src/fighter/animation.rs

@@ -100,4 +100,5 @@ pub enum AnimKind {
     AttackDownTilt,
     AttackNeutralAir,
     AttackForwardAir,
+    AttackDash,
 }

src/fighter/attack/mod.rs

@@ -221,6 +221,7 @@ pub enum AttackKind {
     UpSmash,
     DownSmash,
     ForwardSmash,
+    DashAttack,
 }
 
 impl AttackKind {
@@ -238,6 +239,7 @@ impl AttackKind {
             AttackKind::UpSmash => AnimKind::AttackUpTilt,
             AttackKind::DownSmash => AnimKind::AttackUpTilt,
             AttackKind::ForwardSmash => AnimKind::AttackUpTilt,
+            AttackKind::DashAttack => AnimKind::AttackDash,
         }
     }
 }

src/fighter/baked_animation/mod.rs

@@ -364,6 +364,38 @@ mod tests {
         assert_eq!(matrices.root_motion_delta(), FGVec3::lit("4", "0", "0"));
     }
 
+    #[test]
+    fn root_motion_translation_is_removed_from_published_pose() {
+        let names = ["root".into(), "hand".into()];
+        let parents = [None, Some(0)];
+        let mut root = FixedMat4::IDENTITY;
+        root.translate(FGVec3::lit("3", "4", "5"));
+        let mut hand = FixedMat4::IDENTITY;
+        hand.translate(FGVec3::lit("1", "2", "0"));
+        let mut matrices = FighterBoneMatrices::default();
+        let frame = crate::fighter::animation::FighterAnimationFrame::new(AnimKind::Wait, false);
+
+        matrices.set_pose_with_frame(
+            frame,
+            "root",
+            FGVec3::ZERO,
+            None,
+            AnimKind::Wait,
+            &names,
+            &parents,
+            &[root, hand],
+            FGi32::ONE,
+        );
+
+        assert_eq!(matrices.root_motion_delta(), FGVec3::ZERO);
+        assert_eq!(matrices.local(0).unwrap().get_translation(), FGVec3::ZERO);
+        assert_eq!(matrices.get_current("root").unwrap().get_translation(), FGVec3::ZERO);
+        assert_eq!(
+            matrices.get_current("hand").unwrap().get_translation(),
+            FGVec3::lit("1", "2", "0")
+        );
+    }
+
     #[test]
     fn repeating_root_motion_preserves_cycle_displacement_at_wrap() {
         let names = ["root".into()];

src/fighter/baked_animation/runtime.rs

@@ -122,6 +122,10 @@ pub struct FighterBoneMatrices {
     model_matrices: Vec<Option<FixedMat4>>,
     presentation_kind: Option<AnimKind>,
     previous_animation_frame: Option<FighterAnimationFrame>,
+    /// The raw, scaled model-space root translation used as the baseline for
+    /// root-motion extraction.  This is kept separately because the published
+    /// pose has the root translation removed.
+    previous_root_motion_translation: Option<FGVec3>,
     root_motion_delta: crate::math::vec3::FGVec3,
 }
 
@@ -351,6 +355,17 @@ impl FighterBoneMatrices {
         }
         self.local_matrices.clear();
         self.local_matrices.extend_from_slice(local);
+
+        let root_index = if root_motion_bone.is_empty() {
+            None
+        } else {
+            Some(
+                self.bone_names
+                    .iter()
+                    .position(|name| name == root_motion_bone)
+                    .expect("configured root motion bone should exist"),
+            )
+        };
         self.model_matrices.resize(local.len(), None);
         self.model_matrices.fill(None);
         for index in 0..local.len() {
@@ -365,6 +380,26 @@ impl FighterBoneMatrices {
                 [FGi32::ZERO, FGi32::ZERO, FGi32::ZERO, FGi32::ONE],
             ],
         };
+        let raw_root_motion_translation = root_index.map(|root_index| {
+            model_scale
+                .mul(
+                    self.model_matrices[root_index]
+                        .expect("baked bone hierarchy should be valid"),
+                )
+                .get_translation()
+        });
+
+        // Gameplay owns the root's displacement.  Keep rotation and scale in
+        // the animation, but remove its translation before publishing the pose
+        // used by visuals and gameplay volumes.
+        if let Some(root_index) = root_index {
+            self.local_matrices[root_index].translate(FGVec3::ZERO);
+            self.model_matrices.fill(None);
+            for index in 0..local.len() {
+                resolve_model_transform(index, parents, &self.local_matrices, &mut self.model_matrices)
+                    .expect("baked bone hierarchy should be valid");
+            }
+        }
         self.matrices.clear();
         self.matrices.extend(
             self.model_matrices.iter().map(|matrix| {
@@ -374,15 +409,12 @@ impl FighterBoneMatrices {
         self.root_motion_delta = if advance_history
             && !animation_changed
             && self.previous_animation_frame.is_some()
-            && !root_motion_bone.is_empty()
+            && let (Some(current), Some(previous)) = (
+                raw_root_motion_translation,
+                self.previous_root_motion_translation,
+            )
         {
-            let root_index = self
-                .bone_names
-                .iter()
-                .position(|name| name == root_motion_bone)
-                .expect("configured root motion bone should exist");
-            let mut delta = self.matrices[root_index].get_translation()
-                - self.previous_frame_matrices[root_index].get_translation();
+            let mut delta = current - previous;
             if animation_frame.repeat
                 && self.previous_animation_frame.is_some_and(|previous| {
                     previous.frame.saturating_add(1) == animation_frame.frame
@@ -395,6 +427,7 @@ impl FighterBoneMatrices {
         } else {
             FGVec3::ZERO
         };
+        self.previous_root_motion_translation = raw_root_motion_translation;
         if advance_history {
             self.previous_animation_frame = Some(animation_frame);
         }

