Method EvaluateGradient

Common/DataModel/vtkImplicitVolume.cxx:97–144

------------------------------------------------------------------------------ Evaluate ImplicitVolume gradient.

//------------------------------------------------------------------------------
// Evaluate ImplicitVolume gradient.
void vtkImplicitVolume::EvaluateGradient(double x[3], double n[3])
{
  vtkDataArray* scalars;
  int i, ijk[3];
  double pcoords[3], weights[8], *v;
  vtkDoubleArray* gradient;

  // See if a volume is defined
  if (!this->Volume || !(scalars = this->Volume->GetPointData()->GetScalars()))
  {
    vtkErrorMacro(
      << "Can't evaluate gradient: either volume is missing or volume has no point data");
    for (i = 0; i < 3; i++)
    {
      n[i] = this->OutGradient[i];
    }
    return;
  }

  gradient = vtkDoubleArray::New();
  gradient->SetNumberOfComponents(3);
  gradient->SetNumberOfTuples(8);

  // Find the cell that contains xyz and get it
  if (this->Volume->ComputeStructuredCoordinates(x, ijk, pcoords))
  {
    vtkVoxel::InterpolationFunctions(pcoords, weights);
    this->Volume->GetVoxelGradient(ijk[0], ijk[1], ijk[2], scalars, gradient);

    n[0] = n[1] = n[2] = 0.0;
    for (i = 0; i < 8; i++)
    {
      v = gradient->GetTuple(i);
      n[0] += v[0] * weights[i];
      n[1] += v[1] * weights[i];
      n[2] += v[2] * weights[i];
    }
  }

  else
  { // use outside value
    for (i = 0; i < 3; i++)
    {
      n[i] = this->OutGradient[i];
    }
  }
  gradient->Delete();
}

//------------------------------------------------------------------------------
void vtkImplicitVolume::PrintSelf(ostream& os, vtkIndent indent)