src/fighter/attack/mod.rs

@@ -52,7 +52,8 @@ pub enum HitReactionKind {
 pub struct FighterHitReaction {
     pub launch_velocity: FGi32,
     pub launch_angle: FGi32,
-    pub hitstop_frames: HitStop,
+    pub victim_hitstop_frames: HitStop,
+    pub attacker_hitstop_frames: HitStop,
     pub hitstun_frames: u32,
     pub kind: HitReactionKind,
     pub damage: FighterDamage,

src/fighter/attack/reaction.rs

@@ -25,6 +25,7 @@ pub fn resolve_fighter_hits(
         &Player,
         &mut FighterHitstop,
         &mut FighterHitstopShake,
+        &FighterTranslation,
     )>,
     mut receiver: Query<(
         &mut FighterDamage,
@@ -33,6 +34,7 @@ pub fn resolve_fighter_hits(
         &FighterState,
         &FighterInvulnerabilityState,
         &FighterSurfaceState,
+        &FighterTranslation,
     )>,
     attack_scripts: Res<Assets<FighterAttackScript>>,
     game_settings: Res<GameSettings>,
@@ -55,6 +57,7 @@ pub fn resolve_fighter_hits(
             receiver_state,
             invuln_state,
             receiver_surface_state,
+            receiver_translation,
         )) = receiver.get_mut(defender)
         else {
             hit_offset = next_defender;
@@ -64,7 +67,7 @@ pub fn resolve_fighter_hits(
         let damage_data = hits[hit_offset..next_defender]
             .iter()
             .filter_map(|hit| {
-                let Ok((stale_move_queue, facing_dir, _, player, _, _)) =
+                let Ok((stale_move_queue, facing_dir, _, player, _, _, attacker_translation)) =
                     attacker.get(hit.attacker)
                 else {
                     return None;
@@ -74,12 +77,13 @@ pub fn resolve_fighter_hits(
                 let damage_received = stale_move_queue
                     .get_attack_damage_multiplier(hit.attack_kind)
                     * hitbox.damage.0;
+                let angle_flip = receiver_translation.0.x <= attacker_translation.0.x;
                 Some((
                     hit.attacker,
                     damage_received,
                     hitbox,
-                    matches!(facing_dir, FighterFacingDirection::Left),
                     player.handle,
+                    angle_flip,
                 ))
             })
             .collect::<Vec<_>>();
@@ -93,28 +97,35 @@ pub fn resolve_fighter_hits(
             .ok_or(FighterErrors::FighterManifestNotFound)?;
         let mut reactions = Vec::with_capacity(damage_data.len());
 
-        for (attacker_entity, attack_damage, hitbox, facing_left, attacker_slot) in damage_data {
+        let crouch_canceling = if let FighterState::Crouch(crouch_state) = &receiver_state {
+            crouch_state.is_crouch_cancelling()
+        } else {
+            false
+        };
+
+        for (attacker_entity, attack_damage, hitbox, attacker_slot, angle_flip) in damage_data {
             let knockback = hitbox.calculate_knockback(
                 &fighter_manifest.attributes,
                 *receiver_damage,
                 FighterDamage(total_damage_received_this_frame),
                 false,
-                false,
+                crouch_canceling,
             );
-            let angle = hitbox.angle.get_angle(
+            let launch_angle = hitbox.angle.get_angle(
                 &knockback,
                 receiver_surface_state.is_grounded(),
                 &game_settings,
             );
-            dbg!(knockback, angle);
+
-            let launch_angle = if facing_left {
+            let launch_angle = if angle_flip {
-                FGi32::lit("180.0") - angle
+                FGi32::lit("180.0") - launch_angle
             } else {
-                angle
+                launch_angle
             };
 
             // Attacker hitstop and data
-            let hitstop = HitStop::calculate(FighterDamage(attack_damage), matches!(receiver_state, FighterState::Crouch(..)));
+            let victim_hitstop_frames = HitStop::calculate(FighterDamage(attack_damage), crouch_canceling);
+            let attacker_hitstop_frames = HitStop::calculate(FighterDamage(attack_damage), false);
             reactions.push((
                 attacker_entity,
                 attacker_slot,
@@ -122,7 +133,8 @@ pub fn resolve_fighter_hits(
                     launch_velocity: knockback.get_launch_speed(&game_settings),
                     launch_angle,
                     hitstun_frames: knockback.get_hitstun_frames(&game_settings),
-                    hitstop_frames: hitstop,
+                    victim_hitstop_frames,
+                    attacker_hitstop_frames,
                     kind: HitReactionKind::Flinch,
                     damage: FighterDamage(attack_damage),
                 },
@@ -137,20 +149,20 @@ pub fn resolve_fighter_hits(
         }
 
         for (attacker_entity, _, reaction) in &reactions {
-            let Ok((.., _, mut hitstop, mut hitstop_shake)) = attacker.get_mut(*attacker_entity)
+            let Ok((.., _, mut hitstop, mut hitstop_shake, _)) = attacker.get_mut(*attacker_entity)
             else {
                 continue;
             };
 
