Unify FixedTime and Time (ver. B) (proof-of-concept)

crates/bevy_diagnostic/src/frame_time_diagnostics_plugin.rs

@@ -2,7 +2,7 @@ use crate::{Diagnostic, DiagnosticId, Diagnostics, RegisterDiagnostic};
 use bevy_app::prelude::*;
 use bevy_core::FrameCount;
 use bevy_ecs::prelude::*;
-use bevy_time::Time;
+use bevy_time::RealTime;
 
 /// Adds "frame time" diagnostic to an App, specifically "frame time", "fps" and "frame count"
 #[derive(Default)]
@@ -30,12 +30,12 @@ impl FrameTimeDiagnosticsPlugin {
 
     pub fn diagnostic_system(
         mut diagnostics: Diagnostics,
-        time: Res<Time>,
+        real_time: Res<RealTime>,
         frame_count: Res<FrameCount>,
     ) {
         diagnostics.add_measurement(Self::FRAME_COUNT, || frame_count.0 as f64);
 
-        let delta_seconds = time.raw_delta_seconds_f64();
+        let delta_seconds = real_time.delta_seconds_f64();
         if delta_seconds == 0.0 {
             return;
         }

crates/bevy_diagnostic/src/log_diagnostics_plugin.rs

@@ -2,7 +2,7 @@ use super::{Diagnostic, DiagnosticId, DiagnosticsStore};
 use bevy_app::prelude::*;
 use bevy_ecs::prelude::*;
 use bevy_log::{debug, info};
-use bevy_time::{Time, Timer, TimerMode};
+use bevy_time::{RealTime, Timer, TimerMode};
 use bevy_utils::Duration;
 
 /// An App Plugin that logs diagnostics to the console
@@ -82,10 +82,10 @@ impl LogDiagnosticsPlugin {
 
     fn log_diagnostics_system(
         mut state: ResMut<LogDiagnosticsState>,
-        time: Res<Time>,
+        real_time: Res<RealTime>,
         diagnostics: Res<DiagnosticsStore>,
     ) {
-        if state.timer.tick(time.raw_delta()).finished() {
+        if state.timer.tick(real_time.delta()).finished() {
             if let Some(ref filter) = state.filter {
                 for diagnostic in filter.iter().flat_map(|id| {
                     diagnostics
@@ -107,10 +107,10 @@ impl LogDiagnosticsPlugin {
 
     fn log_diagnostics_debug_system(
         mut state: ResMut<LogDiagnosticsState>,
-        time: Res<Time>,
+        real_time: Res<RealTime>,
         diagnostics: Res<DiagnosticsStore>,
     ) {
-        if state.timer.tick(time.raw_delta()).finished() {
+        if state.timer.tick(real_time.delta()).finished() {
             if let Some(ref filter) = state.filter {
                 for diagnostic in filter.iter().flat_map(|id| {
                     diagnostics

crates/bevy_gilrs/src/rumble.rs

@@ -5,7 +5,7 @@ use bevy_ecs::{
 };
 use bevy_input::gamepad::{GamepadRumbleIntensity, GamepadRumbleRequest};
 use bevy_log::{debug, warn};
-use bevy_time::Time;
+use bevy_time::RealTime;
 use bevy_utils::{Duration, HashMap};
 use gilrs::{
     ff::{self, BaseEffect, BaseEffectType, Repeat, Replay},
@@ -120,12 +120,12 @@ fn handle_rumble_request(
     Ok(())
 }
 pub(crate) fn play_gilrs_rumble(
-    time: Res<Time>,
+    real_time: Res<RealTime>,
     mut gilrs: NonSendMut<Gilrs>,
     mut requests: EventReader<GamepadRumbleRequest>,
     mut running_rumbles: NonSendMut<RunningRumbleEffects>,
 ) {
-    let current_time = time.raw_elapsed();
+    let current_time = real_time.elapsed();
     // Remove outdated rumble effects.
     for rumbles in running_rumbles.rumbles.values_mut() {
         // `ff::Effect` uses RAII, dropping = deactivating

