Callbacks to Onyx

Game Engine - Callbacks

A simple start.

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The Onyx scripts used in the game engine can have functions defined that are called when an event happens. For example, OnMultiplayerClientConnected() is called when the client connects succesfully to the server in a multiplayer game.

It is important to know the order in which callbacks are called. This is because your callbacks may depends on certain state (like object position) to have been updated (or not yet).

Racer uses this order (the bold functions are called inside Onyx scripts):

while(simulatedTime<realTime)OnTick();
OnPreFrame() is called for all components
OnPreFrameLate() is called for all components. This would for example be the place where you update a camera (not in OnPreFrame()) to make sure the transform of an object is up-to-date.
Render a frame.

Internally (in the C++ core) there is a slightly more complex loop to keep the scripting side and C++ sync:

while(simulatedTime<realTime){ OnTick(); StepPhysicsEngine(); }
OnPreFrame() is called for all components
OnPreFrameLate() is called for all components. This would for example be the place where you update a camera (not in OnPreFrame()) to make sure the transform of an object is up-to-date.
Render a frame.

These callbacks can be defined in any Onyx script (and are called automatically by the engine):

Group	Function prototype	Description
Entities	OnEntityCreated(int eid)	called when an entity is spawned on the machine. Called on multiplayer servers and clients.
Graphics	OnPreFrame()	Called before a frame is rendered. Here it is time to setup the transform of objects.
	OnPreFrameLate()	Called later than OnPreFrame, but still before a frame render. This is the place to setup the camera.
Multiplayer	OnMultiplayerClientConnected()	Called on the client when a client connects succesfully to the multiplayer server.
Timing	OnTick()	Called at the physics frequency
Events	OnTriggerLine(int n)	Called when a tracked entity crosses a triggerline.
	OnTrackLoaded()	Called when a track has been loaded.

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(last updated January 13, 2014 )