Method InternalUpdate

Common/Transforms/vtkTransform.cxx:145–221

------------------------------------------------------------------------------

//------------------------------------------------------------------------------
void vtkTransform::InternalUpdate()
{
  int i;
  int nTransforms = this->Concatenation->GetNumberOfTransforms();
  int nPreTransforms = this->Concatenation->GetNumberOfPreTransforms();

  // check to see whether someone has been fooling around with our matrix
  int doTheLegacyHack = 0;
  if (this->Matrix->GetMTime() > this->MatrixUpdateMTime)
  {
    vtkDebugMacro(<< "InternalUpdate: this->Matrix was modified by something other than 'this'");

    // check to see if we have any inputs or concatenated transforms
    int isPipelined = (this->Input != nullptr);
    for (i = 0; i < nTransforms && !isPipelined; i++)
    { // the vtkSimpleTransform is just a matrix placeholder,
      // it is not a real transform
      isPipelined = !this->Concatenation->GetTransform(i)->IsA("vtkSimpleTransform");
    }
    // do the legacy hack only if we have no input transforms
    doTheLegacyHack = !isPipelined;
  }

  // copy matrix from input
  if (this->Input)
  {
    this->Matrix->DeepCopy(this->Input->GetMatrix());
    // if inverse flag is set, invert the matrix
    if (this->Concatenation->GetInverseFlag())
    {
      this->Matrix->Invert();
    }
  }
  else if (doTheLegacyHack)
  {
    vtkWarningMacro("InternalUpdate: doing hack to support legacy code.  "
                    "This is deprecated in VTK 4.2.  May be removed in a "
                    "future version.");
    // this heuristic works perfectly if GetMatrix() or GetMatrixPointer()
    // was called immediately prior to the matrix modifications
    // (fortunately, this is almost always the case)
    if (this->Matrix->GetMTime() > this->Concatenation->GetMaxMTime())
    { // don't apply operations that occurred after matrix modification
      nPreTransforms = nTransforms = 0;
    }
  }
  else
  { // otherwise, we start with the identity transform as our base
    this->Matrix->Identity();
  }

  // concatenate PreTransforms
  for (i = nPreTransforms - 1; i >= 0; i--)
  {
    vtkHomogeneousTransform* transform =
      static_cast<vtkHomogeneousTransform*>(this->Concatenation->GetTransform(i));
    vtkMatrix4x4::Multiply4x4(this->Matrix, transform->GetMatrix(), this->Matrix);
  }