0 -xp +xi)*(yp -yi)*(zp -zi);
      valp +=
        img[1 + xi + xdim*(yi +1 +(zi+1)*ydim)]*(xp -xi)*(yp -yi)*(zp -zi);
      
      xi = (int)xn;
      yi = (int)yn;
      zi = (int)zn;
      // This set of statements used to be one statement. It was broken up
      // due to problems with MSVC 5.0
      valn = 
        img[xi +xdim*(yi +zi*ydim)]*(1.0 -xn +xi)*(1.0 -yn +yi)*(1.0 -zn +zi);
      valn +=
        img[1 + xi +xdim*(yi + zi*ydim)]*(xn -xi)*(1.0 -yn +yi)*(1.0 -zn +zi);
      valn +=
        img[xi + xdim*(yi +1 + zi*ydim)]*(1.0 -xn +xi)*(yn -yi)*(1.0 -zn +zi);
      valn +=
        img[1 + xi + xdim*(yi +1 +zi*ydim)]*(xn -xi)*(yn -yi)*(1.0 -zn +zi);
      valn +=
        img[xi +xdim*(yi + (zi+1)*ydim)]*(1.0 -xn +xi)*(1.0 -yn +yi)*(zn -zi);
      valn +=
        img[1 + xi + xdim*(yi + (zi+1)*ydim)]*(xn -xi)*(1.0 -yn +yi)*(zn -zi);
      valn +=
        img[xi + xdim*(yi +1 + (zi+1)*ydim)]*(1.0 -xn +xi)*(yn -yi)*(zn -zi);
      valn +=
        img[1 + xi + xdim*(yi +1 +(zi+1)*ydim)]*(xn -xi)*(yn -yi)*(zn -zi);
      
      result[0] = x;
      result[1] = y;
      result[2] = z;

      if (this->TargetFlag)
        {
        // For target, do a simple linear interpolation to avoid binomial.
        c = mag;
        if (c == this->TargetValue)
          {
          c = 0.0;
          }
        else if ((this->TargetValue < c && valp < c) ||
                 (this->TargetValue > c && valp > c))
          {
          c = (this->TargetValue - c) / (valp - c);
          }
        else if ((this->TargetValue < c && valn < c) ||
                 (this->TargetValue < c && valn > c))
          {
          c = (this->TargetValue - c) / (c - valn);
          }
        else
          {
          c = 0.0;
          }
        }
      else 
        {
        // now fit to a parabola and find max
        c = mag;
        b = (valp - valn)/2.0;
        a = (valp - c - b);
        
        //assign the root to c because MSVC5.0 optimizer has problems with this
        // function
        c = -0.5*b/a;
        }
      
      if (c > 1.0) 
        {
        c = 1.0;
        }
      if (c < -1.0) 
        {
        c = -1.0;
        }
      result[0] = result[0] + vec[0]*c;
      result[1] = result[1] + vec[1]*c;
      result[2] = result[2] + vec[2]*c;

      // now calc the normal, trilinear interp of vectors
      xi = (int)result[0];
      yi = (int)result[1];
      zi = (int)result[2];
      xn = result[0];
      yn = result[1];
      zn = result[2];

      for (i = 0; i < 3; i++)
        {
        resultNormal[i] = 
          inVecs->GetTuple(xi + xdim*(yi + zi*ydim))[i] * 
          (1.0 -xn +xi)*(1.0 -yn +yi)*(1.0 -zn +zi) +
          inVecs->GetTuple(1 + xi + xdim*(yi + zi*ydim))[i] *
          (xn -xi)*(1.0 -yn +yi)*(1.0 -zn +zi) +
          inVecs->GetTuple(xi + xdim*(yi +1 + zi*ydim))[i] *
          (1.0 -xn +xi)*(yn -yi)*(1.0 -zn +zi) +
          inVecs->GetTuple(1 + xi + xdim*(yi +1 +zi*ydim))[i] *
          (xn -xi)*(yn -yi)*(1.0 -zn +zi) +
          inVecs->GetTuple(xi + xdim*(yi + (zi+1)*ydim))[i] *
          (1.0 -xn +xi)*(1.0 -yn +yi)*(zn -zi) +
          inVecs->GetTuple(1 + xi + xdim*(yi + (zi+1)*ydim))[i] * 
          (xn -xi)*(1.0 -yn +yi)*(zn -zi) +
          inVecs->GetTuple(xi + xdim*(yi +1 + (zi+1)*ydim))[i] *
          (1.0 -xn +xi)*(yn -yi)*(zn -zi) +
          inVecs->GetTuple(1 + xi + xdim*(yi +1 +(zi+1)*ydim))[i] *
          (xn -xi)*(yn -yi)*(zn -zi);
        }
      vtkMath::Normalize(resultNormal);

