Fix build

Reviewed-on: #64
Co-authored-by: Álex Román Núñez <eirexe@eirteam.moe>

.gitea/workflows/ci.yml

@@ -130,9 +130,10 @@ jobs:
             libwayland-dev \
             libx11-dev \
             libxfixes3 \
-            libxi \
+            libxi6 \
             libxkbcommon-dev \
             libxkbcommon-x11-0 \
+            blender \
             lld-19 \
             llvm-19 \
             mesa-vulkan-drivers \

src/debug_tools.rs

@@ -3,11 +3,9 @@
 use std::{collections::HashMap, time::Duration};
 
 use bevy::{
-    input::InputSystems,
+    camera::{CameraOutputMode, visibility::RenderLayers}, input::InputSystems, prelude::*, render::render_resource::BlendState, settings::{ReflectSettingsGroup, SaveSettingsDeferred, SettingsGroup},
-    prelude::*,
-    settings::{ReflectSettingsGroup, SaveSettingsDeferred, SettingsGroup},
 };
-use bevy_egui::{EguiContexts, EguiPrimaryContextPass, egui};
+use bevy_egui::{EguiContexts, EguiGlobalSettings, EguiPrimaryContextPass, PrimaryEguiContext, egui};
 use bevy_ggrs::{RollbackFrameRate, RunGgrsSystems};
 use enum_cycling::EnumCycle;
 use enum_cycling_derive::EnumCycle;
@@ -397,6 +395,7 @@ impl Plugin for DebugToolsPlugin {
                     .before(RunGgrsSystems)
                     .run_if(in_state(AppState::InMatch)),
             )
+            .add_systems(Startup, spawn_egui_camera)
             .add_systems(PreUpdate, restore_frame_step_time.after(RunGgrsSystems))
             .add_systems(
                 Update,
@@ -408,6 +407,26 @@ impl Plugin for DebugToolsPlugin {
     }
 }
 
+pub fn spawn_egui_camera(mut commands: Commands, mut egui_global_settings: ResMut<EguiGlobalSettings>,) {
+    egui_global_settings.auto_create_primary_context = false;
+    commands.spawn((
+        // The `PrimaryEguiContext` component requires everything needed to render a primary context.
+        PrimaryEguiContext,
+        Camera2d,
+        // Setting RenderLayers to none makes sure we won't render anything apart from the UI.
+        RenderLayers::none(),
+        Camera {
+            order: 2,
+            output_mode: CameraOutputMode::Write {
+                blend_state: Some(BlendState::ALPHA_BLENDING),
+                clear_color: ClearColorConfig::None,
+            },
+            clear_color: ClearColorConfig::Custom(Color::NONE),
+            ..default()
+        },
+    ));
+}
+
 fn player_handles(players: &Query<&Player>) -> Vec<usize> {
     let mut handles = players
         .iter()

src/debug_tools/save_state.rs

@@ -1,12 +1,22 @@
 use bevy::prelude::*;
 
 use crate::{
-    camera::MatchCamera, fighter::{
+    camera::MatchCamera,
-        FighterECB, FighterFacingDirection, FighterHitboxes, FighterHitstop, FighterHitstopShake, FighterPreviousFacingDirection, FighterPreviousTranslation, FighterTranslation, FighterVelocity, Grounded, animation::FighterAnimationFrame, attack::{
+    fighter::{
+        FighterECB, FighterFacingDirection, FighterHitboxes, FighterHitstop, FighterHitstopShake,
+        FighterPreviousFacingDirection, FighterPreviousTranslation, FighterSurfaceState,
+        FighterTranslation, FighterVelocity,
+        animation::FighterAnimationFrame,
+        attack::{
             FighterDamage, FighterKnockbackVelocity, FighterPendingHitReaction, FighterPendingHits,
             FighterSolvedHurtboxes, FighterStaleMoveQueue,
-        }, baked_animation::FighterBoneMatrices, state::FighterState,
+        },
-    }, input::FighterInput, player::Player, stage::line::StageCollision,
+        baked_animation::FighterBoneMatrices,
+        state::FighterState,
+    },
+    input::FighterInput,
+    player::Player,
+    stage::line::StageCollision,
 };
 
 #[derive(Resource, Default)]
@@ -44,7 +54,7 @@ struct FighterCheckpoint {
     hitboxes: FighterHitboxes,
     solved_hurtboxes: FighterSolvedHurtboxes,
     bone_matrices: FighterBoneMatrices,
-    grounded: bool,
+    surface: FighterSurfaceState,
 }
 
 pub(super) fn save_or_restore(world: &mut World) {
@@ -143,11 +153,7 @@ pub(super) fn save_or_restore(world: &mut World) {
         entity.insert(saved.hitboxes.clone());
         entity.insert(saved.solved_hurtboxes.clone());
         entity.insert(saved.bone_matrices.clone());
-        if saved.grounded {
+        entity.insert(saved.surface.clone());
-            entity.insert(Grounded);
-        } else {
-            entity.remove::<Grounded>();
-        }
     }
     world.insert_resource(checkpoint.pending_hits.clone());
     world.insert_resource(checkpoint.stage_collision);
@@ -181,7 +187,7 @@ fn capture_fighter(world: &World, entity: Entity) -> Option<FighterCheckpoint> {
         hitboxes: fighter.get::<FighterHitboxes>()?.clone(),
         solved_hurtboxes: fighter.get::<FighterSolvedHurtboxes>()?.clone(),
         bone_matrices: fighter.get::<FighterBoneMatrices>()?.clone(),
-        grounded: fighter.contains::<Grounded>(),
+        surface: fighter.get::<FighterSurfaceState>()?.clone(),
     })
 }
 

src/fighter/animation.rs

@@ -84,6 +84,11 @@ pub enum AnimKind {
     AirDodge,
     Fall,
     Turn,
+    CrouchEnter,
+    CrouchIdle,
+    CrouchExit,
+
+    PlatformPass,
 
     FlinchGround,
     FlinchAir,

src/fighter/attack/mod.rs

@@ -605,7 +605,6 @@ impl Plugin for FighterAttackPlugin {
                 intersect_attacks_with_hurtboxes,
             )
                 .chain()
-                .after(crate::fighter::baked_animation::update_fighter_bone_matrices)
                 .in_set(GameplaySet::Attacks),
         );
     }

src/fighter/baked_animation/mod.rs

@@ -219,6 +219,7 @@ mod tests {
         second.translate(FGVec3::lit("0", "3", "0"));
         let mut matrices = FighterBoneMatrices::default();
         matrices.set_pose(
+            AnimKind::Wait,
             &["root".into(), "hand".into()],
             &[None, Some(0)],
             &[first, second],
@@ -239,6 +240,7 @@ mod tests {
         hand.translate(FGVec3::lit("0", "3", "0"));
         let mut matrices = FighterBoneMatrices::default();
         matrices.set_pose(
+            AnimKind::Wait,
             &["root".into(), "hand".into()],
             &[None, Some(0)],
             &[root, hand],
@@ -266,9 +268,9 @@ mod tests {
         let parents = [None, Some(0)];
         let pose = [FixedMat4::IDENTITY, FixedMat4::IDENTITY];
 
-        matrices.set_pose(&names, &parents, &pose, FGi32::ONE);
+        matrices.set_pose(AnimKind::Wait, &names, &parents, &pose, FGi32::ONE);
         let capacities = matrices.buffer_capacities();
-        matrices.set_pose(&names, &parents, &pose, FGi32::ONE);
+        matrices.set_pose(AnimKind::Wait, &names, &parents, &pose, FGi32::ONE);
 
         assert_eq!(capacities, matrices.buffer_capacities());
     }
@@ -281,6 +283,7 @@ mod tests {
         hand.translate(FGVec3::lit("0", "2", "0"));
         let mut matrices = FighterBoneMatrices::default();
         matrices.set_pose(
+            AnimKind::Wait,
             &["root".into(), "hand".into()],
             &[None, Some(0)],
             &[root, hand],

src/fighter/baked_animation/runtime.rs

@@ -71,6 +71,7 @@ pub struct FighterBoneMatrices {
     local_matrices: Vec<FixedMat4>,
     previous_local_matrices: Vec<FixedMat4>,
     model_matrices: Vec<Option<FixedMat4>>,
+    presentation_kind: Option<AnimKind>,
 }
 
 #[derive(Component, Clone, Debug, Default)]
@@ -88,6 +89,12 @@ impl FighterBoneMatrices {
         ]
     }
 
+    pub fn get_by_idx(&self, index: usize) -> Option<(FixedMat4, FixedMat4)> {
+        Some((
+            *self.previous_frame_matrices.get(index)?,
+            *self.matrices.get(index)?,
+        ))
+    }
     pub fn get(&self, bone: &str) -> Option<(FixedMat4, FixedMat4)> {
         let index = self.bone_names.iter().position(|name| name == bone)?;
         Some((
@@ -132,6 +139,7 @@ impl FighterBoneMatrices {
     }
     pub(super) fn set_pose(
         &mut self,
+        kind: AnimKind,
         bone_names: &[String],
         parents: &[Option<usize>],
         local: &[FixedMat4],
@@ -160,6 +168,7 @@ impl FighterBoneMatrices {
         self.previous_local_matrices.reserve(local.len());
         self.model_matrices.reserve(local.len());
         std::mem::swap(&mut self.matrices, &mut self.previous_frame_matrices);
+        let animation_changed = self.presentation_kind != Some(kind);
         std::mem::swap(&mut self.local_matrices, &mut self.previous_local_matrices);
         self.local_matrices.clear();
         self.local_matrices.extend_from_slice(local);
@@ -183,6 +192,14 @@ impl FighterBoneMatrices {
                 model_scale.mul(matrix.expect("baked bone hierarchy should be valid"))
             }),
         );
+        // A state transition is a discontinuity, not an animation frame to
+        // interpolate from the previous clip.  Keep the presentation pose at
+        // the new clip's first/current frame immediately.
+        if animation_changed {
+            self.previous_local_matrices
+                .clone_from(&self.local_matrices);
+        }
+        self.presentation_kind = Some(kind);
     }
 }
 
@@ -212,6 +229,7 @@ pub fn update_fighter_bone_matrices(
             .get(&fighter.manifest)
             .expect("fighter manifest should be loaded before the match starts");
         matrices.set_pose(
+            frame.kind,
             &baked.bone_names,
             &baked.parents,
             pose,