crates/bevy_time/src/clock.rs

@@ -0,0 +1,183 @@
+use bevy_reflect::{FromReflect, Reflect};
+use bevy_utils::{default, Duration, Instant};
+
+fn duration_div_rem(dividend: Duration, divisor: Duration) -> (u32, Duration) {
+    // `Duration` does not have a built-in modulo operation
+    let quotient = (dividend.as_nanos() / divisor.as_nanos()) as u32;
+    let remainder = dividend - (quotient * divisor);
+    (quotient, remainder)
+}
+
+/// A stopwatch that tracks the time since last update and the time since creation.
+#[derive(Debug, Clone, Copy, Reflect, FromReflect, PartialEq)]
+pub struct Clock {
+    startup: Instant,
+    first_update: Option<Instant>,
+    last_update: Option<Instant>,
+    delta: Duration,
+    delta_seconds: f32,
+    delta_seconds_f64: f64,
+    elapsed: Duration,
+    elapsed_seconds: f32,
+    elapsed_seconds_f64: f64,
+    wrap_period: Duration,
+    elapsed_wrapped: Duration,
+    elapsed_seconds_wrapped: f32,
+    elapsed_seconds_wrapped_f64: f64,
+}
+
+impl Default for Clock {
+    fn default() -> Self {
+        Self {
+            startup: Instant::now(),
+            first_update: None,
+            last_update: None,
+            delta: Duration::ZERO,
+            delta_seconds: 0.0,
+            delta_seconds_f64: 0.0,
+            elapsed: Duration::ZERO,
+            elapsed_seconds: 0.0,
+            elapsed_seconds_f64: 0.0,
+            wrap_period: Duration::from_secs(3600), // 1 hour
+            elapsed_wrapped: Duration::ZERO,
+            elapsed_seconds_wrapped: 0.0,
+            elapsed_seconds_wrapped_f64: 0.0,
+        }
+    }
+}
+
+impl Clock {
+    /// Constructs a new `Clock` instance with a specific startup `Instant`.
+    pub fn new(startup: Instant) -> Self {
+        Self {
+            startup,
+            ..default()
+        }
+    }
+
+    /// Advances the clock by `dt` and records it happening at `instant`.
+    pub fn update(&mut self, dt: Duration, instant: Instant) {
+        self.delta = dt;
+        self.delta_seconds = self.delta.as_secs_f32();
+        self.delta_seconds_f64 = self.delta.as_secs_f64();
+
+        self.elapsed += dt;
+        self.elapsed_seconds = self.elapsed.as_secs_f32();
+        self.elapsed_seconds_f64 = self.elapsed.as_secs_f64();
+
+        self.elapsed_wrapped = duration_div_rem(self.elapsed, self.wrap_period).1;
+        self.elapsed_seconds_wrapped = self.elapsed_wrapped.as_secs_f32();
+        self.elapsed_seconds_wrapped_f64 = self.elapsed_wrapped.as_secs_f64();
+
+        if self.last_update.is_none() {
+            self.first_update = Some(instant);
+        }
+
+        self.last_update = Some(instant);
+    }
+
+    /// Returns the [`Instant`] the clock was created.
+    #[inline]
+    pub fn startup(&self) -> Instant {
+        self.startup
+    }
+
+    /// Returns the [`Instant`] when [`update`](#method.update) was first called, if it exists.
+    #[inline]
+    pub fn first_update(&self) -> Option<Instant> {
+        self.first_update
+    }
+
+    /// Returns the [`Instant`] when [`update`](#method.update) was last called, if it exists.
+    #[inline]
+    pub fn last_update(&self) -> Option<Instant> {
+        self.last_update
+    }
+
+    /// Returns how much time has advanced since the last [`update`](#method.update), as a [`Duration`].
+    #[inline]
+    pub fn delta(&self) -> Duration {
+        self.delta
+    }
+
+    /// Returns how much time has advanced since the last [`update`](#method.update), as [`f32`] seconds.
+    #[inline]
+    pub fn delta_seconds(&self) -> f32 {
+        self.delta_seconds
+    }
+
+    /// Returns how much time has advanced since the last [`update`](#method.update), as [`f64`] seconds.
+    #[inline]
+    pub fn delta_seconds_f64(&self) -> f64 {
+        self.delta_seconds_f64
+    }
+
+    /// Returns how much time has advanced since [`startup`](#method.startup), as [`Duration`].
+    #[inline]
+    pub fn elapsed(&self) -> Duration {
+        self.elapsed
+    }
+
+    /// Returns how much time has advanced since [`startup`](#method.startup), as [`f32`] seconds.
+    ///
+    /// **Note:** This is a monotonically increasing value. It's precision will degrade over time.
+    /// If you need an `f32` but that precision loss is unacceptable,
+    /// use [`elapsed_seconds_wrapped`](#method.elapsed_seconds_wrapped).
+    #[inline]
+    pub fn elapsed_seconds(&self) -> f32 {
+        self.elapsed_seconds
+    }
+
+    /// Returns how much time has advanced since [`startup`](#method.startup), as [`f64`] seconds.
+    #[inline]
+    pub fn elapsed_seconds_f64(&self) -> f64 {
+        self.elapsed_seconds_f64
+    }
+
+    /// Returns how much time has advanced since [`startup`](#method.startup) modulo
+    /// the [`wrap_period`](#method.wrap_period), as [`Duration`].
+    #[inline]
+    pub fn elapsed_wrapped(&self) -> Duration {
+        self.elapsed_wrapped
+    }
+
+    /// Returns how much time has advanced since [`startup`](#method.startup) modulo
+    /// the [`wrap_period`](#method.wrap_period), as [`f32`] seconds.
+    ///
+    /// This method is intended for applications (e.g. shaders) that require an [`f32`] value but
+    /// suffer from the gradual precision loss of [`elapsed_seconds`](#method.elapsed_seconds).
+    #[inline]
+    pub fn elapsed_seconds_wrapped(&self) -> f32 {
+        self.elapsed_seconds_wrapped
+    }
+
+    /// Returns how much time has advanced since [`startup`](#method.startup) modulo
+    /// the [`wrap_period`](#method.wrap_period), as [`f64`] seconds.
+    #[inline]
+    pub fn elapsed_seconds_wrapped_f64(&self) -> f64 {
+        self.elapsed_seconds_wrapped_f64
+    }
+
+    /// Returns the modulus used to calculate [`elapsed_wrapped`](#method.elapsed_wrapped) and
+    /// [`elapsed_wrapped`](#method.elapsed_wrapped).
+    ///
+    /// **Note:** The default modulus is one hour.
+    #[inline]
+    pub fn wrap_period(&self) -> Duration {
+        self.wrap_period
+    }
+
+    /// Sets the modulus used to calculate [`elapsed_wrapped`](#method.elapsed_wrapped) and
+    /// [`elapsed_wrapped`](#method.elapsed_wrapped).
+    ///
+    /// **Note:** This will not take effect until the next update.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `wrap_period` is a zero-length duration.
+    #[inline]
+    pub fn set_wrap_period(&mut self, wrap_period: Duration) {
+        assert!(!wrap_period.is_zero(), "division by zero");
+        self.wrap_period = wrap_period;
+    }
+}