      }
    }
}

void vtkSubPixelPositionEdgels::Move(int xdim, int ydim, int zdim,
                                     int x, int y,
                                     float *img, vtkDataArray *inVecs, 
                                     double *result, int z, double *spacing,
                                     double *resultNormal)
{
  int ypos;
  vtkIdType zpos;
  double vec[3];
  double valn, valp;
  double mag;
  double a,b,c;
  double xp, yp, zp;
  double xn, yn, zn;
  int xi, yi, zi, i;
  
  zpos = z*xdim*ydim;

  ypos = y*xdim;
  
  // handle the 2d case
  if (zdim < 2)
    {
    if (x < 1 || y < 1 || x >= (xdim-2) || y >= (ydim -2))
      {
      result[0] = x;
      result[1] = y;
      result[2] = z;
      // if the point of off of the grad map just make up a value
      if (x < 0 || y < 0 || x > xdim || y > ydim)
        {
        resultNormal[0] = 1;
        resultNormal[1] = 0;
        resultNormal[2] = 0;        
        }
      else
        {
        for (i = 0; i < 3; i++)
          {
          resultNormal[i] = 
            inVecs->GetTuple(x + xdim*y)[i];
          }
        vtkMath::Normalize(resultNormal);
        }
      }
    else 
      {
      // first get the orientation
      inVecs->GetTuple(x+ypos,vec);
      vec[0] = vec[0]*spacing[0];
      vec[1] = vec[1]*spacing[1];
      vec[2] = 0;
      vtkMath::Normalize(vec);
      mag = img[x+ypos];
      
      // compute the sample points
      xp = (double)x + vec[0];
      yp = (double)y + vec[1];
      xn = (double)x - vec[0];
      yn = (double)y - vec[1];
      
      // compute their values
      xi = (int)xp;
      yi = (int)yp;
      valp = 
        img[xi +xdim*yi]*(1.0 -xp +xi)*(1.0 -yp +yi) +
        img[1 +xi + xdim*yi]*(xp -xi)*(1.0 -yp +yi) +
        img[xi +xdim*(yi +1)]*(1.0 -xp +xi)*(yp -yi) +
        img[1 + xi + xdim*(yi +1)]*(xp -xi)*(yp -yi);
      
      xi = (int)xn;
      yi = (int)yn;
      valn = 
        img[xi +xdim*yi]*(1.0 -xn +xi)*(1.0 -yn +yi) +
        img[1 + xi +xdim*yi]*(xn -xi)*(1.0 -yn +yi) +
        img[xi + xdim*(yi +1)]*(1.0 -xn +xi)*(yn -yi) +
        img[1 + xi + xdim*(yi +1)]*(xn -xi)*(yn -yi);
      
      result[0] = x;
      result[1] = y;
      result[2] = z;
      
      // now fit to a parabola and find max
      c = mag;
      b = (valp - valn)/2.0;
      a = (valp - c - b);
      // assign the root to c because MSVC5.0 optimizer has problems with this
      // function
      c = -0.5*b/a;
      if (c > 1.0)
        {
        c = 1.0;
        }
      if (c < -1.0)
        {
        c = -1.0;
        }
      result[0] += vec[0]*c;
      result[1] += vec[1]*c;
      
