vtk mpr軸旋轉核心部分

//----------------------------------------------------------------------
void vtkResliceCursorLineRepresentation::WidgetInteraction(double e[2])
{
  vtkResliceCursor *rc = this->GetResliceCursor();

  if (this->ManipulationMode == WindowLevelling)
  {
    this->WindowLevel(e[0], e[1]);
    this->LastEventPosition[0] = e[0];
    this->LastEventPosition[1] = e[1];
    return;
  }

  // Depending on the state, different motions are allowed.

  if ( this->InteractionState == Outside || ! this->Renderer || !rc )
  {
    this->LastEventPosition[0] = e[0];
    this->LastEventPosition[1] = e[1];
    return;
  }


  if (rc->GetThickMode() &&
        this->ManipulationMode ==
          vtkResliceCursorRepresentation::ResizeThickness)
  {

    double sf = 1.0;

    // Compute the scale factor
    int *size = this->Renderer->GetSize();
    double dPos = e[1]-this->LastEventPosition[1];
    sf *= (1.0 + 2.0*(dPos / size[1])); //scale factor of 2.0 is arbitrary

    double thickness[3];
    rc->GetThickness(thickness);
    rc->SetThickness( thickness[0] * sf,
                      thickness[1] * sf,
                      thickness[2] * sf );

    this->LastEventPosition[0] = e[0];
    this->LastEventPosition[1] = e[1];

    return;
  }

  // depending on the state, perform different operations
  //
  // 1. Translation

  if ( this->InteractionState == OnCenter && !this->Modifier )
  {

    // Intersect with the viewing vector. We will use this point and the
    // start event point to compute an offset vector to translate the
    // center by.

    double intersectionPos[3], newCenter[3];
    this->Picker->Pick( e, intersectionPos, this->Renderer );

    // Offset the center by this vector.

    for (int i = 0; i < 3; i++)
    {
      newCenter[i] = this->StartCenterPosition[i] +
        intersectionPos[i] - this->StartPickPosition[i];
    }

    rc->SetCenter(newCenter);
  }


  // 2. Rotation of axis 1

  if ( this->InteractionState == OnAxis1 && !this->Modifier )
  {
    this->RotateAxis( e,
        this->ResliceCursorActor->GetCursorAlgorithm()->GetPlaneAxis1() );
  }

  // 3. Rotation of axis 2

  if ( this->InteractionState == OnAxis2 && !this->Modifier )
  {
    this->RotateAxis( e,
        this->ResliceCursorActor->GetCursorAlgorithm()->GetPlaneAxis2() );
  }

  // 4. Rotation of both axes

  if ( (this->InteractionState == OnAxis2 ||
        this->InteractionState == OnAxis1) && this->Modifier )
  {
    // Rotate both by the same angle
    const double angle = this->RotateAxis( e,
        this->ResliceCursorActor->GetCursorAlgorithm()->GetPlaneAxis1() );
    this->RotateAxis(
        this->ResliceCursorActor->GetCursorAlgorithm()->GetPlaneAxis2(), angle );
  }

  this->LastEventPosition[0] = e[0];
  this->LastEventPosition[1] = e[1];
}