src/fighter/collision.rs

@@ -4,7 +4,7 @@ use crate::fighter::ecb::FighterPreviousECB;
 use crate::fighter::{FighterECB, FighterPreviousTranslation, FighterTranslation};
 use crate::math::segment::FGSegment2d;
 use crate::math::vec::FGVec2;
-use crate::stage::line::{StageCollision, StageLineID};
+use crate::stage::line::{StageCollision, StageLineID, StagePolyType};
 /*
 pub fn collide_fighter_with_scene(
     fighters: Query<(&FighterECB, &mut FighterVelocity, &mut FighterTranslation)>,
@@ -44,6 +44,8 @@ pub fn air_collide_with_stage(
     prev_ecb: &FighterPreviousECB,
     ecb: &FighterECB,
     stage_collision: &StageCollision,
+    ignored_polys: &[usize],
+    ignore_soft_platforms: bool,
 ) -> Option<AirCollisionWithStageResult> {
     let ray_segment = FGSegment2d::new(
         prev_translation.0 + prev_ecb.get_bottom_point(),
@@ -54,6 +56,10 @@ pub fn air_collide_with_stage(
         .stage_polys
         .iter()
         .enumerate()
+        .filter(|(poly_idx, poly)| {
+            !ignored_polys.contains(poly_idx)
+                && !(ignore_soft_platforms && matches!(poly.poly_type, StagePolyType::Platform))
+        })
         .filter_map(|(poly_idx, poly)| {
             poly.intersect_ray(ray_segment).map(|intersect_result| {
                 (
@@ -76,3 +82,134 @@ pub fn air_collide_with_stage(
         .max_by(|(_, a), (_, b)| a.cmp(b))
         .map(|(result, _)| result)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::fighter::ecb::{FighterECB, FighterPreviousECB};
+    use crate::stage::line::{StagePoly, StagePolyLineSegmentType, StagePolyType};
+
+    fn horizontal_platform(y: &str) -> StagePoly {
+        StagePoly::build(
+            StagePolyType::Platform,
+            &[
+                (FGVec2::lit("-2", y), StagePolyLineSegmentType::Floor),
+                (FGVec2::lit("2", y), StagePolyLineSegmentType::Floor),
+            ],
+        )
+    }
+
+    fn solid_floor() -> StagePoly {
+        StagePoly::build(
+            StagePolyType::Closed,
+            &[
+                (FGVec2::lit("-2", "0"), StagePolyLineSegmentType::Floor),
+                (FGVec2::lit("2", "0"), StagePolyLineSegmentType::Floor),
+                (FGVec2::lit("2", "-2"), StagePolyLineSegmentType::Wall),
+                (FGVec2::lit("-2", "-2"), StagePolyLineSegmentType::Wall),
+            ],
+        )
+    }
+
+    #[test]
+    fn airborne_collision_skips_ignored_polygons() {
+        let stage_collision = StageCollision {
+            stage_polys: vec![horizontal_platform("0"), horizontal_platform("1")],
+        };
+        let previous_translation = FighterPreviousTranslation(FGVec2::lit("0", "2"));
+        let translation = FighterTranslation(FGVec2::lit("0", "-1"));
+        let previous_ecb = FighterPreviousECB {
+            bottom: FGVec2::ZERO,
+            top: FGVec2::ZERO,
+            left: FGVec2::ZERO,
+            right: FGVec2::ZERO,
+        };
+        let ecb = FighterECB {
+            bottom: FGVec2::ZERO,
+            top: FGVec2::ZERO,
+            left: FGVec2::ZERO,
+            right: FGVec2::ZERO,
+        };
+
+        let collision = air_collide_with_stage(
+            &previous_translation,
+            &translation,
+            &previous_ecb,
+            &ecb,
+            &stage_collision,
+            &[1],
+            false,
+        )
+        .expect("the non-ignored platform should still be collidable");
+
+        assert_eq!(collision.line_id.polygon, 0);
+        assert_eq!(collision.hit_position, FGVec2::lit("0", "0"));
+    }
+
+    #[test]
+    fn airborne_collision_skips_soft_platforms_while_passing_down() {
+        let stage_collision = StageCollision {
+            stage_polys: vec![horizontal_platform("0")],
+        };
+        let previous_translation = FighterPreviousTranslation(FGVec2::lit("0", "2"));
+        let translation = FighterTranslation(FGVec2::lit("0", "-1"));
+        let previous_ecb = FighterPreviousECB {
+            bottom: FGVec2::ZERO,
+            top: FGVec2::ZERO,
+            left: FGVec2::ZERO,
+            right: FGVec2::ZERO,
+        };
+        let ecb = FighterECB {
+            bottom: FGVec2::ZERO,
+            top: FGVec2::ZERO,
+            left: FGVec2::ZERO,
+            right: FGVec2::ZERO,
+        };
+
+        assert!(air_collide_with_stage(
+            &previous_translation,
+            &translation,
+            &previous_ecb,
+            &ecb,
+            &stage_collision,
+            &[],
+            true,
+        )
+        .is_none());
+    }
+
+    #[test]
+    fn airborne_collision_still_hits_solid_floors_while_passing_down() {
+        let stage_collision = StageCollision {
+            stage_polys: vec![solid_floor()],
+        };
+        let previous_translation = FighterPreviousTranslation(FGVec2::lit("0", "2"));
+        let translation = FighterTranslation(FGVec2::lit("0", "-1"));
+        let previous_ecb = FighterPreviousECB {
+            bottom: FGVec2::ZERO,
+            top: FGVec2::ZERO,
+            left: FGVec2::ZERO,
+            right: FGVec2::ZERO,
+        };
+        let ecb = FighterECB {
+            bottom: FGVec2::ZERO,
+            top: FGVec2::ZERO,
+            left: FGVec2::ZERO,
+            right: FGVec2::ZERO,
+        };
+
+        let collision = air_collide_with_stage(
+            &previous_translation,
+            &translation,
+            &previous_ecb,
+            &ecb,
+            &stage_collision,
+            &[],
+            true,
+        )
+        .expect("solid floors remain collidable while passing down");
+
+        assert_eq!(collision.line_id.polygon, 0);
+        assert_eq!(collision.hit_position, FGVec2::lit("0", "0"));
+    }
+}

src/fighter/debug.rs

@@ -27,6 +27,7 @@ use crate::game_settings::GameSettings;
 use crate::input::FighterInput;
 use crate::math::int::FGi32;
 use crate::math::vec::FGVec2;
+use crate::math::vec3::FGVec3;
 use crate::player::Player;
 
 pub fn debug_draw_ecb(
@@ -39,6 +40,12 @@ pub fn debug_draw_ecb(
     mut gizmos: Gizmos,
 ) {
     for (ecb, trf, ecb_prev, trf_prev) in ecbs {
+        gizmos.cross(
+            FGVec3::new(trf.0.x, trf.0.y, FGi32::ZERO).to_vec3(),
+            2.0,
+            bevy::color::palettes::css::BLUE,
+        );
+
         let transformed =
             ecb.to_3d_lineloop(Transform::from_xyz(trf.x.to_num(), trf.y.to_num(), 0.0));
         gizmos.lineloop(transformed, YELLOW);
@@ -153,10 +160,17 @@ pub fn fighter_debug(
     Ok(())
 }
 
-pub fn animation_debug(query: Query<(&GlobalTransform, &FighterBoneMatrices)>, mut gizmos: Gizmos) {
+pub fn animation_debug(
-    for (global_transform, matrices) in query {
+    query: Query<(
-        let (_, rotation, translation) = global_transform.to_scale_rotation_translation();
+        &FighterTranslation,
-        let marker_transform = Transform::from_translation(translation).with_rotation(rotation);
+        &FighterFacingDirection,
+        &FighterBoneMatrices,
+    )>,
+    mut gizmos: Gizmos,
+) {
+    for (global_transform, facing_dir, matrices) in query {
+        let global_transform = global_transform.get_3d_transform(facing_dir);
+        let marker_transform = global_transform.to_mat4();
         for (_, matrix) in matrices.iter() {
             let pos = marker_transform.transform_point(Vec3::new(
                 matrix.cols[3][0].to_num(),

src/fighter/ecb.rs

@@ -1,28 +1,44 @@
 use bevy::prelude::*;
 
-use crate::math::{int::FGi32, vec::FGVec2};
+use crate::{
+    fighter::{
+        FighterFacingDirection, FighterSurfaceState, FighterTranslation,
+        baked_animation::FighterBoneMatrices,
+    }, math::{int::FGi32, vec::FGVec2},
+};
 
 /// Environment collision box: the diamond used to resolve a fighter against
 /// the stage. Purely geometry — the collision response lives in
 /// [`super::collision`].
-#[derive(Component, Debug, Clone, Copy, Hash)]
+#[derive(Component, Debug, Clone, Copy, Hash, Default)]
 #[require(FighterPreviousECB)]
 pub struct FighterECB {
-    pub vertical_half: FGi32,
+    pub top: FGVec2,
-    pub horizontal_half: FGi32,
+    pub bottom: FGVec2,
+    pub left: FGVec2,
+    pub right: FGVec2,
+}
+
+#[derive(Component, Debug, Clone)]
+pub struct FighterECBBoneIndices {
+    pub indices: Vec<usize>,
 }
 
 #[derive(Component, Debug, Clone, Copy, Default, Hash)]
 pub struct FighterPreviousECB {
-    pub vertical_half: FGi32,
+    pub top: FGVec2,
-    pub horizontal_half: FGi32,
+    pub bottom: FGVec2,
+    pub left: FGVec2,
+    pub right: FGVec2,
 }
 
 impl From<FighterECB> for FighterPreviousECB {
     fn from(ecb: FighterECB) -> Self {
         Self {
-            vertical_half: ecb.vertical_half,
+            top: ecb.top,
-            horizontal_half: ecb.horizontal_half,
+            bottom: ecb.bottom,
+            left: ecb.left,
+            right: ecb.right,
         }
     }
 }
@@ -35,53 +51,85 @@ pub fn snapshot_fighter_ecb(fighters: Query<(&FighterECB, &mut FighterPreviousEC
 
 impl FighterECB {
     pub fn to_3d_lineloop(&self, trf: Transform) -> [Vec3; 4] {
-        let rel_up = trf.transform_point(Vec3::new(
+        [self.top, self.right, self.bottom, self.left]
-            0.0,
+            .map(|point| trf.transform_point(Vec3::new(point.x.to_num(), point.y.to_num(), 0.0)))
-            (self.vertical_half + self.vertical_half).to_num(),
-            0.0,
-        ));
-        let rel_down = trf.transform_point(Vec3::new(0.0, 0.0, 0.0));
-        let rel_left = trf.transform_point(Vec3::new(
-            (-self.horizontal_half).to_num(),
-            self.vertical_half.to_num(),
-            0.0,
-        ));
-        let rel_right = trf.transform_point(Vec3::new(
-            self.horizontal_half.to_num(),
-            self.vertical_half.to_num(),
-            0.0,
-        ));
-        [rel_up, rel_right, rel_down, rel_left]
     }
 
     pub fn get_bottom_point(&self) -> FGVec2 {
-        FGVec2::new(FGi32::ZERO, FGi32::ZERO)
+        self.bottom
     }
 }
 
 impl FighterPreviousECB {
     pub fn to_3d_lineloop(&self, trf: Transform) -> [Vec3; 4] {
-        let rel_up = trf.transform_point(Vec3::new(
+        [self.top, self.right, self.bottom, self.left]
-            0.0,
+            .map(|point| trf.transform_point(Vec3::new(point.x.to_num(), point.y.to_num(), 0.0)))
-            (self.vertical_half + self.vertical_half).to_num(),
-            0.0,
-        ));
-        let rel_down = trf.transform_point(Vec3::new(0.0, 0.0, 0.0));
-        let rel_left = trf.transform_point(Vec3::new(
-            (-self.horizontal_half).to_num(),
-            self.vertical_half.to_num(),
-            0.0,
-        ));
-        let rel_right = trf.transform_point(Vec3::new(
-            self.horizontal_half.to_num(),
-            self.vertical_half.to_num(),
-            0.0,
-        ));
-        [rel_up, rel_right, rel_down, rel_left]
     }
 
     pub fn get_bottom_point(&self) -> FGVec2 {
-        FGVec2::new(FGi32::ZERO, FGi32::ZERO)
+        self.bottom
+    }
+}
+
+pub fn update_ecb(
+    query: Query<(
+        &mut FighterECB,
+        &FighterSurfaceState,
+        &FighterECBBoneIndices,
+        &FighterBoneMatrices,
+        &FighterTranslation,
+        &FighterFacingDirection,
+    )>,
+) {
+    for (mut ecb, surface_state, bone_indices, bone_matrices, translation, facing_dir) in query {
+        let trf = translation.get_3d_transform(facing_dir);
+
+        let transformed_ecb_bones = bone_indices.indices.iter().filter_map(|idx| {
+            let Some((_, bone_matrix)) = bone_matrices.get_by_idx(*idx) else {
+                return None;
+            };
+
+            let pt = trf.transform_point(bone_matrix.get_translation());
+
+            Some(FGVec2::new(pt.x, pt.y) - translation.0)
+        }).collect::<Vec<_>>();
+
+        let max_x = transformed_ecb_bones.iter().max_by(|a, b| a.x.cmp(&b.x)).map(|final_val| final_val.x).unwrap_or(FGi32::lit("0.5"));
+        let min_x = transformed_ecb_bones.iter().min_by(|a, b| a.x.cmp(&b.x)).map(|final_val| final_val.x).unwrap_or(FGi32::lit("-0.5"));
+        let max_y = transformed_ecb_bones.iter().max_by(|a, b| a.y.cmp(&b.y)).map(|final_val| final_val.y).unwrap_or(FGi32::lit("0.5"));
+        let min_y = transformed_ecb_bones.iter().min_by(|a, b| a.y.cmp(&b.y)).map(|final_val| final_val.y).unwrap_or(FGi32::lit("-0.5"));
+
+        let midpoint_height = (max_y + min_y) / FGi32::lit("2.0");
+        let top = FGVec2::new(FGi32::ZERO, max_y);
+        let bottom = FGVec2::new(FGi32::ZERO, min_y);
+        let left = FGVec2::new(min_x, midpoint_height);
+        let right = FGVec2::new(max_x, midpoint_height);
+
+        let ecb_lock_frames_remaining = if let FighterSurfaceState::Airborne { ecb_lock_frames_remaining, .. } = surface_state {
+            *ecb_lock_frames_remaining
+        } else {
+            0
+        };
+
+        ecb.top = top;
+
+        if ecb_lock_frames_remaining == 0 {
+            ecb.bottom = bottom;
+        }
+
+        ecb.left = left;
+        ecb.right = right;
+
+        if surface_state.is_grounded() {
+            ecb.bottom = FGVec2::ZERO;
+        }
+    }
+}
+
+pub fn decrement_ecb_lockout(surface_states: Query<&mut FighterSurfaceState>) {
+    for mut state in surface_states {
+        state.tick_ecb_lock();
+        state.tick_ignored_polygons();
     }
 }
 
@@ -92,12 +140,16 @@ mod tests {
     #[test]
     fn previous_ecb_copies_current_dimensions() {
         let current = FighterECB {
-            vertical_half: FGi32::lit("0.5"),
+            bottom: FGVec2::lit("0.0", "-0.5"),
-            horizontal_half: FGi32::lit("0.25"),
+            top: FGVec2::lit("0.0", "0.5"),
+            left: FGVec2::lit("-0.5", "0.0"),
+            right: FGVec2::lit("0.5", "0.0"),
         };
         let previous = FighterPreviousECB::from(current);
 