src/fighter/state/dash.rs

@@ -4,7 +4,7 @@ use super::{
 };
 use crate::fighter::FighterFacingDirection;
 use crate::fighter::animation::AnimKind;
-use crate::fighter::state::FighterState;
+use crate::fighter::state::{FighterState, ground_attack};
 use crate::input::FighterCommands::{SmashMoveLeft, SmashMoveRight};
 
 #[derive(Debug, Clone, Hash)]
@@ -23,6 +23,16 @@ impl FighterStateImpl for DashState {
     fn check_interrupt(&self, ctx: &mut InterruptContext) -> Option<FighterState> {
         let attributes = ctx.fighter_attributes;
 
+        if ctx.get_current_animation_frame() <= 2 {
+            if let Some(state) = ground_attack::check_interrupt(ctx) {
+                return Some(state);
+            }
+        } else {
+            if let Some(state) = ground_attack::check_interrupt_dash_attack(ctx) {
+                return Some(state);
+            }
+        }
+
         // A reverse dash can interrupt before IASA
         if let Some(direction) =
             check_smash_input_with_dir(ctx).filter(|direction| *direction != self.direction)

src/fighter/state/ground_attack.rs

@@ -1,14 +1,20 @@
-use crate::fighter::{
-    attack::{AttackKind, update_active_attack},
+use bevy::{asset::Assets, log::error};
+
+use crate::{
+    fighter::{
+        attack::{AttackKind, FighterAttackScriptAssets, update_active_attack},
         state::{
             CollisionContext, EnterContext, ExitContext, FighterState, FighterStateImpl,
-        InterruptContext, UpdateContext, wait::WaitState,
+            InterruptContext, UpdateContext, ground, wait::WaitState,
         },
+    },
+    scripting::FighterAttackScript,
 };
 
 #[derive(Clone, Debug, Hash)]
 pub struct GroundAttackState {
     pub attack_kind: AttackKind,
+    pub use_root_motion: bool,
 }
 
 impl FighterStateImpl for GroundAttackState {
@@ -37,6 +43,18 @@ impl FighterStateImpl for GroundAttackState {
                     .expect("ground attack must have active hitboxes"),
                 animation_frame,
             );
+
+            // root motion
+            if script.use_root_motion {
+                state_context.velocity.0.x = state_context.animation_root_motion_delta.x;
+                ground::apply_grounded_motion(
+                    state_context.velocity,
+                    state_context.translation,
+                    state_context.prev_translation,
+                );
+            } else {
+                ground::update_friction_motion(state_context);
+            }
         }
     }
 
@@ -48,7 +66,7 @@ impl FighterStateImpl for GroundAttackState {
         let script = state_context.attack_script_assets.scripts[&self.attack_kind].clone();
         state_context.hitboxes.0 = Some(crate::fighter::FighterActiveAttack {
             kind: self.attack_kind,
-            script,
+            script: script.clone(),
             active_hitboxes: Vec::new(),
             solved_hitboxes: Vec::new(),
             hit_groups: Vec::new(),
@@ -62,9 +80,9 @@ impl FighterStateImpl for GroundAttackState {
 
     fn check_collision_interrupt(
         &mut self,
-        _state_context: &mut CollisionContext,
+        state_context: &mut CollisionContext,
     ) -> Option<FighterState> {
-        None
+        ground::collision_interrupt(state_context, !self.use_root_motion)
     }
 
     fn is_visually_grounded<'a>(&'a self) -> bool {
@@ -72,6 +90,51 @@ impl FighterStateImpl for GroundAttackState {
     }
 }
 
