Method RequiresEdgeSubdivision

Common/DataModel/vtkAttributesErrorMetric.cxx:66–145

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//------------------------------------------------------------------------------
int vtkAttributesErrorMetric::RequiresEdgeSubdivision(
  double* leftPoint, double* midPoint, double* rightPoint, double alpha)
{
  assert("pre: leftPoint_exists" && leftPoint != nullptr);
  assert("pre: midPoint_exists" && midPoint != nullptr);
  assert("pre: rightPoint_exists" && rightPoint != nullptr);
  assert("pre: clamped_alpha" && alpha > 0 && alpha < 1);

  int result;
  double ae;
  vtkGenericAttributeCollection* ac;

  this->ComputeSquareAbsoluteAttributeTolerance();

  constexpr int ATTRIBUTE_OFFSET = 6;

  ac = this->DataSet->GetAttributes();
  vtkGenericAttribute* a = ac->GetAttribute(ac->GetActiveAttribute());

  if (this->GenericCell->IsAttributeLinear(a))
  {
    // don't need to do anything:
    ae = 0;
  }
  else
  {
    if (ac->GetActiveComponent() >= 0)
    {
      int i = ac->GetAttributeIndex(ac->GetActiveAttribute()) + ac->GetActiveComponent() +
        ATTRIBUTE_OFFSET;
      double tmp = leftPoint[i] + alpha * (rightPoint[i] - leftPoint[i]) - midPoint[i];
      ae = tmp * tmp;
    }
    else // module of the vector
    {
      int i = ac->GetAttributeIndex(ac->GetActiveAttribute()) + ATTRIBUTE_OFFSET;
      int j = 0;
      int c = ac->GetNumberOfComponents();
      double tmp;
#if 0
      // If x and y are two vectors, we compute: ||x|-|y||
      double interpolatedValueMod=0;
      double midValueMod=0;
      while(j<c)
      {
        tmp=leftPoint[i+j]+alpha*(rightPoint[i+j]-leftPoint[i+j]);
        interpolatedValueMod+=tmp*tmp;
        tmp=midPoint[i+j];
        midValueMod+=tmp*tmp;
        ++j;
      }
      tmp=sqrt(midValueMod)-sqrt(interpolatedValueMod);
      ae=tmp*tmp;
#else
      // If x and y are two vectors, we compute: |x-y|
      // We should compute ||x|-|y|| but |x-y| is usually enough
      // and tends to produce less degenerated edges.
      // Remind that: ||x|-|y||<=|x-y|