-        assert_eq!(previous.vertical_half, current.vertical_half);
+        assert_eq!(previous.top, current.top);
-        assert_eq!(previous.horizontal_half, current.horizontal_half);
+        assert_eq!(previous.bottom, current.bottom);
+        assert_eq!(previous.left, current.left);
+        assert_eq!(previous.right, current.right);
     }
 }

src/fighter/manifest.rs

@@ -65,6 +65,7 @@ pub struct FighterManifest {
     pub animations: HashMap<AnimKind, String>,
     pub attack_scripts: HashMap<AttackKind, String>,
     pub hurtboxes: Vec<FighterHurtbox>,
+    pub ecb_bones: Vec<String>,
 }
 
 #[derive(Resource)]

src/fighter/mod.rs

@@ -18,6 +18,7 @@ pub mod hurtbox;
 pub mod manifest;
 pub mod motion;
 pub mod state;
+pub mod surface;
 pub mod visual;
 
 // The fighter components are re-exported so the rest of the crate can say
@@ -28,9 +29,9 @@ pub use attributes::FighterAttributes;
 pub use ecb::FighterECB;
 pub use manifest::FighterId;
 pub use motion::{
-    FighterPreviousFacingDirection, FighterPreviousTranslation, FighterTranslation,
+    FighterPreviousFacingDirection, FighterPreviousTranslation, FighterTranslation, FighterVelocity,
-    FighterVelocity, Grounded,
 };
+pub use surface::FighterSurfaceState;
 
 use crate::{
     AppState, fighter::{
@@ -38,7 +39,7 @@ use crate::{
             AttackKind, FighterAttackPlugin, FighterAttackScriptAssets, FighterDamage,
             FighterKnockbackVelocity, FighterPendingHitReaction, FighterSolvedHurtboxes,
             FighterStaleMoveQueue,
-        }, baked_animation::{FighterBoneIndexMap, FighterBoneMatrices}, manifest::FighterManifest, state::{FighterState, air::AirborneStateCommon, fall::FallState}, visual::FighterAnimations,
+        }, baked_animation::{FighterBoneIndexMap, FighterBoneMatrices}, ecb::FighterECBBoneIndices, manifest::FighterManifest, state::{FighterState, air::AirborneStateCommon, fall::FallState}, visual::FighterAnimations,
     }, input::FighterInput, math::{int::FGi32, vec::FGVec2}, player::Player, schedule::GameplaySet, scripting::FighterAttackScript, stage::line::StageCollision,
 };
 use state::state_interrupt_system;
@@ -58,14 +59,14 @@ pub enum FighterFacingDirection {
 pub enum FighterHitstopShakeKind {
     #[default]
     Horizontal,
-    Vertical
+    Vertical,
 }
 
 #[derive(Component, Copy, Clone, Hash, Debug, PartialEq, Reflect, Default)]
 pub enum FighterHitstopShakeRole {
     #[default]
     Attacker,
-    Receiver
+    Receiver,
 }
 
 #[derive(Component, Default, Copy, Clone, Hash)]
@@ -73,7 +74,7 @@ pub struct FighterHitstopShake {
     pub remaining_frames: u32,
     pub total_frames: u32,
     pub kind: FighterHitstopShakeKind,
-    pub role: FighterHitstopShakeRole
+    pub role: FighterHitstopShakeRole,
 }
 
 #[derive(Component, Default, Copy, Clone, Hash)]
@@ -133,7 +134,7 @@ pub struct FighterVisual;
     FighterPendingHitReaction,
     FighterHitstop,
     FighterKnockbackVelocity,
-    FighterTranslation,
+    FighterTranslation
 )]
 pub struct Fighter {
     pub manifest: Handle<FighterManifest>,
@@ -170,10 +171,15 @@ impl Plugin for FighterPlugin {
             )*/
             .add_systems(
                 GgrsSchedule,
-                state::state_collision_interrupt_system.in_set(GameplaySet::Collision),
+                (
+                    (ecb::update_ecb, ecb::decrement_ecb_lockout, state::state_collision_interrupt_system).chain(),
+                    baked_animation::update_fighter_bone_matrices,
+                )
+                    .chain()
+                    .in_set(GameplaySet::Collision),
             )
             .add_systems(
-                Update,
+                PostUpdate,
                 (
                     motion::apply_fighter_translation_to_visuals,
                     animation::apply_animation,
@@ -200,8 +206,8 @@ impl Plugin for FighterPlugin {
             .checksum_component_with_hash::<FighterPreviousFacingDirection>()
             .rollback_component_with_copy::<animation::FighterAnimationFrame>()
             .checksum_component_with_hash::<animation::FighterAnimationFrame>()
-            .rollback_component_with_copy::<Grounded>()
+            .rollback_component_with_clone::<FighterSurfaceState>()
-            .checksum_component_with_hash::<Grounded>()
+            .checksum_component_with_hash::<FighterSurfaceState>()
             .rollback_component_with_copy::<FighterFacingDirection>()
             .rollback_component_with_copy::<FighterDamage>()
             .checksum_component_with_hash::<FighterDamage>()
@@ -259,7 +265,7 @@ pub struct FighterActiveAttack {
     pub active_hitboxes: Vec<usize>,
     pub solved_hitboxes: Vec<attack::FighterSolvedHitbox>,
     pub hit_fighters: Vec<Entity>,
-    pub stalled: bool
+    pub stalled: bool,
 }
 
 #[derive(Component, Clone, Debug, Default, Hash)]
@@ -274,6 +280,7 @@ pub fn spawn_fighter(
     animations: FighterAnimations,
     attack_scripts: FighterAttackScriptAssets,
     visual_root: WorldAssetRoot,
+    ecb_bone_indices: Vec<usize>,
 ) -> Entity {
     commands
         .spawn((
@@ -284,13 +291,14 @@ pub fn spawn_fighter(
             Fighter { manifest: manifest },
             FighterFacingDirection::Right,
             FighterPreviousFacingDirection(FighterFacingDirection::Right),
+            FighterSurfaceState::default(),
             Transform::from_scale(Vec3::splat(model_scale.to_num())),
             (
-                FighterECB {
+                FighterECB::default(),
-                    vertical_half: FGi32::lit("5.0"),
-                    horizontal_half: FGi32::lit("2.5"),
-                },
                 FighterHitboxes::default(),
+                FighterECBBoneIndices {
+                    indices: ecb_bone_indices
+                }
             ),
             (
                 FighterVelocity::default(),

src/fighter/motion.rs

@@ -5,19 +5,16 @@ use bevy::prelude::*;
 use bevy_ggrs::GgrsFrameTiming;
 
 use crate::debug_tools::PresentationMotionMode;
-use crate::fighter::{FighterHitstopShake};
+use crate::fighter::FighterHitstopShake;
 use crate::game_settings::GameSettings;
 use crate::{
-    fighter::{FighterECB, FighterFacingDirection, baked_animation::FixedMat4},
+    fighter::{FighterFacingDirection, baked_animation::FixedMat4},
     math::{int::FGi32, vec::FGVec2, vec3::FGVec3},
 };
 
 #[derive(Component, Clone, Copy, Hash)]
 pub struct FighterPreviousFacingDirection(pub FighterFacingDirection);
 
-#[derive(Component, Clone, Copy, Hash)]
-pub struct Grounded;
-
 #[derive(Component, Deref, DerefMut, Default, Debug, Clone, Copy, Hash)]
 pub struct FighterVelocity(pub FGVec2);
 
@@ -59,7 +56,6 @@ pub fn apply_fighter_translation_to_visuals(
     query: Query<(
         &FighterTranslation,
         &FighterPreviousTranslation,
-        &FighterECB,
         &FighterHitstopShake,
         &mut Transform,
     )>,
@@ -68,33 +64,42 @@ pub fn apply_fighter_translation_to_visuals(
     game_settings: Res<GameSettings>,
 ) {
     let overstep_fraction = timing.overstep_fraction();
-    for (translation, previous_translation, ecb, hitstop_shake, mut transform) in query {
+    for (translation, previous_translation, hitstop_shake, mut transform) in query {
         let translation = sample_presentation_translation(
             *previous_translation,
             *translation,
             overstep_fraction,
             debug_settings.motion_sampling,
         );
-        let bottom = ecb.get_bottom_point();
         transform.translation = Vec3::new(
-            translation.x + bottom.x.to_num::<f32>(),
+            translation.x,
-            translation.y + bottom.y.to_num::<f32>(),
+            translation.y,
             0.0,
         );
 
-        if hitstop_shake.remaining_frames > 0 && hitstop_shake.total_frames > 0 && !game_settings.fighter_common.visual_shake_table.is_empty() {
+        if hitstop_shake.remaining_frames > 0
+            && hitstop_shake.total_frames > 0
+            && !game_settings.fighter_common.visual_shake_table.is_empty()
+        {
             let total = hitstop_shake.total_frames as f32;
             let curr = hitstop_shake.remaining_frames as f32;
             let elapsed = 1.0 - curr / total;
 
-            
+            let access_index = (hitstop_shake.remaining_frames as usize)
-            let access_index = (hitstop_shake.remaining_frames as usize) % game_settings.fighter_common.visual_shake_table.len();
+                % game_settings.fighter_common.visual_shake_table.len();
             let shake_multiplier = match hitstop_shake.role {
-                super::FighterHitstopShakeRole::Attacker => game_settings.fighter_common.attacker_visual_shake_multiplier,
+                super::FighterHitstopShakeRole::Attacker => {
+                    game_settings
+                        .fighter_common
+                        .attacker_visual_shake_multiplier
+                }
                 super::FighterHitstopShakeRole::Receiver => 1.0,
             };
-            let shake_amount: f32 = 1.0 - EaseFunction::QuinticIn.sample(elapsed).unwrap_or_default();
+            let shake_amount: f32 =
-            let shake_amount = game_settings.fighter_common.visual_shake_table[access_index] * shake_amount * shake_multiplier;
+                1.0 - EaseFunction::QuinticIn.sample(elapsed).unwrap_or_default();
+            let shake_amount = game_settings.fighter_common.visual_shake_table[access_index]
+                * shake_amount
+                * shake_multiplier;
 
             let shake_offset = match hitstop_shake.kind {
                 super::FighterHitstopShakeKind::Horizontal => Vec3::new(shake_amount, 0.0, 0.0),

src/fighter/state/air.rs

@@ -1,4 +1,3 @@
-use crate::fighter::state::ground::GroundedStateCommon;
 use crate::fighter::state::land::{LandingState, LandingType};
 use crate::fighter::state::{CollisionContext, FighterState};
 use crate::fighter::*;
@@ -30,7 +29,7 @@ pub fn process_fast_fall(
 pub fn integrate_gravity(
     velocity: &mut FighterVelocity,
     attributes: &FighterAttributes,
-    fast_fall: bool
+    fast_fall: bool,
 ) {
     velocity.y -= attributes.gravity;
 
@@ -94,10 +93,23 @@ pub fn update_standard_motion(
     ctx: &mut crate::fighter::state::UpdateContext,
     airborne_common: &mut AirborneStateCommon,
 ) {
-    process_fast_fall(airborne_common, ctx.input, &mut ctx.velocity, ctx.fighter_attributes);
+    process_fast_fall(
-    integrate_gravity(ctx.velocity, ctx.fighter_attributes, airborne_common.is_fast_falling);
+        airborne_common,
+        ctx.input,
+        &mut ctx.velocity,
+        ctx.fighter_attributes,
+    );
+    integrate_gravity(
+        ctx.velocity,
+        ctx.fighter_attributes,
+        airborne_common.is_fast_falling,
+    );
     apply_air_drift(ctx.velocity, ctx.fighter_attributes, ctx.input);
-    apply_air_motion(ctx.velocity, ctx.translation, ctx.prev_translation);
+    apply_air_motion(
+        ctx.velocity,
+        ctx.translation,
+        ctx.prev_translation,
+    );
 }
 
 pub fn collision_interrupt(
@@ -105,14 +117,14 @@ pub fn collision_interrupt(
     landing_type: LandingType,
 ) -> Option<FighterState> {
     let res = ctx.air_collide_with_stage()?;
-    ctx.translation.0 = res.hit_position - ctx.ecb.get_bottom_point();
+    let diff = res.hit_position - ctx.translation.0;
-    let grounded_common = GroundedStateCommon {
+    ctx.ecb.bottom -= diff;
-        current_line_id: res.line_id,
+    ctx.ecb.top -= diff;
-    };
+    ctx.ecb.left -= diff;
-    Some(FighterState::Land(LandingState::create(
+    ctx.ecb.right -= diff;
-        grounded_common,
+    ctx.translation.0 = res.hit_position;
-        landing_type,
+    ctx.surface.land(res.line_id);
-    )))
+    Some(FighterState::Land(LandingState::create(landing_type)))
 }
 