+impl GroundAttackState {
+    fn create(
+        attack_kind: AttackKind,
+        attack_script_assets: &FighterAttackScriptAssets,
+        attack_scripts: &Assets<FighterAttackScript>,
+    ) -> Result<Self, AirAttackStateCreateError> {
+        let asset_script = attack_script_assets.scripts.get(&attack_kind).ok_or(
+            AirAttackStateCreateError::AttackScriptAssetNotFound {
+                attack: attack_kind,
+            },
+        )?;
+
+        let script = attack_scripts.get(asset_script).ok_or(
+            AirAttackStateCreateError::AttackScriptNotFound {
+                attack: attack_kind,
+            },
+        )?;
+
+        Ok(Self {
+            attack_kind,
+            use_root_motion: script.use_root_motion
+        })
+    }
+}
+
+#[derive(thiserror::Error, Debug)]
+pub enum AirAttackStateCreateError {
+    #[error("Attack script: {attack:?} not found")]
+    AttackScriptNotFound { attack: AttackKind },
+    #[error("Attack script asset: {attack:?} not found")]
+    AttackScriptAssetNotFound { attack: AttackKind },
+}
+
+pub fn check_interrupt_shared(state_context: &InterruptContext, attack_kind: AttackKind) -> Option<FighterState> {
+    let state = GroundAttackState::create(attack_kind, state_context.attack_script_assets, state_context.attack_scripts);
+
+    match state {
+        Ok(state) => Some(FighterState::GroundAttack(state)),
+        Err(create_error) => {
+            error!("{}", create_error);
+            None
+        },
+    }
+}
+
 pub fn check_interrupt(state_context: &InterruptContext) -> Option<FighterState> {
     if state_context
         .input
@@ -81,9 +144,18 @@ pub fn check_interrupt(state_context: &InterruptContext) -> Option<FighterState>
             .input
             .get_attack_command_type()
             .to_attack_kind_grounded();
-        Some(FighterState::GroundAttack(GroundAttackState {
-            attack_kind,
-        }))
+        check_interrupt_shared(state_context, attack_kind)
+    } else {
+        None
+    }
+}
+
+pub fn check_interrupt_dash_attack(state_context: &InterruptContext) -> Option<FighterState> {
+    if state_context
+        .input
+        .has_command(crate::input::FighterCommands::Attack)
+    {
+        check_interrupt_shared(state_context, AttackKind::DashAttack)
     } else {
         None
     }

src/fighter/state/mod.rs

@@ -11,7 +11,7 @@ use crate::fighter::attack::{
     FighterStaleMoveQueue, HitStop,
 };
 use crate::fighter::attributes::FighterAttributes;
-use crate::fighter::baked_animation::BakedFighterAnimations;
+use crate::fighter::baked_animation::{BakedFighterAnimations, FighterBoneMatrices};
 use crate::fighter::ecb::FighterPreviousECB;
 use crate::fighter::manifest::FighterManifest;
 use crate::fighter::state::hitstun::HitstunState;
@@ -29,6 +29,7 @@ use crate::match_loading::MatchConfig;
 use crate::match_runtime::MatchState;
 use crate::math::int::FGi32;
 use crate::math::vec::FGVec2;
+use crate::math::vec3::FGVec3;
 use crate::player::Player;
 use crate::scripting::FighterAttackScript;
 use crate::stage::line::StageCollision;
@@ -191,6 +192,9 @@ pub struct UpdateContext<'a> {
     pub knockback_velocity: &'a mut FighterKnockbackVelocity,
     pub vulnerability: &'a mut FighterInvulnerabilityState,
     pub game_settings: &'a GameSettings,
+    /// Root motion in the fighter's gameplay plane: X is world-right and Y is
+    /// world-up. Animation +Z is forward and is mirrored by facing direction.
+    pub animation_root_motion_delta: FGVec2,
     pub animation_frame: u32,
     pub fighter_attributes: &'a FighterAttributes,
     pub attack_scripts: &'a Assets<FighterAttackScript>,
@@ -198,6 +202,13 @@ pub struct UpdateContext<'a> {
     pub facing_direction: &'a FighterFacingDirection,
 }
 
+fn animation_root_motion_to_gameplay(
+    delta: FGVec3,
+    facing_direction: &FighterFacingDirection,
+) -> FGVec2 {
+    FGVec2::new(delta.z * facing_direction.to_sign(), delta.y)
+}
+
 impl UpdateContext<'_> {
     pub fn get_current_animation_frame(&self) -> u32 {
         self.animation_frame
@@ -275,6 +286,7 @@ pub struct FighterFrameQuery {
     pub animation_frame: &'static mut FighterAnimationFrame,
     pub vulnerability: &'static mut FighterInvulnerabilityState,
     pub fighter: &'static Fighter,
+    pub bone_matrices: &'static FighterBoneMatrices,
 }
 
