Ogre::FrameListener Class Reference
[General]

A interface class defining a listener which can be used to receive notifications of frame events. More...

Inheritance diagram for Ogre::FrameListener:

Public Member Functions
virtual bool	frameStarted (const FrameEvent &evt)
	Called when a frame is about to begin rendering.
virtual bool	frameRenderingQueued (const FrameEvent &evt)
	Called after all render targets have had their rendering commands issued, but before render windows have been asked to flip their buffers over.
virtual bool	frameEnded (const FrameEvent &evt)
	Called just after a frame has been rendered.
virtual	~FrameListener ()

Detailed Description

A interface class defining a listener which can be used to receive notifications of frame events.

Remarks:: A 'listener' is an interface designed to be called back when particular events are called. This class defines the interface relating to frame events. In order to receive notifications of frame events, you should create a subclass of FrameListener and override the methods for which you would like to customise the resulting processing. You should then call Root::addFrameListener passing an instance of this class. There is no limit to the number of frame listeners you can register, allowing you to register multiple listeners for different purposes. Frame events only occur when Ogre is in continuous rendering mode, i.e. after Root::startRendering is called. If the application is doing ad-hoc rendering without entering a rendering loop, frame events are not generated. Note that a frame event occurs once for all rendering targets, not once per target.

Definition at line 82 of file OgreFrameListener.h.

virtual Ogre::FrameListener::~FrameListener ( ) [virtual]

Definition at line 133 of file OgreFrameListener.h.

virtual bool Ogre::FrameListener::frameEnded ( const FrameEvent & evt ) [virtual]

Called just after a frame has been rendered.

Remarks:: This event happens after all render targets have been fully updated and the buffers switched.

Returns:: True to continue with the next frame, false to drop out of the rendering loop.

Definition at line 130 of file OgreFrameListener.h.

virtual bool Ogre::FrameListener::frameRenderingQueued ( const FrameEvent & evt ) [virtual]

Called after all render targets have had their rendering commands issued, but before render windows have been asked to flip their buffers over.

Remarks:: The usefulness of this event comes from the fact that rendering commands are queued for the GPU to process. These can take a little while to finish, and so while that is happening the CPU can be doing useful things. Once the request to 'flip buffers' happens, the thread requesting it will block until the GPU is ready, which can waste CPU cycles. Therefore, it is often a good idea to use this callback to perform per-frame processing. Of course because the frame's rendering commands have already been issued, any changes you make will only take effect from the next frame, but in most cases that's not noticeable.