Make a bat flap the sculk sensors while it is awake

Entity.processFlappingMovement emits a flap game event when the entity flaps over air;
Bee and Bat each override isFlapping, a bee every other tick while flying and a bat every
tenth tick while it is not resting. Horizon only modelled the bee, so a bat flying around
was silent to sculk sensors and a warden.

crates/horizon-client/src/game/sculk.rs

@@ -1713,6 +1713,7 @@ impl Game<'_> {
             Option<i64>,
             Option<u32>,
             u32,
+            bool,
         )> = self
             .mobs
             .iter()
@@ -1727,10 +1728,11 @@ impl Game<'_> {
                     m.last_damage.map(|(_, t)| t),
                     m.extra.mount,
                     m.age,
+                    m.species() == Species::Bat && horizon_client::mobs::bat::resting(m),
                 )
             })
             .collect();
-        for (id, at, on_ground, in_water, species, damaged, vehicle, age) in snapshot {
+        for (id, at, on_ground, in_water, species, damaged, vehicle, age, resting) in snapshot {
             if on_ground {
                 self.step_on_redstone_ore(at, false, false);
             }
@@ -1749,10 +1751,10 @@ impl Game<'_> {
                     false,
                     warden,
                 );
-                // Entity.processFlappingMovement with Bee.isFlapping: a bee off
-                // the ground over air flaps on every other tick (the mob's own
-                // `MobEvent::GameEvent` is not read here).
-                if species == Species::Bee && !on_ground && age.is_multiple_of(2) {
+                // Entity.processFlappingMovement: what flaps this move flaps
+                // over air only (the mob's own `MobEvent::GameEvent` is not
+                // read here).
+                if flaps(species, resting, on_ground, age) {
                     let below = self.world.block(
                         at[0].floor() as i32,
                         (at[1] - 1.0e-5).floor() as i32,
@@ -1954,6 +1956,17 @@ pub(super) fn darkness_blend_added(e: &EffectInstance, blend: bool) -> (f32, f32
     (factor, factor)
 }
 
+/// `Entity.processFlappingMovement`'s per-tick gate, before its air-below
+/// test: `Bee.isFlapping` (flying, every other tick) and `Bat.isFlapping`
+/// (awake, every tenth tick).
+fn flaps(species: Species, resting: bool, on_ground: bool, age: u32) -> bool {
+    match species {
+        Species::Bee => !on_ground && age.is_multiple_of(2),
+        Species::Bat => !resting && age.is_multiple_of(10),
+        _ => false,
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -1973,6 +1986,20 @@ mod tests {
         assert_eq!(index.iter().last(), Some(&(41, 4, 0)));
     }
 
+    /// A bat flaps every tenth tick while it is not resting, whether it is on
+    /// the ground or not; a resting bat never flaps and nothing else does.
+    #[test]
+    fn a_bat_flaps_every_tenth_tick_unless_it_is_resting() {
+        assert!(flaps(Species::Bat, false, false, 0));
+        assert!(flaps(Species::Bat, false, true, 10));
+        assert!(!flaps(Species::Bat, false, false, 11));
+        assert!(!flaps(Species::Bat, true, false, 20), "resting");
+        assert!(flaps(Species::Bee, false, false, 4));
+        assert!(!flaps(Species::Bee, false, true, 4), "a bee on the ground");
+        assert!(!flaps(Species::Bat, false, false, 5));
+        assert!(!flaps(Species::Cow, false, false, 0));
+    }
+
     #[test]
     fn centres_and_blocks_agree() {
         assert_eq!(center((1, 2, 3)), [1.5, 2.5, 3.5]);