 #[cfg(test)]

src/fighter/state/air_dodge.rs

@@ -1,9 +1,16 @@
 use crate::{
     fighter::{
-        animation::AnimKind, state::{
+        animation::AnimKind,
-            CollisionContext, EnterContext, FighterState, FighterStateImpl, InterruptContext, UpdateContext, air::{self, AirborneStateCommon}, fall::FallState, land::LandingType,
+        state::{
+            CollisionContext, EnterContext, FighterState, FighterStateImpl, InterruptContext,
+            UpdateContext,
+            air::{self, AirborneStateCommon},
+            fall::FallState,
+            land::LandingType,
         },
-    }, input, math::vec::FGVec2,
+    },
+    input,
+    math::vec::FGVec2,
 };
 
 #[derive(Debug, Clone, Hash)]
@@ -16,7 +23,9 @@ impl FighterStateImpl for AirDodgeState {
 
     fn check_interrupt(&self, state_context: &mut InterruptContext) -> Option<FighterState> {
         if state_context.is_current_animation_finished() {
-            Some(FighterState::Fall(FallState::new(AirborneStateCommon::default())))
+            Some(FighterState::Fall(FallState::new(
+                AirborneStateCommon::default(),
+            )))
         } else {
             None
         }
@@ -46,11 +55,13 @@ impl FighterStateImpl for AirDodgeState {
             self.direction * state_context.fighter_attributes.air_dodge_velocity;
     }
 
-    fn is_visually_grounded<'a>(
+    fn is_visually_grounded<'a>(&'a self) -> bool {
-        &'a self,
-    ) -> bool {
         false
     }
+
+    fn surface_policy(&self) -> super::SurfacePolicy {
+        super::SurfacePolicy::Airborne(crate::fighter::surface::EcbLockPolicy::StartOnDetach)
+    }
 }
 
 pub fn check_input(state_context: &InterruptContext) -> Option<FighterState> {

src/fighter/state/crouch.rs

@@ -0,0 +1,160 @@
+use super::{
+    CollisionContext, EnterContext, FighterStateImpl, InterruptContext, UpdateContext, ground,
+};
+use crate::fighter::FighterSurfaceState;
+use crate::fighter::animation::AnimKind;
+use crate::fighter::state::air::AirborneStateCommon;
+use crate::fighter::state::ground::{
+    grounded_movement_common_interrupts, grounded_movement_standstill_common_interrupts,
+};
+use crate::fighter::state::platform_pass::PlatformPassState;
+use crate::fighter::state::{FighterState, dash, ground_attack, turn, walk};
+use crate::input::FighterCommands;
+use crate::stage::line::StagePolyType;
+
+#[derive(Debug, Clone, Hash)]
+pub enum CrouchSubState {
+    Entering { pass_queued: bool },
+    Idle,
+    Exiting,
+}
+
+#[derive(Debug, Clone, Hash)]
+pub struct CrouchState {
+    sub_state: CrouchSubState,
+}
+
+pub fn crouch_idle_interrupts(state_context: &InterruptContext) -> Option<FighterState> {
+    if let Some(state) = ground_attack::check_interrupt(state_context) {
+        Some(state)
+    } else if let Some(state) = dash::check_input(state_context) {
+        Some(state)
+    } else if let Some(state) = turn::check_input(state_context) {
+        Some(state)
+    } else if let Some(state) = walk::check_input(state_context) {
+        Some(state)
+    } else {
+        None
+    }
+}
+
+pub fn crouch_entering_interrupts(state_context: &InterruptContext) -> Option<FighterState> {
+    if let Some(state) = ground_attack::check_interrupt(state_context) {
+        Some(state)
+    } else {
+        None
+    }
+}
+
+impl FighterStateImpl for CrouchState {
+    const NAME: &'static str = "Crouch";
+    fn check_interrupt(&self, state_context: &mut InterruptContext) -> Option<FighterState> {
+        if let Some(state) = grounded_movement_common_interrupts(state_context) {
+            return Some(state);
+        }
+
+        match self.sub_state {
+            CrouchSubState::Entering { pass_queued } => {
+                // pass
+                if let FighterSurfaceState::Grounded { line_id } = state_context.surface {
+                    if let Some(stage_poly) = state_context
+                        .stage_collision
+                        .stage_polys
+                        .get(line_id.polygon)
+                    {
+                        let is_inputting_crouch = -state_context.game_settings.input_common.run_stick_threshold > state_context.input.get_last_frame().movement.y;
+                        let is_on_a_soft_platform = matches!(stage_poly.poly_type, StagePolyType::Platform);
+                        if pass_queued && is_inputting_crouch && is_on_a_soft_platform 
+                        {
+                            return Some(FighterState::PlatformPass(PlatformPassState::new(
+                                AirborneStateCommon::default(),
+                                line_id.polygon,
+                            )));
+                        }
+                    }
+                }
+
+                // While entering the crouch animation we do not allow movement inputs, but we do allow attacks and jumps
+                if state_context.is_current_animation_finished() {
+                    return Some(FighterState::Crouch(CrouchState {
+                        sub_state: CrouchSubState::Idle,
+                    }));
+                } else {
+                    return crouch_entering_interrupts(state_context);
+                }
+            }
+            CrouchSubState::Idle => {
+                if state_context.input.get_last_frame().movement.y
+                    > -state_context.game_settings.input_common.run_stick_threshold
+                {
+                    return Some(FighterState::Crouch(CrouchState {
+                        sub_state: CrouchSubState::Exiting,
+                    }));
+                } else {
+                    return crouch_idle_interrupts(state_context);
+                }
+            }
+            CrouchSubState::Exiting => {
+                if state_context.is_current_animation_finished() {
+                    return grounded_movement_standstill_common_interrupts(state_context);
+                } else {
+                    return crouch_idle_interrupts(state_context);
+                }
+            }
+        }
+    }
+
+    fn on_enter(&mut self, state_context: &mut EnterContext) {
+        match self.sub_state {
+            CrouchSubState::Entering { .. } => {
+                state_context.play_animation(AnimKind::CrouchEnter, false);
+            }
+            CrouchSubState::Idle => {
+                state_context.play_animation(AnimKind::CrouchIdle, true);
+            }
+            CrouchSubState::Exiting => {
+                state_context.play_animation(AnimKind::CrouchExit, false);
+            }
+        }
+    }
+
+    fn update(&mut self, state_context: &mut UpdateContext) {
+        if let CrouchSubState::Entering {
+            pass_queued,
+        } = &mut self.sub_state
+        {
+            if state_context
+                .input
+                .has_command(FighterCommands::SmashMoveDown)
+            {
+                state_context
+                    .input
+                    .clear_command(FighterCommands::SmashMoveDown);
+                *pass_queued = true;
+            }
+        }
+        ground::update_friction_motion(state_context);
+    }
+
+    fn check_collision_interrupt(
+        &mut self,
+        state_context: &mut CollisionContext,
+    ) -> Option<FighterState> {
+        ground::collision_interrupt(state_context, false)
+    }
+
+    fn is_visually_grounded<'a>(&'a self) -> bool {
+        true
+    }
+}
+
+pub fn check_input(state_context: &InterruptContext) -> Option<FighterState> {
+    let input_frame = state_context.input.get_last_frame();
+
+    if input_frame.movement.y <= -state_context.game_settings.input_common.run_stick_threshold {
+        return Some(FighterState::Crouch(CrouchState {
+            sub_state: CrouchSubState::Entering { pass_queued: false },
+        }));
+    }
+    None
+}

src/fighter/state/dash.rs

@@ -5,52 +5,43 @@ use super::{
 use crate::fighter::FighterFacingDirection;
 use crate::fighter::animation::AnimKind;
 use crate::fighter::state::FighterState;
-use crate::fighter::state::ground::GroundedStateCommon;
 use crate::input::FighterCommands::{SmashMoveLeft, SmashMoveRight};
 
 #[derive(Debug, Clone, Hash)]
 pub struct DashState {
     direction: FighterFacingDirection,
-    pub ground_common: GroundedStateCommon,
 }
 
 impl DashState {
-    pub fn new(direction: FighterFacingDirection, ground_common: GroundedStateCommon) -> Self {
+    pub fn new(direction: FighterFacingDirection) -> Self {
-        Self {
+        Self { direction }
-            direction,
-            ground_common,
-        }
     }
 }
 
 impl FighterStateImpl for DashState {
     const NAME: &'static str = "Dash";
     fn check_interrupt(&self, ctx: &mut InterruptContext) -> Option<FighterState> {
-        let ground = &self.ground_common;
         let attributes = ctx.fighter_attributes;
 
         // A reverse dash can interrupt before IASA
         if let Some(direction) =
             check_smash_input_with_dir(ctx).filter(|direction| *direction != self.direction)
         {
-            return Some(FighterState::Dash(DashState::new(
+            return Some(FighterState::Dash(DashState::new(direction)));
-                direction,
-                ground.clone(),
-            )));
         }
 
-        if let Some(state) = ground::grounded_movement_common_interrupts(ctx, ground) {
+        if let Some(state) = ground::grounded_movement_common_interrupts(ctx) {
             return Some(state);
         }
 
         if ctx.is_current_animation_finished() {
-            return run::check_input(ctx, ground)
+            return run::check_input(ctx)
-                .or_else(|| walk::check_input(ctx, ground))
+                .or_else(|| walk::check_input(ctx))
-                .or_else(|| wait::check_input(ctx, ground));
+                .or_else(|| wait::check_input(ctx));
         }
 
         if ctx.get_current_animation_frame() > attributes.dash_acceleration_duration {
-            return run::check_input(ctx, ground);
+            return run::check_input(ctx);
         }
 
         None
@@ -106,12 +97,10 @@ impl FighterStateImpl for DashState {
         &mut self,
         state_context: &mut CollisionContext,
     ) -> Option<FighterState> {
-        ground::collision_interrupt(state_context, &mut self.ground_common, true)
+        ground::collision_interrupt(state_context, true)
     }
 
-    fn is_visually_grounded<'a>(
+    fn is_visually_grounded<'a>(&'a self) -> bool {
-        &'a self,
-    ) -> bool {
         true
     }
 }
@@ -126,10 +115,6 @@ fn check_smash_input_with_dir(state_context: &InterruptContext) -> Option<Fighte
     }
 }
 
-pub fn check_input(
+pub fn check_input(state_context: &InterruptContext) -> Option<FighterState> {
-    state_context: &InterruptContext,
+    check_smash_input_with_dir(state_context).map(|dir| FighterState::Dash(DashState::new(dir)))
-    ground_common: &GroundedStateCommon,
-) -> Option<FighterState> {
-    check_smash_input_with_dir(state_context)
-        .map(|dir| FighterState::Dash(DashState::new(dir, ground_common.clone())))
 }

src/fighter/state/fall.rs

@@ -46,5 +46,8 @@ impl FighterStateImpl for FallState {
     ) -> bool {
         false
     }
-}
 
+    fn surface_policy(&self) -> super::SurfacePolicy {
+        super::SurfacePolicy::Airborne(crate::fighter::surface::EcbLockPolicy::StartOnDetach)
+    }
+}

src/fighter/state/ground.rs

@@ -3,7 +3,7 @@
 //! bit-for-bit deterministic for rollback.
 
 use crate::fighter::state::{
-    CollisionContext, FighterState, InterruptContext, air, dash, fall, ground_attack, turn, wait, walk,
+    CollisionContext, FighterState, InterruptContext, air, crouch, dash, fall, ground_attack, turn, wait, walk,
 };
 use crate::fighter::{
     FighterAttributes, FighterPreviousTranslation, FighterTranslation, FighterVelocity,
@@ -13,13 +13,6 @@ use crate::math::int::{FGWide, FGi32};
 use crate::math::vec::FGVec2;
 use crate::stage::line::{StageLineID, StagePoly, StagePolyLineSegment, StagePolyLineSegmentType};
 
-use bevy::prelude::*;
-
-#[derive(Reflect, Hash, Clone, Debug)]
-pub struct GroundedStateCommon {
-    pub current_line_id: StageLineID,
-}
-
 pub fn apply_grounded_friction(friction: FGi32, ground_vel: FGi32) -> FGi32 {
     if friction.abs() > ground_vel.abs() {
         -ground_vel
@@ -181,22 +174,23 @@ pub fn update_friction_motion(ctx: &mut crate::fighter::state::UpdateContext) {
 
 pub fn collide_with_stage_grounded(
     state_context: &mut CollisionContext,
-    ground_common: &mut GroundedStateCommon,
     can_walk_off: bool,
 ) -> GroundedMotionResult {
     let translation = &mut state_context.translation;
-    let ecb = state_context.ecb;
+    let ecb = &state_context.ecb;
     let stage_collision = state_context.stage_collision;
 