 impl<'w, 's> FighterFrameQueryItem<'w, 's> {
@@ -365,6 +377,10 @@ impl<'w, 's> FighterFrameQueryItem<'w, 's> {
             surface: &mut self.surface,
             knockback_velocity: &mut self.knockback_velocity,
             game_settings,
+            animation_root_motion_delta: animation_root_motion_to_gameplay(
+                self.bone_matrices.root_motion_delta(),
+                &self.facing_direction,
+            ),
             animation_frame: self.animation_frame.frame,
             vulnerability: &mut self.vulnerability,
             fighter_attributes: attributes,

src/hitbox_viewer/mod.rs

@@ -41,6 +41,7 @@ pub enum ViewerAttack {
     UpSmash,
     DownSmash,
     ForwardSmash,
+    DashAttack,
 }
 
 impl From<ViewerAttack> for AttackKind {
@@ -58,6 +59,7 @@ impl From<ViewerAttack> for AttackKind {
             ViewerAttack::UpSmash => Self::UpSmash,
             ViewerAttack::DownSmash => Self::DownSmash,
             ViewerAttack::ForwardSmash => Self::ForwardSmash,
+            ViewerAttack::DashAttack => Self::DashAttack,
         }
     }
 }
@@ -100,7 +102,7 @@ struct ViewerState {
     manifest_path: String,
 }
 
-const VIEWER_ATTACKS: [AttackKind; 12] = [
+const VIEWER_ATTACKS: [AttackKind; 13] = [
     AttackKind::NeutralAir,
     AttackKind::ForwardAir,
     AttackKind::BackAir,
@@ -113,6 +115,7 @@ const VIEWER_ATTACKS: [AttackKind; 12] = [
     AttackKind::UpSmash,
     AttackKind::DownSmash,
     AttackKind::ForwardSmash,
+    AttackKind::DashAttack,
 ];
 
 pub struct HitboxViewerPlugin;

src/schedule.rs

@@ -17,14 +17,14 @@ pub enum GameplaySet {
     Input,
     /// Decide whether the current fighter state hands off to another one.
     Interrupt,
+    /// Sample the animation pose selected by the interrupt pass.
+    Animation,
     /// Run the fighter state that survived the interrupt pass.
     StateUpdate,
     /// Integrate velocities into positions.
     Physics,
     /// Resolve the integrated positions against the stage.
     Collision,
-    /// Solve collision boxes
-    Animation,
     /// Resolve attacks
     Attacks,
     /// Advance match rules and detect the end of the match.
@@ -42,9 +42,9 @@ impl Plugin for GameplaySchedulePlugin {
             (
                 GameplaySet::Input,
                 GameplaySet::Interrupt,
+                GameplaySet::Animation,
                 GameplaySet::StateUpdate,
                 GameplaySet::Physics,
-                GameplaySet::Animation,
                 GameplaySet::Collision,
                 GameplaySet::Attacks,
                 GameplaySet::MatchRules,

src/scripting/mod.rs

@@ -17,6 +17,7 @@ pub struct FighterAttackScript {
     pub iasa_frame: Option<u32>,
     pub wont_autocancel_window: Option<(u32, u32)>,
     pub landing_duration: Option<u32>,
+    pub use_root_motion: bool
 }
 
 impl FighterAttackScript {

src/scripting/move_compiler.rs

@@ -17,6 +17,7 @@ struct MoveCompiler {
     iasa_frame: Option<u32>,
     landing_duration: Option<u32>,
     cursor: u32,
+    use_root_motion: bool,
 }
 
 #[derive(Debug, Serialize, Deserialize, Clone)]
@@ -114,6 +115,10 @@ impl MoveCompiler {
         self.iasa_frame = Some(iasa_frame);
     }
 
+    fn enable_root_motion(&mut self) {
+        self.use_root_motion = true;
+    }
+
     fn into_attack_script(mut self) -> Result<FighterAttackScript, String> {
         self.remove_all_hitboxes().map_err(|err| err.to_string())?;
         let mut hitboxes = self.hitboxes;
@@ -124,6 +129,7 @@ impl MoveCompiler {
             iasa_frame: self.iasa_frame,
             wont_autocancel_window: self.wont_autocancel_window,
             landing_duration: self.landing_duration,
+            use_root_motion: self.use_root_motion,
         })
     }
 }
@@ -232,6 +238,18 @@ pub fn compile_script(text: &str) -> Result<FighterAttackScript, String> {
             );
         }
 
+        {
+            let mc = mc.clone();
+            engine.register_fn(
+                "enable_root_motion",
+                move || -> Result<(), Box<EvalAltResult>> {
+                    let mut b = mc.borrow_mut();
+                    b.enable_root_motion();
+                    Ok(())
+                },
+            );
+        }
+
         {
             let mc = mc.clone();
             engine.register_fn(