      // now calc the normal, trilinear interp of vectors
      xi = (int)result[0];
      yi = (int)result[1];
      //zi = (int)result[2];
      xn = result[0];
      yn = result[1];
      //zn = result[2];
      for (i = 0; i < 3; i++)
        {
        resultNormal[i] = 
          inVecs->GetTuple(xi + xdim*yi)[i] * (1.0 -xn +xi)*(1.0 -yn +yi) +
          inVecs->GetTuple(1 + xi + xdim*yi)[i] * (xn -xi)*(1.0 -yn +yi) +
          inVecs->GetTuple(xi + xdim*(yi +1))[i] * (1.0 -xn +xi)*(yn -yi) +
          inVecs->GetTuple(1 + xi + xdim*(yi +1))[i] * (xn -xi)*(yn -yi);
        }
      vtkMath::Normalize(resultNormal);
      }
    }
  else
    {
    if (x < 1 || y < 1 || z < 1 || 
        x >= (xdim-2) || y >= (ydim -2) || z >= (zdim -2))
      {
      result[0] = x;
      result[1] = y;
      result[2] = z;
      if (x < 0 || y < 0 || z < 0 || 
          x > xdim || y > ydim || z > zdim)
        {
        resultNormal[0] = 1;
        resultNormal[1] = 1;
        resultNormal[2] = 1;
        }
      else
        {
        for (i = 0; i < 3; i++)
          {
          resultNormal[i] = 
            inVecs->GetTuple(x + xdim*y + xdim*ydim*z)[i];
          }
        vtkMath::Normalize(resultNormal);
        }
      }
    else 
      {
      // first get the orientation
      inVecs->GetTuple(x+ypos+zpos,vec);
      vec[0] = vec[0]*spacing[0];
      vec[1] = vec[1]*spacing[1];
      vec[2] = vec[2]*spacing[2];
      vtkMath::Normalize(vec);
      mag = img[x+ypos+zpos];
      
      // compute the sample points
      xp = (double)x + vec[0];
      yp = (double)y + vec[1];
      zp = (double)z + vec[2];
      xn = (double)x - vec[0];
      yn = (double)y - vec[1];
      zn = (double)z - vec[2];
      
      // compute their values
      xi = (int)xp;
      yi = (int)yp;
      zi = (int)zp;

      // This set of statements used to be one statement. It was broken up
      // due to problems with MSVC 5.0
      valp = 
        img[xi +xdim*(yi +zi*ydim)]*(1.0 -xp +xi)*(1.0 -yp +yi)*(1.0 -zp +zi);
      valp +=
        img[1 +xi + xdim*(yi + zi*ydim)]*(xp -xi)*(1.0 -yp +yi)*(1.0 -zp +zi);
      valp +=
        img[xi +xdim*(yi +1 + zi*ydim)]*(1.0 -xp +xi)*(yp -yi)*(1.0 -zp +zi);
      valp +=
        img[1 + xi + xdim*(yi +1 +zi*ydim)]*(xp -xi)*(yp -yi)*(1.0 -zp +zi);
      valp +=
        img[xi +xdim*(yi + (zi+1)*ydim)]*(1.0 -xp +xi)*(1.0 -yp +yi)*(zp -zi);
      valp +=
        img[1 + xi + xdim*(yi + (zi+1)*ydim)]*(xp -xi)*(1.0 -yp +yi)*(zp -zi);
      valp +=
        img[xi + xdim*(yi +1 + (zi+1)*ydim)]*(1.0 -xp +xi)*(yp -yi)*(zp -zi);
      valp +=
        img[1 + xi + xdim*(yi +1 +(zi+1)*ydim)]*(xp -xi)*(yp -yi)*(zp -zi);
      
      xi = (int)xn;
      yi = (int)yn;
      zi = (int)zn;
      // This set of statements used to be one statement. It was broken up
      // due to problems with MSVC 5.0
      valn = 
        img[xi +xdim*(yi +zi*ydim)]*(1.0 -xn +xi)*(1.0 -yn +yi)*(1.0 -zn +zi);
      valn +=
        img[1 + xi +xdim*(yi + zi*ydim)]*(xn -xi)*(1.0 -yn +yi)*(1.0 -zn +zi);
      valn +=
        img[xi + xdim*(yi +1 + zi*ydim)]*(1.0 -xn +xi)*(yn -yi)*(1.0 -zn +zi);
      valn +=
        img[1 + xi + xdim*(yi +1 +zi*ydim)]*(xn -xi)*(yn -yi)*(1.0 -zn +zi);
      valn +=
        img[xi +xdim*(yi + (zi+1)*ydim)]*(1.0 -xn +xi)*(1.0 -yn +yi)*(zn -zi);
      valn +=
        img[1 + xi + xdim*(yi + (zi+1)*ydim)]*(xn -xi)*(1.0 -yn +yi)*(zn -zi);
      valn +=
        img[xi + xdim*(yi +1 + (zi+1)*ydim)]*(1.0 -xn +xi)*(yn -yi)*(zn -zi);
      valn +=
        img[1 + xi + xdim*(yi +1 +(zi+1)*ydim)]*(xn -xi)*(yn -yi)*(zn -zi);
      