-    let stage_poly = stage_collision
+    let Some(current_line_id) = state_context.surface.line_id() else {
-        .stage_polys
+        return GroundedMotionResult::InAir;
-        .get(ground_common.current_line_id.polygon);
+    };
+
+    let stage_poly = stage_collision.stage_polys.get(current_line_id.polygon);
 
     if let Some(stage_poly) = stage_poly {
         let ecb_bottom_pos = translation.0 + ecb.get_bottom_point();
         match resolve_grounded_position(
             stage_poly,
-            ground_common.current_line_id.segment,
+            current_line_id.segment,
             ecb_bottom_pos,
             can_walk_off,
         ) {
@@ -216,31 +210,45 @@ pub fn collide_with_stage_grounded(
                             .0
                             .project_onto_normalized(current_segment.normal)
                 };
-                ground_common.current_line_id.segment = segment_idx;
+                state_context.surface.land(StageLineID {
+                    polygon: current_line_id.polygon,
+                    segment: segment_idx,
+                });
                 GroundedMotionResult::InGround
             }
-            GroundedPositionResult::InAir => GroundedMotionResult::InAir,
+            GroundedPositionResult::InAir => {
+                state_context.surface.apply_airborne_policy(
+                    crate::fighter::surface::EcbLockPolicy::StartOnDetach,
+                    state_context.leave_ground_ecb_lock_duration,
+                );
+                GroundedMotionResult::InAir
+            }
         }
     } else {
+        state_context.surface.apply_airborne_policy(
+            crate::fighter::surface::EcbLockPolicy::StartOnDetach,
+            state_context.leave_ground_ecb_lock_duration,
+        );
         GroundedMotionResult::InAir
     }
 }
 
-pub fn collision_interrupt(
+pub fn collision_interrupt(ctx: &mut CollisionContext, can_walk_off: bool) -> Option<FighterState> {
-    ctx: &mut CollisionContext,
+    match collide_with_stage_grounded(ctx, can_walk_off) {
-    common: &mut GroundedStateCommon,
-    can_walk_off: bool,
-) -> Option<FighterState> {
-    match collide_with_stage_grounded(ctx, common, can_walk_off) {
         GroundedMotionResult::InGround => None,
-        GroundedMotionResult::InAir => Some(FighterState::Fall(fall::FallState::new(air::AirborneStateCommon::default()))),
+        GroundedMotionResult::InAir => Some(FighterState::Fall(fall::FallState::new(
+            air::AirborneStateCommon::default(),
+        ))),
     }
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::fighter::ecb::FighterPreviousECB;
+    use crate::fighter::{FighterECB, FighterSurfaceState};
     use crate::stage::line::StagePolyType;
+    use crate::input::FighterInput;
 
     fn two_segment_floor() -> StagePoly {
         StagePoly::build(
@@ -346,28 +354,122 @@ mod tests {
             GroundedPositionResult::InAir
         ));
     }
+
+    #[test]
+    fn grounded_collision_updates_surface_segment() {
+        let stage_collision = crate::stage::line::StageCollision {
+            stage_polys: vec![two_segment_floor()],
+        };
+        let mut surface = FighterSurfaceState::Grounded {
+            line_id: StageLineID {
+                polygon: 0,
+                segment: 0,
+            },
+        };
+        let mut translation = FighterTranslation(FGVec2::lit("11", "0"));
+        let previous_translation = FighterPreviousTranslation(translation.0);
+        let mut velocity = FighterVelocity::default();
+        let mut ecb = FighterECB {
+            bottom: FGVec2::lit("0.0", "-0.5"),
+            top: FGVec2::lit("0.0", "0.5"),
+            left: FGVec2::lit("-0.5", "0.0"),
+            right: FGVec2::lit("0.5", "0.0"),
+        };
+        let previous_ecb = FighterPreviousECB::from(ecb);
+        let mut context = CollisionContext {
+            translation: &mut translation,
+            prev_translation: &previous_translation,
+            input: &FighterInput::default(),
+            velocity: &mut velocity,
+            surface: &mut surface,
+            ecb: &mut ecb,
+            prev_ecb: &previous_ecb,
+            stage_collision: &stage_collision,
+            leave_ground_ecb_lock_duration: 10,
+            downward_stick_threshold: FGi32::ONE,
+        };
+
+        assert!(matches!(
+            collide_with_stage_grounded(&mut context, true),
+            GroundedMotionResult::InGround
+        ));
+        assert_eq!(
+            surface.line_id(),
+            Some(StageLineID {
+                polygon: 0,
+                segment: 1,
+            })
+        );
+    }
+
+    #[test]
+    fn walking_off_edge_clears_surface_contact() {
+        let stage_collision = crate::stage::line::StageCollision {
+            stage_polys: vec![StagePoly::build(
+                StagePolyType::Platform,
+                &[
+                    (FGVec2::lit("0", "0"), StagePolyLineSegmentType::Floor),
+                    (FGVec2::lit("10", "0"), StagePolyLineSegmentType::Floor),
+                ],
+            )],
+        };
+        let mut surface = FighterSurfaceState::Grounded {
+            line_id: StageLineID {
+                polygon: 0,
+                segment: 0,
+            },
+        };
+        let mut translation = FighterTranslation(FGVec2::lit("11", "0"));
+        let previous_translation = FighterPreviousTranslation(translation.0);
+        let mut velocity = FighterVelocity::default();
+        let mut ecb = FighterECB {
+            bottom: FGVec2::lit("0.0", "-0.5"),
+            top: FGVec2::lit("0.0", "0.5"),
+            left: FGVec2::lit("-0.5", "0.0"),
+            right: FGVec2::lit("0.5", "0.0"),
+        };
+        let previous_ecb = FighterPreviousECB::from(ecb);
+        let mut context = CollisionContext {
+            translation: &mut translation,
+            prev_translation: &previous_translation,
+            input: &FighterInput::default(),
+            velocity: &mut velocity,
+            surface: &mut surface,
+            ecb: &mut ecb,
+            prev_ecb: &previous_ecb,
+            stage_collision: &stage_collision,
+            leave_ground_ecb_lock_duration: 10,
+            downward_stick_threshold: FGi32::ONE,
+        };
+
+        assert!(matches!(
+            collide_with_stage_grounded(&mut context, true),
+            GroundedMotionResult::InAir
+        ));
+        assert!(matches!(surface, FighterSurfaceState::Airborne { .. }));
+    }
 }
 
 pub fn grounded_movement_common_interrupts(
     state_context: &InterruptContext,
-    ground_common: &GroundedStateCommon,
 ) -> Option<FighterState> {
-    super::jump::check_input(state_context, ground_common)
+    super::jump::check_input(state_context)
 }
 
 pub fn grounded_movement_standstill_common_interrupts(
     state_context: &InterruptContext,
-    ground_common: &GroundedStateCommon,
 ) -> Option<FighterState> {
-    if let Some(state) = ground_attack::check_interrupt(state_context, &ground_common) {
+    if let Some(state) = ground_attack::check_interrupt(state_context) {
         Some(state)
-    } else if let Some(state) = dash::check_input(state_context, &ground_common) {
+    } else if let Some(state) = dash::check_input(state_context) {
         Some(state)
-    } else if let Some(state) = turn::check_input(state_context, &ground_common) {
+    } else if let Some(state) = turn::check_input(state_context) {
         Some(state)
-    } else if let Some(state) = walk::check_input(state_context, &ground_common) {
+    } else if let Some(state) = crouch::check_input(state_context) {
         Some(state)
-    } else if let Some(state) = wait::check_input(state_context, &ground_common) {
+    } else if let Some(state) = walk::check_input(state_context) {
+        Some(state)
+    } else if let Some(state) = wait::check_input(state_context) {
         Some(state)
     } else {
         None

src/fighter/state/ground_attack.rs

@@ -2,14 +2,13 @@ use crate::fighter::{
     attack::{AttackKind, update_active_hitbox_list},
     state::{
         CollisionContext, EnterContext, ExitContext, FighterState, FighterStateImpl,
-        InterruptContext, UpdateContext, ground::GroundedStateCommon, wait::WaitState,
+        InterruptContext, UpdateContext, wait::WaitState,
     },
 };
 
 #[derive(Clone, Debug, Hash)]
 pub struct GroundAttackState {
     pub attack_kind: AttackKind,
-    pub grounded_common: GroundedStateCommon,
 }
 
 impl FighterStateImpl for GroundAttackState {
@@ -17,9 +16,7 @@ impl FighterStateImpl for GroundAttackState {
 
     fn check_interrupt(&self, state_context: &mut InterruptContext) -> Option<FighterState> {
         if state_context.is_current_animation_finished() {
-            Some(FighterState::Wait(WaitState {
+            Some(FighterState::Wait(WaitState))
-                grounded_common: self.grounded_common.clone(),
-            }))
         } else {
             None
         }
@@ -53,7 +50,7 @@ impl FighterStateImpl for GroundAttackState {
             active_hitboxes: Vec::new(),
             solved_hitboxes: Vec::new(),
             hit_fighters: Vec::new(),
-            stalled: false
+            stalled: false,
         });
     }
 
@@ -68,17 +65,12 @@ impl FighterStateImpl for GroundAttackState {
         None
     }
 
-    fn is_visually_grounded<'a>(
+    fn is_visually_grounded<'a>(&'a self) -> bool {
-        &'a self,
-    ) -> bool {
         true
     }
 }
 
-pub fn check_interrupt(
+pub fn check_interrupt(state_context: &InterruptContext) -> Option<FighterState> {
-    state_context: &InterruptContext,
-    grounded_common: &GroundedStateCommon,
-) -> Option<FighterState> {
     if state_context
         .input
         .has_command(crate::input::FighterCommands::Attack)
@@ -89,7 +81,6 @@ pub fn check_interrupt(
             .to_attack_kind_grounded();
         Some(FighterState::GroundAttack(GroundAttackState {
             attack_kind,
-            grounded_common: grounded_common.clone(),
         }))
     } else {
         None

src/fighter/state/hitstun.rs

@@ -7,7 +7,7 @@ use crate::{
             InterruptContext, UpdateContext,
             air::{self, AirborneStateCommon},
             fall::FallState,
-            ground::{GroundedStateCommon, collision_interrupt},
+            ground::collision_interrupt,
             land::LandingType,
             wait::WaitState,
         },
@@ -17,7 +17,7 @@ use crate::{
 
 #[derive(Clone, Debug, Hash)]
 pub enum HitstopStateKind {
-    Grounded(GroundedStateCommon),
+    Grounded,
     Airborne,
 }
 
@@ -43,7 +43,7 @@ impl FighterStateImpl for HitstunState {
 
     fn name(&self) -> String {
         let hitstop_kind = match self.hitstop_kind {
-            HitstopStateKind::Grounded(_) => "Grounded",
+            HitstopStateKind::Grounded => "Grounded",
             HitstopStateKind::Airborne => "Airborne",
         };
 
@@ -58,14 +58,10 @@ impl FighterStateImpl for HitstunState {
     fn check_interrupt(&self, state_context: &mut InterruptContext) -> Option<FighterState> {
         if state_context.get_current_animation_frame() > self.hit_reaction.hitstun_frames {
             match &self.hitstop_kind {
-                HitstopStateKind::Grounded(grounded_state_common) => {
+                HitstopStateKind::Grounded => Some(FighterState::Wait(WaitState)),
-                    Some(FighterState::Wait(WaitState {
+                HitstopStateKind::Airborne => Some(FighterState::Fall(FallState::new(
-                        grounded_common: grounded_state_common.clone(),
+                    AirborneStateCommon::default(),
-                    }))
+                ))),
-                }
-                HitstopStateKind::Airborne => {
-                    Some(FighterState::Fall(FallState::new(AirborneStateCommon::default())))
-                }
             }
         } else {
             None
@@ -85,7 +81,7 @@ impl FighterStateImpl for HitstunState {
         }
 
         match self.hitstop_kind {
-            HitstopStateKind::Grounded(_) => {}
+            HitstopStateKind::Grounded => {}
             HitstopStateKind::Airborne => {
                 air::integrate_gravity(ctx.velocity, ctx.fighter_attributes, false);
             }
@@ -103,7 +99,7 @@ impl FighterStateImpl for HitstunState {
 
     fn on_enter(&mut self, state_context: &mut EnterContext) {
         let animation = match self.hitstop_kind {
-            HitstopStateKind::Grounded(_) => AnimKind::FlinchGround,
+            HitstopStateKind::Grounded => AnimKind::FlinchGround,
             HitstopStateKind::Airborne => AnimKind::FlinchAir,
         };
         state_context.play_animation(animation, false);
@@ -116,9 +112,7 @@ impl FighterStateImpl for HitstunState {
         state_context: &mut CollisionContext,
     ) -> Option<FighterState> {
         match &mut self.hitstop_kind {
-            HitstopStateKind::Grounded(grounded_state_common) => {
+            HitstopStateKind::Grounded => collision_interrupt(state_context, true),
-                collision_interrupt(state_context, grounded_state_common, true)
-            }
             HitstopStateKind::Airborne => {
                 air::collision_interrupt(state_context, LandingType::Normal)
             }
@@ -127,8 +121,17 @@ impl FighterStateImpl for HitstunState {
 
     fn is_visually_grounded<'a>(&'a self) -> bool {
         match self.hitstop_kind {
-            HitstopStateKind::Grounded(_) => true,
+            HitstopStateKind::Grounded => true,
             HitstopStateKind::Airborne => false,
         }
     }
+
+    fn surface_policy(&self) -> super::SurfacePolicy {
+        match self.hitstop_kind {
+            HitstopStateKind::Grounded => super::SurfacePolicy::Grounded,
+            HitstopStateKind::Airborne => super::SurfacePolicy::Airborne(
+                crate::fighter::surface::EcbLockPolicy::StartOnDetach,
+            ),
+        }
+    }
 }

src/fighter/state/jump.rs

@@ -2,10 +2,17 @@ use bevy::prelude::*;
 
 use crate::{
     fighter::{
-        animation::AnimKind, state::{
+        animation::AnimKind,
-            CollisionContext, EnterContext, FighterState, FighterStateImpl, InterruptContext, UpdateContext, air::{self, AirborneStateCommon}, air_dodge::{self, AirDodgeState}, ground::{self, GroundedStateCommon},
+        state::{
+            CollisionContext, EnterContext, FighterState, FighterStateImpl, InterruptContext,
+            UpdateContext,
+            air::{self, AirborneStateCommon},
+            air_dodge::{self, AirDodgeState},
+            ground,
         },
-    }, input::FighterCommands, math::{int::FGi32, vec::FGVec2},
+    },
+    input::FighterCommands,
+    math::{int::FGi32, vec::FGVec2},
 };
 #[derive(Debug, Hash, Clone, Copy)]
 pub enum JumpType {
@@ -22,14 +29,12 @@ pub struct JumpState {
 
