Method UpdateTensorFromWidget

Interaction/Widgets/vtkTensorRepresentation.cxx:1272–1316

------------------------------------------------------------------------------ Update the tensor ellipsoid, and associated tensor data (e.g., eigenvalues) from the current widget/representation state.

// Update the tensor ellipsoid, and associated tensor data (e.g., eigenvalues)
// from the current widget/representation state.
void vtkTensorRepresentation::UpdateTensorFromWidget()
{
  // Obtain the points defining the representation
  double* pts = static_cast<vtkDoubleArray*>(this->Points->GetData())->GetPointer(0);
  double* center = pts + 3 * 14;
  double* x = pts + 3 * 9;
  double* y = pts + 3 * 11;
  double* z = pts + 3 * 13;

  // Gather information about the representation: size (norm) of semi-axes;
  // and the semi-axes vectors. These are the eigenvectors and values of the
  // tensor.
  double tensor[3][3];
  for (auto i = 0; i < 3; ++i)
  {
    tensor[i][0] = x[i] - center[i];
    tensor[i][1] = y[i] - center[i];
    tensor[i][2] = z[i] - center[i];
  }

  // Use the internal transforms to perform the transformation of the
  // ellipsoid.
  this->EllipsoidTransform->Identity();

  // Translate to center of widget
  this->EllipsoidTransform->Translate(center);

  // Next scale and rotate the ellipsoid based on the eigenvectors (which are
  // simply the semi-axes of the widget representation).
  for (auto j = 0; j < 3; ++j)
  {
    for (auto i = 0; i < 3; ++i)
    {
      this->EllipsoidMatrix->Element[i][j] = tensor[i][j];
    }
  }
  this->EllipsoidTransform->Concatenate(this->EllipsoidMatrix);

  // Specify total transformation
  //  this->EllipsoidTransform->Modified();

  // Now update the tensor information
  std::copy(center, center + 3, this->TensorPosition);
  this->UpdateTensorEigenfunctions(tensor);
}

//------------------------------------------------------------------------------
void vtkTensorRepresentation::UpdateTensorEigenfunctions(double tensor[3][3])