Diablo like mouse character lookAt

gistfile1.cpp

void Player::lookAtFromMouse() {
  if (m_pCharacter == NULL) return;
 
  //o-- Get Mouse Position
  CEGUI::Vector2f absMouse = CEGUI::System::getSingleton().getDefaultGUIContext().getMouseCursor().getPosition();
  CEGUI::Vector2f relativeMouse = CEGUI::CoordConverter::screenToWindow(
      *CEGUI::System::getSingleton().getDefaultGUIContext().getRootWindow(),
      absMouse
  );
  
  //o-- Get Screen Coordinates
  R32 screenX = relativeMouse.d_x;
  R32 screenY = relativeMouse.d_y;
 
  //o-- Get Window Size
  R32 windowWidth = CEGUI::CoordConverter::screenToWindowX(
    *CEGUI::System::getSingleton().getDefaultGUIContext().getRootWindow(),
    CEGUI::UDim(1,0)
  );
  R32 windowHeight = CEGUI::CoordConverter::screenToWindowY(
    *CEGUI::System::getSingleton().getDefaultGUIContext().getRootWindow(),
    CEGUI::UDim(1,0)
  );
 
  Ogre::SceneManager *m_pSceneMgr = Ogre::Root::getSingletonPtr()->getSceneManager("SceneManager");
  //o-- Assume we have a valid SceneManager
  if (!m_pSceneMgr) return;
 
  Ogre::Camera *m_pCamera = m_pSceneMgr->getCamera("Camera");
  //o-- Assume we have a valid Camera
  if (!m_pCamera) return;
 
  //o-- Create a Ray
  Ogre::Ray mouseRay = m_pCamera->getCameraToViewportRay(
    screenX / windowWidth,
    screenY / windowHeight
  );
 
  //o-- Create a Plane in Y Axis with Origin as Character Position
  Ogre::Plane characterPlane(Ogre::Vector3::UNIT_Y, m_pCharacter->getPosition() );
   
  //o-- Get an intersection point from Screen to that Plane
  std::pair<bool, Ogre::Real> intersectionResult = mouseRay.intersects(characterPlane);
  if (intersectionResult.first) {
    //o-- Use the intersection point of the plane to calculate the rotation for the character
    Ogre::Vector3 intersectionInWorldCoord = mouseRay.getPoint( intersectionResult.second );
    Ogre::Vector3 lookingAt = intersectionInWorldCoord - m_pCharacter->getPosition();
    Ogre::Vector3 facingTo = Ogre::Vector3::NEGATIVE_UNIT_Z;
    lookingAt.y = 0;
    facingTo.y = 0;
    Ogre::Real mDistance = lookingAt.normalise();
    Ogre::Quaternion newOrientation = facingTo.getRotationTo( lookingAt );
    m_pCharacter->setOrientation( newOrientation ); 
  }
}