centerOfViewTickable.h

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/******************************************************************************
** Copyright (c) 2025 MAK Technologies
** All rights reserved.
******************************************************************************/
 
//! \file centerOfViewTickable.h
//! \brief Defines a tickable component that centers the view on an entity
//!
//! This file contains the DtCenterOfViewTickable class which provides functionality
//! to keep the camera view centered on a specified entity. It periodically updates
//! the view center point to follow the target entity's position.
 
#pragma once
 
#include "vrePlayerStation/export.h"
 
#include <vrvCore/DtTickable.h>
 
namespace makVrv
{
class DtSceneObjectAgent;
class DtChannelManager;
class DtChannel;
} // namespace makVrv
 
namespace makVre
{
//! \brief Tickable component that keeps the view centered on an entity
//!
//! DtCenterOfViewTickable is a component that updates the display channels
//! to keep the view centered on a specified scene object (typically an entity).
//! It inherits from DtTickable, allowing it to receive regular update calls
//! from the display engine's main loop. This is useful for keeping the camera
//! focused on a moving entity, such as the player's vehicle or avatar.
class PLAYERSTATION_DLL DtCenterOfViewTickable : public makVrv::DtTickable
{
public:
   //! \brief Constructor
   //! \param de Reference to the display engine
   //!
   //! Creates a new center-of-view tickable component associated with the
   //! specified display engine. The component starts without a target scene object.
   DtCenterOfViewTickable(makVrv::DtDe& de);
 
   //! \brief Virtual destructor
   //!
   //! Ensures proper cleanup of resources used by derived classes.
   virtual ~DtCenterOfViewTickable() override;
 
   //! \brief Updates the center of view
   //! \param tNow Current simulation time
   //!
   //! Called by the tickable manager to update the view center. This method
   //! updates the view to keep it centered on the target scene object.
   //! If no scene object is set, this method does nothing.
   virtual void update(DtTime tNow) override;
 
   //! \brief Checks if an update is needed
   //! \param tNow Current simulation time
   //! \return True if an update should be performed, false otherwise
   //!
   //! Determines whether the view center needs to be updated at the current time.
   //! This helps optimize performance by avoiding unnecessary updates.
   virtual bool needsUpdate(DtTime tNow) override;
 
   //! \brief Sets the target scene object
   //! \param obj Pointer to the scene object to center on
   //!
   //! Sets the scene object that the view should be centered on. This can be
   //! changed at any time to switch the focus to a different entity. Setting
   //! this to NULL disables the centering functionality.
   virtual void setSceneObject(makVrv::DtSceneObjectAgent* obj);
 
protected:
   //! \brief Performs the actual view update
   //! \param mgr Pointer to the channel manager
   //! \param channel Pointer to the channel being updated
   //!
   //! Internal method that performs the actual work of updating a specific
   //! display channel to center on the target scene object. This method is
   //! called for each relevant channel by the update method.
   virtual void actualUpdate(makVrv::DtChannelManager* mgr, makVrv::DtChannel* channel);
 
   //! \brief Time of the last update
   //!
   //! Stores the simulation time of the last performed update to control
   //! update frequency and avoid redundant updates.
   DtTime myLastUpdatedTime;
 
   //! \brief Reference to the display engine
   //!
   //! Provides access to channels, scene objects, and other display resources.
   makVrv::DtDe& myDe;
 
   //! \brief Target scene object to center on
   //!
   //! The scene object that the view should be centered on. May be NULL if
   //! no centering is currently desired.
   makVrv::DtSceneObjectAgent* mySceneObject;
};
} // namespace makVre