-            if hitstop.remaining_frames < reaction.hitstop_frames.0 {
+            if hitstop.remaining_frames < reaction.attacker_hitstop_frames.0 {
                 let shake_kind = if receiver_state.is_visually_grounded() {
                     FighterHitstopShakeKind::Horizontal
                 } else {
                     FighterHitstopShakeKind::Vertical
                 };
-                hitstop.remaining_frames = reaction.hitstop_frames.0;
+                hitstop.remaining_frames = reaction.attacker_hitstop_frames.0;
                 let shake_frames = reaction
-                    .hitstop_frames
+                    .attacker_hitstop_frames
                     .calculate_shake_frames(&game_settings);
                 hitstop_shake.total_frames = shake_frames;
                 hitstop_shake.remaining_frames = shake_frames;

src/fighter/state/crouch.rs

@@ -148,6 +148,15 @@ impl FighterStateImpl for CrouchState {
     }
 }
 
+impl CrouchState {
+    pub fn is_crouch_cancelling(&self) -> bool {
+        match self.sub_state {
+            CrouchSubState::Entering { .. } | CrouchSubState::Idle => true,
+            CrouchSubState::Exiting => false,
+        }
+    }
+}
+
 pub fn check_input(state_context: &InterruptContext) -> Option<FighterState> {
     let input_frame = state_context.input.get_last_frame();
 

src/fighter/state/mod.rs

@@ -494,9 +494,9 @@ pub fn state_interrupt_system(
             .expect("Fighter manifest should be valid");
 
         let new_state = if let Some(reaction) = pending_hit_reaction.take() {
-            hitstop.remaining_frames = *reaction.hitstop_frames;
+            hitstop.remaining_frames = *reaction.victim_hitstop_frames;
             let shake_frames = reaction
-                .hitstop_frames
+                .victim_hitstop_frames
                 .calculate_shake_frames(&game_settings);
             hitstop_shake.role = FighterHitstopShakeRole::Receiver;
             hitstop_shake.total_frames = shake_frames;
@@ -515,7 +515,7 @@ pub fn state_interrupt_system(
 
             if let hitstun::HitstopStateKind::Grounded = hitstop_kind {
                 let straight_up_angle = FGi32::lit("90.0");
-                if reaction.hitstop_frames
+                if reaction.victim_hitstop_frames
                     >= HitStop::new(game_settings.fighter_common.tumble_bounce_hitstop_threshold)
                 {
                     hitstop_kind = hitstun::HitstopStateKind::Airborne;

src/scripting/move_compiler.rs

@@ -260,9 +260,8 @@ pub fn compile_script(text: &str) -> Result<FighterAttackScript, String> {
             );
         }
 
-        // Keep the original script syntax working. A hitbox without an
+        // Keep the original script syntax working. Melee's default collision
-        // explicit group behaves as its own group, which preserves the old
+        // group is shared by all hitbox slots in an attack.
-        // one-hit-per-target behavior.
         {
             let mc = mc.clone();
             engine.register_fn(
@@ -280,7 +279,7 @@ pub fn compile_script(text: &str) -> Result<FighterAttackScript, String> {
                     add_hitbox(
                         &mc,
                         id,
-                        id,
+                        0,
                         bone,
                         damage,
                         offset,
@@ -461,4 +460,19 @@ mod tests {
         assert_eq!(script.hitboxes[0].id, 7);
         assert_eq!(script.hitboxes[0].group, 3);
     }
+
+    #[test]
+    fn legacy_hitboxes_share_the_default_collision_group() {
+        let script = compile_script(
+            r#"
+                frame(1);
+                hitbox(0, "hand_l", damage("1"), vec3("0", "0", "0"), fg32("1"), angle("0"), knockback_normal(), knockback("1"), fg32("1"));
+                hitbox(1, "hand_l", damage("1"), vec3("0", "0", "0"), fg32("1"), angle("0"), knockback_normal(), knockback("1"), fg32("1"));
+                frame(2);
+            "#,
+        )
+        .unwrap();
+
+        assert_eq!(script.hitboxes.iter().map(|hitbox| hitbox.group).collect::<Vec<_>>(), vec![0, 0]);
+    }
 }