text: /*=========================================================================
  
    Program:   Visualization Toolkit
  
    Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
    All rights reserved.
    See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
  
       This software is distributed WITHOUT ANY WARRANTY; without even
       the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
       PURPOSE.  See the above copyright notice for more information.
  
  =========================================================================*/
  /**
   * @class   vtkOpenVRFollower
   * @brief   OpenVR Follower
   *
   * vtkOpenVRFollower a follower that aligns with PhysicalViewUp
   */
  
  #ifndef vtkOpenVRFollower_h
  #define vtkOpenVRFollower_h
  
  #include "vtkFollower.h"
  #include "vtkRenderingOpenVRModule.h" // For export macro
  
  class VTKRENDERINGOPENVR_EXPORT vtkOpenVRFollower : public vtkFollower
  {
  public:
    static vtkOpenVRFollower* New();
    vtkTypeMacro(vtkOpenVRFollower, vtkFollower);
    void PrintSelf(ostream& os, vtkIndent indent) override;
  
    virtual void Render(vtkRenderer* ren) override;
  
    /**
     * Generate the matrix based on ivars. This method overloads its superclasses
     * ComputeMatrix() method due to the special vtkFollower matrix operations.
     */
    void ComputeMatrix() override;
  
  protected:
    vtkOpenVRFollower();
    ~vtkOpenVRFollower();
  
    double LastViewUp[3];
  
  private:
    vtkOpenVRFollower(const vtkOpenVRFollower&) = delete;
    void operator=(const vtkOpenVRFollower&) = delete;
  };
  
  #endif
  