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#[cfg(feature = "bevy_reflect")]
use bevy_reflect::Reflect;
use bevy_utils::{Duration, Instant};
use crate::time::Time;
/// Real time clock representing elapsed wall clock time.
///
/// A specialization of the [`Time`] structure. **For method documentation, see
/// [`Time<Real>#impl-Time<Real>`].**
///
/// It is automatically inserted as a resource by
/// [`TimePlugin`](crate::TimePlugin) and updated with time instants according
/// to [`TimeUpdateStrategy`](crate::TimeUpdateStrategy).
///
/// The [`delta()`](Time::delta) and [`elapsed()`](Time::elapsed) values of this
/// clock should be used for anything which deals specifically with real time
/// (wall clock time). It will not be affected by relative game speed
/// adjustments, pausing or other adjustments.
///
/// The clock does not count time from [`startup()`](Time::startup) to
/// [`first_update()`](Time::first_update()) into elapsed, but instead will
/// start counting time from the first update call. [`delta()`](Time::delta) and
/// [`elapsed()`](Time::elapsed) will report zero on the first update as there
/// is no previous update instant. This means that a [`delta()`](Time::delta) of
/// zero must be handled without errors in application logic, as it may
/// theoretically also happen at other times.
///
/// [`Instant`]s for [`startup()`](Time::startup),
/// [`first_update()`](Time::first_update) and
/// [`last_update()`](Time::last_update) are recorded and accessible.
#[derive(Debug, Copy, Clone)]
#[cfg_attr(feature = "bevy_reflect", derive(Reflect))]
pub struct Real {
startup: Instant,
first_update: Option<Instant>,
last_update: Option<Instant>,
}
impl Default for Real {
fn default() -> Self {
Self {
startup: Instant::now(),
first_update: None,
last_update: None,
}
}
}
impl Time<Real> {
/// Constructs a new `Time<Real>` instance with a specific startup
/// [`Instant`].
pub fn new(startup: Instant) -> Self {
Self::new_with(Real {
startup,
..Default::default()
})
}
/// Updates the internal time measurements.
///
/// Calling this method as part of your app will most likely result in
/// inaccurate timekeeping, as the [`Time`] resource is ordinarily managed
/// by the [`TimePlugin`](crate::TimePlugin).
pub fn update(&mut self) {
let instant = Instant::now();
self.update_with_instant(instant);
}
/// Updates time with a specified [`Duration`].
///
/// This method is provided for use in tests.
///
/// Calling this method as part of your app will most likely result in
/// inaccurate timekeeping, as the [`Time`] resource is ordinarily managed
/// by the [`TimePlugin`](crate::TimePlugin).
pub fn update_with_duration(&mut self, duration: Duration) {
let last_update = self.context().last_update.unwrap_or(self.context().startup);
self.update_with_instant(last_update + duration);
}
/// Updates time with a specified [`Instant`].
///
/// This method is provided for use in tests.
///
/// Calling this method as part of your app will most likely result in inaccurate timekeeping,
/// as the [`Time`] resource is ordinarily managed by the [`TimePlugin`](crate::TimePlugin).
pub fn update_with_instant(&mut self, instant: Instant) {
let Some(last_update) = self.context().last_update else {
let context = self.context_mut();
context.first_update = Some(instant);
context.last_update = Some(instant);
return;
};
let delta = instant - last_update;
self.advance_by(delta);
self.context_mut().last_update = Some(instant);
}
/// Returns the [`Instant`] the clock was created.
///
/// This usually represents when the app was started.
#[inline]
pub fn startup(&self) -> Instant {
self.context().startup
}
/// Returns the [`Instant`] when [`Self::update`] was first called, if it
/// exists.
///
/// This usually represents when the first app update started.
#[inline]
pub fn first_update(&self) -> Option<Instant> {
self.context().first_update
}
/// Returns the [`Instant`] when [`Self::update`] was last called, if it
/// exists.
///
/// This usually represents when the current app update started.
#[inline]
pub fn last_update(&self) -> Option<Instant> {
self.context().last_update
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_update() {
let startup = Instant::now();
let mut time = Time::<Real>::new(startup);
assert_eq!(time.startup(), startup);
assert_eq!(time.first_update(), None);
assert_eq!(time.last_update(), None);
assert_eq!(time.delta(), Duration::ZERO);
assert_eq!(time.elapsed(), Duration::ZERO);
time.update();
assert_ne!(time.first_update(), None);
assert_ne!(time.last_update(), None);
assert_eq!(time.delta(), Duration::ZERO);
assert_eq!(time.elapsed(), Duration::ZERO);
time.update();
assert_ne!(time.first_update(), None);
assert_ne!(time.last_update(), None);
assert_ne!(time.last_update(), time.first_update());
assert_ne!(time.delta(), Duration::ZERO);
assert_eq!(time.elapsed(), time.delta());
let prev_elapsed = time.elapsed();
time.update();
assert_ne!(time.delta(), Duration::ZERO);
assert_eq!(time.elapsed(), prev_elapsed + time.delta());
}
#[test]
fn test_update_with_instant() {
let startup = Instant::now();
let mut time = Time::<Real>::new(startup);
let first_update = Instant::now();
time.update_with_instant(first_update);
assert_eq!(time.startup(), startup);
assert_eq!(time.first_update(), Some(first_update));
assert_eq!(time.last_update(), Some(first_update));
assert_eq!(time.delta(), Duration::ZERO);
assert_eq!(time.elapsed(), Duration::ZERO);
let second_update = Instant::now();
time.update_with_instant(second_update);
assert_eq!(time.first_update(), Some(first_update));
assert_eq!(time.last_update(), Some(second_update));
assert_eq!(time.delta(), second_update - first_update);
assert_eq!(time.elapsed(), second_update - first_update);
let third_update = Instant::now();
time.update_with_instant(third_update);
assert_eq!(time.first_update(), Some(first_update));
assert_eq!(time.last_update(), Some(third_update));
assert_eq!(time.delta(), third_update - second_update);
assert_eq!(time.elapsed(), third_update - first_update);
}
#[test]
fn test_update_with_duration() {
let startup = Instant::now();
let mut time = Time::<Real>::new(startup);
time.update_with_duration(Duration::from_secs(1));
assert_eq!(time.startup(), startup);
assert_eq!(time.first_update(), Some(startup + Duration::from_secs(1)));
assert_eq!(time.last_update(), Some(startup + Duration::from_secs(1)));
assert_eq!(time.delta(), Duration::ZERO);
assert_eq!(time.elapsed(), Duration::ZERO);
time.update_with_duration(Duration::from_secs(1));
assert_eq!(time.first_update(), Some(startup + Duration::from_secs(1)));
assert_eq!(time.last_update(), Some(startup + Duration::from_secs(2)));
assert_eq!(time.delta(), Duration::from_secs(1));
assert_eq!(time.elapsed(), Duration::from_secs(1));
time.update_with_duration(Duration::from_secs(1));
assert_eq!(time.first_update(), Some(startup + Duration::from_secs(1)));
assert_eq!(time.last_update(), Some(startup + Duration::from_secs(3)));
assert_eq!(time.delta(), Duration::from_secs(1));
assert_eq!(time.elapsed(), Duration::from_secs(2));
}
}