 #[derive(Debug, Clone, Hash)]
 pub struct JumpSquatState {
-    pub grounded_common: GroundedStateCommon,
     pub duration_counter: u32,
 }
 
 impl JumpSquatState {
-    pub fn create(grounded_common: GroundedStateCommon) -> Self {
+    pub fn create() -> Self {
         Self {
-            grounded_common,
             duration_counter: 0,
         }
     }
@@ -69,7 +74,10 @@ impl FighterStateImpl for JumpSquatState {
             } else {
                 JumpType::ShortHop
             };
-            Some(FighterState::Jump(JumpState { jump_type, airborne_state_common: AirborneStateCommon::default() }))
+            Some(FighterState::Jump(JumpState {
+                jump_type,
+                airborne_state_common: AirborneStateCommon::default(),
+            }))
         } else {
             None
         }
@@ -84,7 +92,7 @@ impl FighterStateImpl for JumpSquatState {
         &mut self,
         state_context: &mut CollisionContext,
     ) -> Option<FighterState> {
-        ground::collision_interrupt(state_context, &mut self.grounded_common, false)
+        ground::collision_interrupt(state_context, false)
     }
 
     fn on_enter(&mut self, state_context: &mut EnterContext) {
@@ -92,9 +100,7 @@ impl FighterStateImpl for JumpSquatState {
         state_context.input.clear_command(FighterCommands::Jump);
     }
 
-    fn is_visually_grounded<'a>(
+    fn is_visually_grounded<'a>(&'a self) -> bool {
-        &'a self,
-    ) -> bool {
         true
     }
 }
@@ -105,7 +111,7 @@ impl FighterStateImpl for JumpState {
         if state_context.input.has_command(FighterCommands::Jump) {
             Some(FighterState::Jump(JumpState {
                 jump_type: JumpType::DoubleJump,
-                airborne_state_common: AirborneStateCommon::default()
+                airborne_state_common: AirborneStateCommon::default(),
             }))
         } else {
             air_dodge::check_input(state_context)
@@ -177,21 +183,26 @@ impl FighterStateImpl for JumpState {
         )
     }
 
-    fn is_visually_grounded<'a>(
+    fn is_visually_grounded<'a>(&'a self) -> bool {
-        &'a self,
-    ) -> bool {
         false
     }
+
+    fn surface_policy(&self) -> super::SurfacePolicy {
+        use crate::fighter::surface::EcbLockPolicy;
+        match self.jump_type {
+            JumpType::DoubleJump => super::SurfacePolicy::Airborne(EcbLockPolicy::Restart),
+            JumpType::ShortHop | JumpType::LongJump => {
+                super::SurfacePolicy::Airborne(EcbLockPolicy::StartOnDetach)
+            }
+        }
+    }
 }
 
-pub fn check_input(
+pub fn check_input(state_context: &InterruptContext) -> Option<FighterState> {
-    state_context: &InterruptContext,
-    ground_common: &GroundedStateCommon,
-) -> Option<FighterState> {
     state_context
         .input
         .has_command(FighterCommands::Jump)
-        .then(|| FighterState::JumpSquat(JumpSquatState::create(ground_common.clone())))
+        .then(|| FighterState::JumpSquat(JumpSquatState::create()))
 }
 
 pub fn check_input_double_jump(state_context: &InterruptContext) -> Option<FighterState> {
@@ -201,7 +212,7 @@ pub fn check_input_double_jump(state_context: &InterruptContext) -> Option<Fight
         .then(|| {
             FighterState::Jump(JumpState {
                 jump_type: JumpType::DoubleJump,
-                airborne_state_common: AirborneStateCommon::default()
+                airborne_state_common: AirborneStateCommon::default(),
             })
         })
 }

src/fighter/state/land.rs

@@ -3,7 +3,7 @@ use crate::fighter::{
     state::{
         CollisionContext, EnterContext, FighterState, FighterStateImpl, InterruptContext,
         UpdateContext, dash,
-        ground::{self, GroundedStateCommon, grounded_movement_standstill_common_interrupts},
+        ground::{self, grounded_movement_standstill_common_interrupts},
         walk,
     },
 };
@@ -16,16 +16,12 @@ pub enum LandingType {
 
 #[derive(Debug, Clone, Hash)]
 pub struct LandingState {
-    pub grounded_common: GroundedStateCommon,
     pub landing_type: LandingType,
 }
 
 impl LandingState {
-    pub fn create(grounded_common: GroundedStateCommon, landing_type: LandingType) -> Self {
+    pub fn create(landing_type: LandingType) -> Self {
-        Self {
+        Self { landing_type }
-            grounded_common,
-            landing_type,
-        }
     }
 }
 
@@ -34,14 +30,14 @@ impl FighterStateImpl for LandingState {
 
     fn check_interrupt(&self, state_context: &mut InterruptContext) -> Option<FighterState> {
         if state_context.is_current_animation_finished() {
-            grounded_movement_standstill_common_interrupts(state_context, &self.grounded_common)
+            grounded_movement_standstill_common_interrupts(state_context)
         } else if state_context.get_current_animation_frame()
             >= state_context.fighter_attributes.landing_iasa
             && let LandingType::Normal = self.landing_type
         {
-            dash::check_input(state_context, &self.grounded_common).or_else(|| {
+            dash::check_input(state_context).or_else(|| {
-                ground::grounded_movement_common_interrupts(state_context, &self.grounded_common)
+                ground::grounded_movement_common_interrupts(state_context)
-                    .or_else(|| walk::check_input(state_context, &self.grounded_common))
+                    .or_else(|| walk::check_input(state_context))
             })
         } else {
             None
@@ -56,7 +52,7 @@ impl FighterStateImpl for LandingState {
         &mut self,
         state_context: &mut CollisionContext,
     ) -> Option<FighterState> {
-        ground::collision_interrupt(state_context, &mut self.grounded_common, true)
+        ground::collision_interrupt(state_context, true)
     }
 
     fn on_enter(&mut self, state_context: &mut EnterContext) {
@@ -70,9 +66,7 @@ impl FighterStateImpl for LandingState {
         };
     }
 
-    fn is_visually_grounded<'a>(
+    fn is_visually_grounded<'a>(&'a self) -> bool {
-        &'a self,
-    ) -> bool {
         true
     }
 }

src/fighter/state/mod.rs

@@ -7,7 +7,8 @@ use bevy::prelude::*;
 
 use crate::fighter::animation::{AnimKind, FighterAnimationFrame};
 use crate::fighter::attack::{
-    FighterAttackScriptAssets, FighterKnockbackVelocity, FighterPendingHitReaction, FighterStaleMoveQueue, HitStop,
+    FighterAttackScriptAssets, FighterKnockbackVelocity, FighterPendingHitReaction,
+    FighterStaleMoveQueue, HitStop,
 };
 use crate::fighter::attributes::FighterAttributes;
 use crate::fighter::baked_animation::BakedFighterAnimations;
@@ -16,8 +17,11 @@ use crate::fighter::manifest::FighterManifest;
 use crate::fighter::state::hitstun::HitstunState;
 use crate::fighter::visual::FighterAnimations;
 use crate::fighter::{
-    Fighter, FighterECB, FighterFacingDirection, FighterHitboxes, FighterHitstop, FighterHitstopShake, FighterHitstopShakeKind, FighterHitstopShakeRole, FighterPreviousTranslation, FighterTranslation, FighterVelocity,
+    Fighter, FighterECB, FighterFacingDirection, FighterHitboxes, FighterHitstop,
+    FighterHitstopShake, FighterHitstopShakeKind, FighterHitstopShakeRole,
+    FighterPreviousTranslation, FighterSurfaceState, FighterTranslation, FighterVelocity,
 };
+use crate::fighter::surface::EcbLockPolicy;
 use crate::game_settings::GameSettings;
 use crate::input::FighterInput;
 use crate::math::int::FGi32;
@@ -37,6 +41,14 @@ pub mod run;
 pub mod turn;
 pub mod wait;
 pub mod walk;
+pub mod crouch;
+pub mod platform_pass;
+
+#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq)]
+pub enum SurfacePolicy {
+    Grounded,
+    Airborne(EcbLockPolicy),
+}
 
 macro_rules! fighter_states {
     ($($variant:ident => $ty:ty),* $(,)?) => {
@@ -69,6 +81,10 @@ macro_rules! fighter_states {
             pub fn is_visually_grounded(&self) -> bool {
                 match self { $(Self::$variant(s) => s.is_visually_grounded()),* }
             }
+
+            pub fn surface_policy(&self) -> SurfacePolicy {
+                match self { $(Self::$variant(s) => s.surface_policy()),* }
+            }
         }
 
         $(impl From<$ty> for FighterState {
@@ -95,9 +111,11 @@ pub trait FighterStateImpl: Sized {
         None
     }
 
-    fn is_visually_grounded<'a>(
+    fn is_visually_grounded<'a>(&'a self) -> bool;
-        &'a self,
+
-    ) -> bool;
+    fn surface_policy(&self) -> SurfacePolicy {
+        SurfacePolicy::Grounded
+    }
 }
 
 pub struct AnimationStatus {
@@ -110,7 +128,9 @@ pub struct InterruptContext<'a> {
     pub facing_direction: &'a mut FighterFacingDirection,
     pub game_settings: &'a GameSettings,
     pub fighter_attributes: &'a FighterAttributes,
+    pub surface: &'a FighterSurfaceState,
     pub animation: AnimationStatus,
+    pub stage_collision: &'a StageCollision,
 }
 
 impl InterruptContext<'_> {
@@ -131,8 +151,10 @@ pub struct EnterContext<'a> {
     pub stale_move_queue: &'a mut FighterStaleMoveQueue,
     pub facing_direction: &'a mut FighterFacingDirection,
     pub animation_frame: &'a mut FighterAnimationFrame,
+    pub surface: &'a mut FighterSurfaceState,
     pub fighter_attributes: &'a FighterAttributes,
     pub attack_script_assets: &'a FighterAttackScriptAssets,
+    pub game_settings: &'a GameSettings,
 }
 
 impl EnterContext<'_> {
@@ -143,6 +165,7 @@ impl EnterContext<'_> {
 
 pub struct ExitContext<'a> {
     pub hitboxes: &'a mut FighterHitboxes,
+    pub surface: &'a mut FighterSurfaceState,
 }
 
 pub struct UpdateContext<'a> {
@@ -151,6 +174,7 @@ pub struct UpdateContext<'a> {
     pub input: &'a mut FighterInput,
     pub hitboxes: &'a mut FighterHitboxes,
     pub velocity: &'a mut FighterVelocity,
+    pub surface: &'a mut FighterSurfaceState,
     pub knockback_velocity: &'a mut FighterKnockbackVelocity,
     pub game_settings: &'a GameSettings,
     pub animation_frame: u32,
@@ -169,22 +193,31 @@ impl UpdateContext<'_> {
 pub struct CollisionContext<'a> {
     pub translation: &'a mut FighterTranslation,
     pub prev_translation: &'a FighterPreviousTranslation,
+    pub input: &'a FighterInput,
     pub velocity: &'a mut FighterVelocity,
-    pub ecb: &'a FighterECB,
+    pub surface: &'a mut FighterSurfaceState,
+    pub ecb: &'a mut FighterECB,
     pub prev_ecb: &'a FighterPreviousECB,
     pub stage_collision: &'a StageCollision,
+    pub leave_ground_ecb_lock_duration: u32,
+    pub downward_stick_threshold: FGi32,
 }
 
