Time and Physics Steps
Trial includes its own way to deal with physics updates and time passage separate from the rendering. This logic is typically handled by the
render-loop class, which is a superclass of
display (and thus
render-loop keeps a separate thread to perform physics steps and rendering, and to keep the main thread free to handle inputs and OS interactions.
render-loop will periodically call
update on itself in a fixed time step, determined by
delta-time, defaulting to 0.01s. This is suitable for physics updates. Despite the fact that the time step (
dt) is kept fixed, you should nevertheless not rely on that, and instead only rely on the
dt value for all your physics updates. This will make your code more robust and allow the implementation of features such as time slowdown or speedup. The
update calls will typically happen in lock-step with real-time. If rendering causes things to slow down beyond real-time,
update will be repeatedly called until physics have "caught up", unless the delay is beyond ten seconds, in which case lost time is simply dropped.
render-loop will also call
render on itself as frequently as possible by default. You can force a frame limit using
target-frame-rate, in which case a fast system will slow itself down automatically to avoid overuse of resources. Another way to restrict frame rate is to enable
vsync on the context, though it should be left up to the end user to choose whether to activate vsync or to impose a frame limit.
main the calls to
update are translated to a
tick event, which carries the associated information:
ttA double-float holding the total physics run-time so far.
dtA single-float holding the period this update should advance physics by.
fcAn integer holding the count of updates so far.
update, events are then issued and processed. This will cause the
tick to be processed last, after any other pending events, though before any events issued during the event processing itself.