Count number of times a repeating Timer wraps around in a tick (#1112)

Added just_finished_count() function

crates/bevy_core/src/time/timer.rs

@@ -13,8 +13,8 @@ pub struct Timer {
     elapsed: f32,
     duration: f32,
     finished: bool,
-    /// Will only be true on the tick `duration` is reached or exceeded.
+    /// Will only be non-zero on the tick `duration` is reached or exceeded.
-    just_finished: bool,
+    just_finished_count: u32,
     paused: bool,
     repeating: bool,
 }
@@ -51,7 +51,8 @@ impl Timer {
         self.paused
     }
 
-    /// Returns the time elapsed on the timer. Guaranteed to be between 0.0 and `duration`, inclusive.
+    /// Returns the time elapsed on the timer. Guaranteed to be between 0.0 and `duration`.
+    /// Will only equal `duration` when the timer is finished and non repeating.
     #[inline]
     pub fn elapsed(&self) -> f32 {
         self.elapsed
@@ -74,8 +75,9 @@ impl Timer {
 
     /// Returns the finished state of the timer.
     ///
-    /// Non repeating timers will stop tracking and stay in the finished state until reset.
+    /// Non-repeating timers will stop tracking and stay in the finished state until reset.
-    /// Repeating timers will only be in the finished state on each tick `duration` is reached or exceeded, and can still be reset at any given point.
+    /// Repeating timers will only be in the finished state on each tick `duration` is reached or exceeded, so in that case
+    /// this function is equivalent to `just_finished`.
     #[inline]
     pub fn finished(&self) -> bool {
         self.finished
@@ -84,7 +86,16 @@ impl Timer {
     /// Will only be true on the tick the timer's duration is reached or exceeded.
     #[inline]
     pub fn just_finished(&self) -> bool {
-        self.just_finished
+        self.just_finished_count > 0
+    }
+
+    /// Returns the total number of times the timer finished during this tick.
+    ///
+    /// This value can be used to ensure no completions of a repeating timer are skipped over due to a tick with an unexpectedly
+    /// long delta time. For non repeating timers, the value will only ever be 0 or 1.
+    #[inline]
+    pub fn just_finished_count(&self) -> u32 {
+        self.just_finished_count
     }
 
     #[inline]
@@ -92,8 +103,11 @@ impl Timer {
         self.repeating
     }
 
-    #[inline]
     pub fn set_repeating(&mut self, repeating: bool) {
+        if !self.repeating && repeating && self.finished {
+            self.elapsed = 0.0;
+            self.finished = self.just_finished();
+        }
         self.repeating = repeating
     }
 
@@ -102,20 +116,24 @@ impl Timer {
         if self.paused {
             return self;
         }
+
         let prev_finished = self.finished;
         self.elapsed += delta;
-
         self.finished = self.elapsed >= self.duration;
-        self.just_finished = !prev_finished && self.finished;
 
         if self.finished {
             if self.repeating {
+                // Count the number of times the timer will wrap around from this tick
+                self.just_finished_count = (self.elapsed / self.duration) as u32;
                 // Repeating timers wrap around
                 self.elapsed %= self.duration;
             } else {
+                self.just_finished_count = if prev_finished { 0 } else { 1 };
                 // Non-repeating timers clamp to duration
                 self.elapsed = self.duration;
             }
+        } else {
+            self.just_finished_count = 0;
         }
         self
     }
@@ -123,7 +141,7 @@ impl Timer {
     #[inline]
     pub fn reset(&mut self) {
         self.finished = false;
-        self.just_finished = false;
+        self.just_finished_count = 0;
         self.elapsed = 0.0;
     }
 
@@ -151,6 +169,7 @@ mod tests {
         assert_eq!(t.duration(), 10.0);
         assert_eq!(t.finished(), false);
         assert_eq!(t.just_finished(), false);
+        assert_eq!(t.just_finished_count(), 0);
         assert_eq!(t.repeating(), false);
         assert_eq!(t.percent(), 0.025);
         assert_eq!(t.percent_left(), 0.975);
@@ -161,6 +180,7 @@ mod tests {
         assert_eq!(t.duration(), 10.0);
         assert_eq!(t.finished(), false);
         assert_eq!(t.just_finished(), false);
+        assert_eq!(t.just_finished_count(), 0);
         assert_eq!(t.repeating(), false);
         assert_eq!(t.percent(), 0.025);
         assert_eq!(t.percent_left(), 0.975);
@@ -170,6 +190,7 @@ mod tests {
         assert_eq!(t.elapsed(), 10.0);
         assert_eq!(t.finished(), true);
         assert_eq!(t.just_finished(), true);
+        assert_eq!(t.just_finished_count(), 1);
         assert_eq!(t.percent(), 1.0);
         assert_eq!(t.percent_left(), 0.0);
         // Continuing to tick when finished should only change just_finished
@@ -177,6 +198,7 @@ mod tests {
         assert_eq!(t.elapsed(), 10.0);
         assert_eq!(t.finished(), true);
         assert_eq!(t.just_finished(), false);
+        assert_eq!(t.just_finished_count(), 0);
         assert_eq!(t.percent(), 1.0);
         assert_eq!(t.percent_left(), 0.0);
     }
@@ -190,14 +212,16 @@ mod tests {
         assert_eq!(t.duration(), 2.0);
         assert_eq!(t.finished(), false);
         assert_eq!(t.just_finished(), false);
+        assert_eq!(t.just_finished_count(), 0);
         assert_eq!(t.repeating(), true);
         assert_eq!(t.percent(), 0.375);
         assert_eq!(t.percent_left(), 0.625);
         // Tick past the end and make sure elapsed wraps
-        t.tick(1.5);
+        t.tick(3.5);
         assert_eq!(t.elapsed(), 0.25);
         assert_eq!(t.finished(), true);
         assert_eq!(t.just_finished(), true);
+        assert_eq!(t.just_finished_count(), 2);
         assert_eq!(t.percent(), 0.125);
         assert_eq!(t.percent_left(), 0.875);
         // Continuing to tick should turn off both finished & just_finished for repeating timers
@@ -205,6 +229,7 @@ mod tests {
         assert_eq!(t.elapsed(), 1.25);
         assert_eq!(t.finished(), false);
         assert_eq!(t.just_finished(), false);
+        assert_eq!(t.just_finished_count(), 0);
         assert_eq!(t.percent(), 0.625);
         assert_eq!(t.percent_left(), 0.375);
     }