      result[0] = x;
      result[1] = y;
      result[2] = z;

      if (this->TargetFlag)
        {
        // For target, do a simple linear interpolation to avoid binomial.
        c = mag;
        if (c == this->TargetValue)
          {
          c = 0.0;
          }
        else if ((this->TargetValue < c && valp < c) ||
                 (this->TargetValue > c && valp > c))
          {
          c = (this->TargetValue - c) / (valp - c);
          }
        else if ((this->TargetValue < c && valn < c) ||
                 (this->TargetValue < c && valn > c))
          {
          c = (this->TargetValue - c) / (c - valn);
          }
        else
          {
          c = 0.0;
          }
        }
      else 
        {
        // now fit to a parabola and find max
        c = mag;
        b = (valp - valn)/2.0;
        a = (valp - c - b);
        
        //assign the root to c because MSVC5.0 optimizer has problems with this
        // function
        c = -0.5*b/a;
        }
      
      if (c > 1.0) 
        {
        c = 1.0;
        }
      if (c < -1.0) 
        {
        c = -1.0;
        }
      result[0] = result[0] + vec[0]*c;
      result[1] = result[1] + vec[1]*c;
      result[2] = result[2] + vec[2]*c;

      // now calc the normal, trilinear interp of vectors
      xi = (int)result[0];
      yi = (int)result[1];
      zi = (int)result[2];
      xn = result[0];
      yn = result[1];
      zn = result[2];

      for (i = 0; i < 3; i++)
        {
        resultNormal[i] = 
          inVecs->GetTuple(xi + xdim*(yi + zi*ydim))[i] * 
          (1.0 -xn +xi)*(1.0 -yn +yi)*(1.0 -zn +zi) +
          inVecs->GetTuple(1 + xi + xdim*(yi + zi*ydim))[i] *
          (xn -xi)*(1.0 -yn +yi)*(1.0 -zn +zi) +
          inVecs->GetTuple(xi + xdim*(yi +1 + zi*ydim))[i] *
          (1.0 -xn +xi)*(yn -yi)*(1.0 -zn +zi) +
          inVecs->GetTuple(1 + xi + xdim*(yi +1 +zi*ydim))[i] *
          (xn -xi)*(yn -yi)*(1.0 -zn +zi) +
          inVecs->GetTuple(xi + xdim*(yi + (zi+1)*ydim))[i] *
          (1.0 -xn +xi)*(1.0 -yn +yi)*(zn -zi) +
          inVecs->GetTuple(1 + xi + xdim*(yi + (zi+1)*ydim))[i] * 
          (xn -xi)*(1.0 -yn +yi)*(zn -zi) +
          inVecs->GetTuple(xi + xdim*(yi +1 + (zi+1)*ydim))[i] *
          (1.0 -xn +xi)*(yn -yi)*(zn -zi) +
          inVecs->GetTuple(1 + xi + xdim*(yi +1 +(zi+1)*ydim))[i] *
          (xn -xi)*(yn -yi)*(zn -zi);
        }
      vtkMath::Normalize(resultNormal);

      }
    }
}

void vtkSubPixelPositionEdgels::SetGradMaps(vtkStructuredPoints *gm)
{
  this->SetInput(1, gm);
}

vtkStructuredPoints *vtkSubPixelPositionEdgels::GetGradMaps()
{
  if (this->GetNumberOfInputConnections(1) < 1)
    {
    return NULL;
    }
  return vtkStructuredPoints::SafeDownCast(
    this->GetExecutive()->GetInputData(1, 0));
}

int vtkSubPixelPositionEdgels::FillInputPortInformation(int port,
                                                        vtkInformation *info)
{
  if (port == 1)
    {
    info->Set(vtkAlgorithm::INPUT_REQUIRED_DATA_TYPE(), "vtkStructuredPoints");
    return 1;
    }

  return this->Superclass::FillInputPortInformation(port, info);
}

// Print the state of the class.
void vtkSubPixelPositionEdgels::PrintSelf(ostream& os, vtkIndent indent)
{
  this->Superclass::PrintSelf(os,indent);

  if ( this->GetGradMaps() )
    {
    os << indent << "Gradient Data: " << this->GetGradMaps() << "\n";
    }
  else
    {
    os << indent << "Gradient Data: (none)\n";
    }
  
  os << indent << "TargetFlag: " << this->TargetFlag << endl;
  os << indent << "TargetValue: " << this->TargetValue << endl;
}