crates/bevy_time/src/common_conditions.rs

@@ -1,12 +1,10 @@
-use crate::{fixed_timestep::FixedTime, Time, Timer, TimerMode};
+use crate::{Time, Timer, TimerMode};
 use bevy_ecs::system::Res;
 use bevy_utils::Duration;
 
 /// Run condition that is active on a regular time interval, using [`Time`] to advance
 /// the timer.
 ///
-/// If used for a fixed timestep system, use [`on_fixed_timer`] instead.
-///
 /// ```rust,no_run
 /// # use bevy_app::{App, NoopPluginGroup as DefaultPlugins, PluginGroup, Update};
 /// # use bevy_ecs::schedule::IntoSystemConfigs;
@@ -29,9 +27,8 @@ use bevy_utils::Duration;
 /// times. This condition should only be used with large time durations (relative to
 /// delta time).
 ///
-/// For more accurate timers, use the [`Timer`] class directly (see
-/// [`Timer::times_finished_this_tick`] to address the problem mentioned above), or
-/// use fixed timesteps that allow systems to run multiple times per frame.
+/// To create a more precise timer, use the [`Timer`] class directly (see
+/// [`Timer::times_finished_this_tick`], which can address the issue described above).
 pub fn on_timer(duration: Duration) -> impl FnMut(Res<Time>) -> bool + Clone {
     let mut timer = Timer::new(duration, TimerMode::Repeating);
     move |time: Res<Time>| {
@@ -40,40 +37,6 @@ pub fn on_timer(duration: Duration) -> impl FnMut(Res<Time>) -> bool + Clone {
     }
 }
 
-/// Run condition that is active on a regular time interval, using [`FixedTime`] to
-/// advance the timer.
-///
-/// If used for a non-fixed timestep system, use [`on_timer`] instead.
-///
-/// ```rust,no_run
-/// # use bevy_app::{App, NoopPluginGroup as DefaultPlugins, PluginGroup, FixedUpdate};
-/// # use bevy_ecs::schedule::IntoSystemConfigs;
-/// # use bevy_utils::Duration;
-/// # use bevy_time::common_conditions::on_fixed_timer;
-/// fn main() {
-///     App::new()
-///         .add_plugins(DefaultPlugins)
-///         .add_systems(FixedUpdate,
-///             tick.run_if(on_fixed_timer(Duration::from_secs(1))),
-///         )
-///         .run();
-/// }
-/// fn tick() {
-///     // ran once a second
-/// }
-/// ```
-///
-/// Note that this run condition may not behave as expected if `duration` is smaller
-/// than the fixed timestep period, since the timer may complete multiple times in
-/// one fixed update.
-pub fn on_fixed_timer(duration: Duration) -> impl FnMut(Res<FixedTime>) -> bool + Clone {
-    let mut timer = Timer::new(duration, TimerMode::Repeating);
-    move |time: Res<FixedTime>| {
-        timer.tick(time.period);
-        timer.just_finished()
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -85,9 +48,7 @@ mod tests {
     #[test]
     fn distributive_run_if_compiles() {
         Schedule::default().add_systems(
-            (test_system, test_system)
-                .distributive_run_if(on_timer(Duration::new(1, 0)))
-                .distributive_run_if(on_fixed_timer(Duration::new(1, 0))),
+            (test_system, test_system).distributive_run_if(on_timer(Duration::new(1, 0))),
         );
     }
 }