 impl CollisionContext<'_> {
     pub fn air_collide_with_stage(
         &self,
     ) -> Option<crate::fighter::collision::AirCollisionWithStageResult> {
+        let ignored_polys = self.surface.ignored_polygon_ids();
+        let ignore_soft_platforms = self.input.get_last_frame().movement.y
+            <= -self.downward_stick_threshold;
         crate::fighter::collision::air_collide_with_stage(
             self.prev_translation,
             self.translation,
             self.prev_ecb,
             self.ecb,
             self.stage_collision,
+            &ignored_polys,
+            ignore_soft_platforms,
         )
     }
 }
@@ -192,6 +225,8 @@ impl CollisionContext<'_> {
 fighter_states! {
     Wait => wait::WaitState,
     Walk => walk::WalkState,
+    PlatformPass => platform_pass::PlatformPassState,
+    Crouch => crouch::CrouchState,
     Dash => dash::DashState,
     Run => run::RunState,
     Fall => fall::FallState,
@@ -212,9 +247,10 @@ pub struct FighterFrameQuery {
     pub input: &'static mut FighterInput,
     pub hitboxes: &'static mut FighterHitboxes,
     pub velocity: &'static mut FighterVelocity,
+    pub surface: &'static mut FighterSurfaceState,
     pub knockback_velocity: &'static mut FighterKnockbackVelocity,
     pub stale_move_queue: &'static mut FighterStaleMoveQueue,
-    pub ecb: &'static FighterECB,
+    pub ecb: &'static mut FighterECB,
     pub prev_ecb: &'static FighterPreviousECB,
     pub facing_direction: &'static mut FighterFacingDirection,
     pub animation_frame: &'static mut FighterAnimationFrame,
@@ -244,6 +280,7 @@ impl<'w, 's> FighterFrameQueryItem<'w, 's> {
         animations: &'a FighterAnimations,
         baked_animations: &'a Assets<BakedFighterAnimations>,
         attributes: &'a FighterAttributes,
+        stage_collision: &'a StageCollision,
     ) -> InterruptContext<'a> {
         let animation = self.animation_status(animations, baked_animations);
         InterruptContext {
@@ -252,6 +289,8 @@ impl<'w, 's> FighterFrameQueryItem<'w, 's> {
             game_settings,
             fighter_attributes: attributes,
             animation,
+            surface: &self.surface,
+            stage_collision,
         }
     }
 
@@ -259,6 +298,7 @@ impl<'w, 's> FighterFrameQueryItem<'w, 's> {
         &'a mut self,
         attributes: &'a FighterAttributes,
         attack_script_assets: &'a FighterAttackScriptAssets,
+        game_settings: &'a GameSettings,
     ) -> EnterContext<'a> {
         EnterContext {
             input: &mut self.input,
@@ -268,14 +308,17 @@ impl<'w, 's> FighterFrameQueryItem<'w, 's> {
             stale_move_queue: &mut self.stale_move_queue,
             facing_direction: &mut self.facing_direction,
             animation_frame: &mut self.animation_frame,
+            surface: &mut self.surface,
             fighter_attributes: attributes,
             attack_script_assets,
+            game_settings
         }
     }
 
     fn exit_context(&mut self) -> ExitContext<'_> {
         ExitContext {
             hitboxes: &mut self.hitboxes,
+            surface: &mut self.surface,
         }
     }
 
@@ -292,27 +335,33 @@ impl<'w, 's> FighterFrameQueryItem<'w, 's> {
             input: &mut self.input,
             hitboxes: &mut self.hitboxes,
             velocity: &mut self.velocity,
+            surface: &mut self.surface,
             knockback_velocity: &mut self.knockback_velocity,
             game_settings,
             animation_frame: self.animation_frame.frame,
             fighter_attributes: attributes,
             attack_scripts,
             attack_script_assets,
-            facing_direction: &self.facing_direction
+            facing_direction: &self.facing_direction,
         }
     }
 
     fn collision_context<'a>(
         &'a mut self,
         stage_collision: &'a StageCollision,
+        game_settings: &'a GameSettings,
     ) -> CollisionContext<'a> {
         CollisionContext {
             translation: &mut self.translation,
             prev_translation: &self.prev_translation,
+            input: &self.input,
             velocity: &mut self.velocity,
-            ecb: &self.ecb,
+            surface: &mut self.surface,
+            ecb: &mut self.ecb,
             prev_ecb: &self.prev_ecb,
             stage_collision,
+            leave_ground_ecb_lock_duration: game_settings.fighter_common.leave_ground_ecb_frame_lock_duration,
+            downward_stick_threshold: game_settings.input_common.run_stick_threshold,
         }
     }
 }
@@ -367,12 +416,19 @@ fn transition_state(
     frame: &mut FighterFrameQueryItem,
     attributes: &FighterAttributes,
     attack_script_assets: &FighterAttackScriptAssets,
+    game_settings: &GameSettings,
 ) {
     let old_name = current.name();
     let new_name = next.name();
 
     current.on_exit(&mut frame.exit_context());
-    next.on_enter(&mut frame.enter_context(attributes, attack_script_assets));
+    if let SurfacePolicy::Airborne(lock_policy) = next.surface_policy() {
+        frame.surface.apply_airborne_policy(
+            lock_policy,
+            game_settings.fighter_common.leave_ground_ecb_frame_lock_duration,
+        );
+    }
+    next.on_enter(&mut frame.enter_context(attributes, attack_script_assets, game_settings));
     *current = next;
     info!("{} -> {}", old_name, new_name);
 }
@@ -382,6 +438,7 @@ pub fn state_interrupt_system(
     game_settings: Res<GameSettings>,
     baked_animations: Res<Assets<BakedFighterAnimations>>,
     fighter_manifests: Res<Assets<FighterManifest>>,
+    stage_collision: Res<StageCollision>,
 ) {
     for fighter in &mut query {
         let StatefulFighterQueryItem {
@@ -400,7 +457,9 @@ pub fn state_interrupt_system(
 
         let new_state = if let Some(reaction) = pending_hit_reaction.take() {
             hitstop.remaining_frames = *reaction.hitstop_frames;
-            let shake_frames = reaction.hitstop_frames.calculate_shake_frames(&game_settings);
+            let shake_frames = reaction
+                .hitstop_frames
+                .calculate_shake_frames(&game_settings);
             hitstop_shake.role = FighterHitstopShakeRole::Receiver;
             hitstop_shake.total_frames = shake_frames;
             hitstop_shake.remaining_frames = shake_frames;
@@ -410,34 +469,24 @@ pub fn state_interrupt_system(
                 FighterHitstopShakeKind::Vertical
             };
 
-            let mut hitstop_kind = match &*state {
+            let mut hitstop_kind = if frame.surface.is_grounded() {
-                FighterState::Wait(value) => {
+                hitstun::HitstopStateKind::Grounded
-                    hitstun::HitstopStateKind::Grounded(value.grounded_common.clone())
+            } else {
-                }
+                hitstun::HitstopStateKind::Airborne
-                FighterState::Walk(value) => {
-                    hitstun::HitstopStateKind::Grounded(value.grounded_common.clone())
-                }
-                FighterState::Dash(value) => {
-                    hitstun::HitstopStateKind::Grounded(value.ground_common.clone())
-                }
-                FighterState::Run(value) => {
-                    hitstun::HitstopStateKind::Grounded(value.grounded_common.clone())
-                }
-                FighterState::Turn(value) => {
-                    hitstun::HitstopStateKind::Grounded(value.grounded_common.clone())
-                }
-                FighterState::GroundAttack(value) => {
-                    hitstun::HitstopStateKind::Grounded(value.grounded_common.clone())
-                }
-                _ => hitstun::HitstopStateKind::Airborne,
             };
 
-            if let hitstun::HitstopStateKind::Grounded(_) = hitstop_kind {
+            if let hitstun::HitstopStateKind::Grounded = hitstop_kind {
                 let straight_up_angle = FGi32::lit("90.0");
-                if reaction.hitstop_frames >= HitStop::new(game_settings.fighter_common.tumble_bounce_hitstop_threshold) {
+                if reaction.hitstop_frames
+                    >= HitStop::new(game_settings.fighter_common.tumble_bounce_hitstop_threshold)
+                {
                     hitstop_kind = hitstun::HitstopStateKind::Airborne;
                 // TODO: Use floor normal here
-                } else if reaction.launch_angle.abs_diff(straight_up_angle) < game_settings.fighter_common.attack_ground_to_airborne_transition_vertical_angle_threshold {
+                } else if reaction.launch_angle.abs_diff(straight_up_angle)
+                    < game_settings
+                        .fighter_common
+                        .attack_ground_to_airborne_transition_vertical_angle_threshold
+                {
                     hitstop_kind = hitstun::HitstopStateKind::Airborne;
                 } else {
                     // straight down is 270
@@ -463,6 +512,7 @@ pub fn state_interrupt_system(
                 animations,
                 &baked_animations,
                 &manifest.attributes,
+                &stage_collision
             ))
         };
 
@@ -473,6 +523,7 @@ pub fn state_interrupt_system(
                 &mut frame,
                 &manifest.attributes,
                 attack_script_assets,
+                &game_settings,
             );
         };
     }
@@ -482,6 +533,7 @@ pub fn state_collision_interrupt_system(
     mut query: Query<StatefulFighterQuery>,
     stage_collision: Res<StageCollision>,
     fighter_manifests: Res<Assets<FighterManifest>>,
+    game_settings: Res<GameSettings>,
 ) {
     for fighter in &mut query {
         let StatefulFighterQueryItem {
@@ -500,7 +552,7 @@ pub fn state_collision_interrupt_system(
             .get(&fighter.manifest)
             .expect("Fighter manifest should be valid");
         let new_state =
-            state.check_collision_interrupt(&mut frame.collision_context(&stage_collision));
+            state.check_collision_interrupt(&mut frame.collision_context(&stage_collision, &game_settings));
         if let Some(new_state) = new_state {
             transition_state(
                 &mut state,
@@ -508,6 +560,7 @@ pub fn state_collision_interrupt_system(
                 &mut frame,
                 &manifest.attributes,
                 &attack_script_assets,
+                &game_settings,
             );
         }
     }

src/fighter/state/platform_pass.rs

@@ -0,0 +1,61 @@
+use super::{CollisionContext, EnterContext, FighterStateImpl, InterruptContext, UpdateContext};
+use crate::fighter::animation::AnimKind;
+use crate::fighter::state::air::AirborneStateCommon;
+use crate::fighter::state::{ExitContext, FighterState, air, jump};
+
+#[derive(Debug, Clone, Copy, Hash, Default)]
+pub struct PlatformPassState {
+    airborne_state_common: AirborneStateCommon,
+    ignored_polygon: usize,
+}
+
+impl PlatformPassState {
+    pub fn new(airborne_state_common: AirborneStateCommon, ignored_polygon: usize) -> Self {
+        Self {
+            airborne_state_common,
+            ignored_polygon
+        }
+    }
+}
+
+impl FighterStateImpl for PlatformPassState {
+    const NAME: &'static str = "PlatformPass";
+    
+    fn check_interrupt(&self, state_context: &mut InterruptContext) -> Option<FighterState> {
+        jump::check_input_double_jump(state_context)
+    }
+
+    fn on_enter(&mut self, state_context: &mut EnterContext) {
+        state_context.surface.ignore_polygon(self.ignored_polygon, state_context.game_settings.fighter_common.platform_pass_platform_ignore_duration_frames);
+        state_context.velocity.y = state_context.game_settings.fighter_common.platform_pass_initial_downwards_velocity;
+        state_context.play_animation(AnimKind::PlatformPass, false);
+    }
+
+    fn on_exit(&mut self, state_context: &mut ExitContext) {
+        state_context.surface.clear_polygon_ignore(self.ignored_polygon);
+    }
+
+    fn update(&mut self, state_context: &mut UpdateContext) {
+        air::update_standard_motion(state_context, &mut self.airborne_state_common);
+    }
+
+    fn check_collision_interrupt(
+        &mut self,
+        state_context: &mut CollisionContext,
+    ) -> Option<FighterState> {
+        air::collision_interrupt(
+            state_context,
+            crate::fighter::state::land::LandingType::Normal,
+        )
+    }
+    
+    fn is_visually_grounded<'a>(
+        &'a self,
+    ) -> bool {
+        false
+    }
+
+    fn surface_policy(&self) -> super::SurfacePolicy {
+        super::SurfacePolicy::Airborne(crate::fighter::surface::EcbLockPolicy::StartOnDetach)
+    }
+}

src/fighter/state/run.rs

@@ -6,19 +6,14 @@ use super::{
 };
 use crate::fighter::animation::AnimKind;
 use crate::fighter::state::FighterState;
-use crate::fighter::state::ground::GroundedStateCommon;
 
 #[derive(Component, Debug, Clone, Hash)]
-pub struct RunState {
+pub struct RunState;
-    pub grounded_common: GroundedStateCommon,
-}
 
 impl FighterStateImpl for RunState {
     const NAME: &'static str = "Run";
     fn check_interrupt(&self, state_context: &mut InterruptContext) -> Option<FighterState> {
-        if let Some(state) =
+        if let Some(state) = ground::grounded_movement_common_interrupts(state_context) {
-            ground::grounded_movement_common_interrupts(state_context, &self.grounded_common)
-        {
             return Some(state);
         }
 
@@ -28,8 +23,7 @@ impl FighterStateImpl for RunState {
         {
             None
         } else {
-            walk::check_input(state_context, &self.grounded_common)
+            walk::check_input(state_context).or_else(|| wait::check_input(state_context))
-                .or_else(|| wait::check_input(state_context, &self.grounded_common))
         }
     }
 
@@ -62,26 +56,19 @@ impl FighterStateImpl for RunState {
         &mut self,
         state_context: &mut CollisionContext,
     ) -> Option<FighterState> {
-        ground::collision_interrupt(state_context, &mut self.grounded_common, true)
+        ground::collision_interrupt(state_context, true)
     }
 
-    fn is_visually_grounded<'a>(
+    fn is_visually_grounded<'a>(&'a self) -> bool {
-        &'a self,
-    ) -> bool {
         true
     }
 }
 
-pub fn check_input(
+pub fn check_input(state_context: &InterruptContext) -> Option<FighterState> {
-    state_context: &InterruptContext,
-    ground_state_common: &GroundedStateCommon,
-) -> Option<FighterState> {
     let input_frame = state_context.input.get_last_frame();
     if input_frame.movement.x.abs() >= state_context.game_settings.input_common.run_stick_threshold
     {
-        return Some(FighterState::Run(RunState {
+        return Some(FighterState::Run(RunState));
-            grounded_common: ground_state_common.clone(),
-        }));
     }
     None
 }

src/fighter/state/turn.rs

@@ -1,13 +1,11 @@
 use super::{CollisionContext, EnterContext, FighterStateImpl, InterruptContext, UpdateContext};
 use crate::fighter::animation::AnimKind;
-use crate::fighter::state::ground::{self, GroundedStateCommon};
+use crate::fighter::state::ground;
 use crate::fighter::state::{FighterState, dash, jump, wait, walk};
 use crate::input::FighterCommands;
 
 #[derive(Debug, Clone, Hash)]
-pub struct TurnState {
+pub struct TurnState;
-    pub grounded_common: GroundedStateCommon,
-}
 
 impl FighterStateImpl for TurnState {
     const NAME: &'static str = "Turn";
@@ -19,19 +17,19 @@ impl FighterStateImpl for TurnState {
                 .input_common
                 .turn_into_dashback_window as u32
         {
-            if let Some(state) = dash::check_input(state_context, &self.grounded_common) {
+            if let Some(state) = dash::check_input(state_context) {
                 return Some(state);
             }
         }
-        if let Some(state) = jump::check_input(state_context, &self.grounded_common) {
+        if let Some(state) = jump::check_input(state_context) {
             *state_context.facing_direction = state_context.facing_direction.reverse();
             Some(state)
         } else if state_context.is_current_animation_finished() {
-            if let Some(state) = dash::check_input(state_context, &self.grounded_common) {
+            if let Some(state) = dash::check_input(state_context) {
                 Some(state)
-            } else if let Some(state) = walk::check_input(state_context, &self.grounded_common) {
+            } else if let Some(state) = walk::check_input(state_context) {
                 Some(state)
-            } else if let Some(state) = wait::check_input(state_context, &self.grounded_common) {
+            } else if let Some(state) = wait::check_input(state_context) {
                 Some(state)
             } else {
                 None
@@ -54,20 +52,15 @@ impl FighterStateImpl for TurnState {
         &mut self,
         state_context: &mut CollisionContext,
     ) -> Option<FighterState> {
-        ground::collision_interrupt(state_context, &mut self.grounded_common, false)
+        ground::collision_interrupt(state_context, false)
     }
 
-    fn is_visually_grounded<'a>(
+    fn is_visually_grounded<'a>(&'a self) -> bool {
-        &'a self,
-    ) -> bool {
         true
     }
 }
 
-pub fn check_input(
+pub fn check_input(state_context: &InterruptContext) -> Option<FighterState> {
-    state_context: &InterruptContext,
-    grounded_common: &GroundedStateCommon,
-) -> Option<FighterState> {
     let input_frame = state_context.input.get_last_frame();
 
     let has_smash_input = state_context
@@ -81,9 +74,7 @@ pub fn check_input(
         && input_frame.movement.x.signum() != state_context.facing_direction.to_sign()
         && !has_smash_input
     {
-        return Some(FighterState::Turn(TurnState {
+        return Some(FighterState::Turn(TurnState));
-            grounded_common: grounded_common.clone(),
-        }));
     }
     None
 }

src/fighter/state/wait.rs

@@ -3,24 +3,18 @@ use super::{
 };
 use crate::fighter::animation::AnimKind;
 use crate::fighter::state::FighterState;
-use crate::fighter::state::ground::GroundedStateCommon;
 
 #[derive(Debug, Clone, Hash)]
-pub struct WaitState {
+pub struct WaitState;
-    pub grounded_common: GroundedStateCommon,
-}
 
 impl FighterStateImpl for WaitState {
     const NAME: &'static str = "Wait";
     fn check_interrupt(&self, state_context: &mut InterruptContext) -> Option<FighterState> {
-        if let Some(state) =
+        if let Some(state) = ground::grounded_movement_common_interrupts(state_context) {
-            ground::grounded_movement_common_interrupts(state_context, &self.grounded_common)
-        {
             Some(state)
-        } else if let Some(state) = ground::grounded_movement_standstill_common_interrupts(
+        } else if let Some(state) =
-            state_context,
+            ground::grounded_movement_standstill_common_interrupts(state_context)
-            &self.grounded_common,
+        {
-        ) {
             // Don't transition into yourself
             if let FighterState::Wait(_) = state {
                 None
@@ -44,26 +38,19 @@ impl FighterStateImpl for WaitState {
         &mut self,
         state_context: &mut CollisionContext,
     ) -> Option<FighterState> {
-        ground::collision_interrupt(state_context, &mut self.grounded_common, false)
+        ground::collision_interrupt(state_context, false)
     }
 
-    fn is_visually_grounded<'a>(
+    fn is_visually_grounded<'a>(&'a self) -> bool {
-        &'a self,
-    ) -> bool {
         true
     }
 }
 
-pub fn check_input(
+pub fn check_input(state_context: &InterruptContext) -> Option<FighterState> {
-    state_context: &InterruptContext,
-    ground_state_common: &GroundedStateCommon,
-) -> Option<FighterState> {
     let input_frame = state_context.input.get_last_frame();
 
     if input_frame.movement.x.abs() < state_context.game_settings.input_common.stick_deadzone {
-        return Some(FighterState::Wait(WaitState {
+        return Some(FighterState::Wait(WaitState));
-            grounded_common: ground_state_common.clone(),
-        }));
     }
     None
 }

src/fighter/state/walk.rs

@@ -4,23 +4,17 @@ use super::{
 };
 use crate::fighter::animation::AnimKind;
 use crate::fighter::state::FighterState;
-use crate::fighter::state::ground::GroundedStateCommon;
 
 #[derive(Debug, Clone, Hash)]
-pub struct WalkState {
+pub struct WalkState;
-    pub grounded_common: GroundedStateCommon,
-}
 
 impl FighterStateImpl for WalkState {
     const NAME: &'static str = "Walk";
     fn check_interrupt(&self, state_context: &mut InterruptContext) -> Option<FighterState> {
-        if let Some(state) =
+        if let Some(state) = ground::grounded_movement_common_interrupts(state_context) {
-            ground::grounded_movement_common_interrupts(state_context, &self.grounded_common)
-        {
             return Some(state);
         }
-        wait::check_input(state_context, &self.grounded_common)
+        wait::check_input(state_context).or_else(|| dash::check_input(state_context))
-            .or_else(|| dash::check_input(state_context, &self.grounded_common))
     }
 
     fn on_enter(&mut self, state_context: &mut EnterContext) {
@@ -54,26 +48,19 @@ impl FighterStateImpl for WalkState {
         &mut self,
         state_context: &mut CollisionContext,
     ) -> Option<FighterState> {
-        ground::collision_interrupt(state_context, &mut self.grounded_common, false)
+        ground::collision_interrupt(state_context, false)
     }
 
-    fn is_visually_grounded<'a>(
+    fn is_visually_grounded<'a>(&'a self) -> bool {
-        &'a self,
-    ) -> bool {
         true
     }
 }
 
-pub fn check_input(
+pub fn check_input(state_context: &InterruptContext) -> Option<FighterState> {
-    state_context: &InterruptContext,
-    ground_state_common: &GroundedStateCommon,
-) -> Option<FighterState> {
     let input_frame = state_context.input.get_last_frame();
 
     if !input_frame.movement.x.is_zero() {
-        return Some(FighterState::Walk(WalkState {
+        return Some(FighterState::Walk(WalkState));
-            grounded_common: ground_state_common.clone(),
-        }));
     }
 
     None

src/fighter/surface.rs

@@ -0,0 +1,227 @@
+use bevy::prelude::*;
+
+use crate::stage::line::StageLineID;
+
+#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq)]
+pub enum EcbLockPolicy {
+    StartOnDetach,
+    Restart,
+    Preserve,
+    Clear,
+}
+
+/// The stage surface currently supporting a fighter.
+///
+/// This is physics state rather than fighter-state-machine state. Keeping it
+/// separate means grounded, landing, and hitstun states all share one source
+/// of truth for stage contact.
+#[derive(Clone, Debug, Hash, PartialEq, Eq)]
+pub struct IgnoredPolygon {
+    pub polygon: usize,
+    pub frames_remaining: u32,
+}
+
+#[derive(Component, Clone, Debug, Hash, PartialEq, Eq)]
+pub enum FighterSurfaceState {
+    Airborne {
+        ecb_lock_frames_remaining: u32,
+        ignored_polys: Vec<IgnoredPolygon>,
+    },
+    Grounded {
+        line_id: StageLineID,
+    },
+}
+
+impl Default for FighterSurfaceState {
+    fn default() -> Self {
+        Self::Airborne {
+            ecb_lock_frames_remaining: 0,
+            ignored_polys: vec![],
+        }
+    }
+}
+
+impl FighterSurfaceState {
+    pub fn is_grounded(&self) -> bool {
+        matches!(self, Self::Grounded { .. })
+    }
+
+    pub fn line_id(&self) -> Option<StageLineID> {
+        match self {
+            Self::Airborne { .. } => None,
+            Self::Grounded { line_id } => Some(*line_id),
+        }
+    }
+
+    pub(crate) fn land(&mut self, line_id: StageLineID) {
+        *self = Self::Grounded { line_id };
+    }
+
+    pub fn clear_polygon_ignore(&mut self, polygon: usize) {
+        let Self::Airborne { ignored_polys, .. } = self else {
+            return;
+        };
+
+        ignored_polys.retain(|element| element.polygon != polygon);
+    }
+    
+    pub fn ignore_polygon(&mut self, polygon: usize, duration_frames: u32) {
+        let Self::Airborne { ignored_polys, .. } = self else {
+            return;
+        };
+
+        if duration_frames == 0 {
+            return;
+        }
+
+        if let Some(ignored) = ignored_polys.iter_mut().find(|ignored| ignored.polygon == polygon) {
+            ignored.frames_remaining = duration_frames;
+        } else {
+            ignored_polys.push(IgnoredPolygon {
+                polygon,
+                frames_remaining: duration_frames,
+            });
+        }
+    }
+
+    pub fn is_polygon_ignored(&self, polygon: usize) -> bool {
+        matches!(self, Self::Airborne { ignored_polys, .. }
+            if ignored_polys.iter().any(|ignored| ignored.polygon == polygon))
+    }
+
+    pub(crate) fn ignored_polygon_ids(&self) -> Vec<usize> {
+        match self {
+            Self::Airborne { ignored_polys, .. } => {
+                ignored_polys.iter().map(|ignored| ignored.polygon).collect()
+            }
+            Self::Grounded { .. } => vec![],
+        }
+    }
+
+    pub(crate) fn apply_airborne_policy(
+        &mut self,
+        policy: EcbLockPolicy,
+        ecb_lock_duration: u32,
+    ) {
+        let current_lock = match self {
+            Self::Airborne { ecb_lock_frames_remaining, .. } => *ecb_lock_frames_remaining,
+            Self::Grounded { .. } => 0,
+        };
+        let ecb_lock_frames_remaining = match policy {
+            EcbLockPolicy::StartOnDetach if self.is_grounded() => ecb_lock_duration,
+            EcbLockPolicy::StartOnDetach => current_lock,
+            EcbLockPolicy::Restart => ecb_lock_duration,
+            EcbLockPolicy::Preserve => current_lock,
+            EcbLockPolicy::Clear => 0,
+        };
+        let ignored_polys = match self {
+            Self::Airborne { ignored_polys, .. } => ignored_polys.clone(),
+            Self::Grounded { .. } => vec![],
+        };
+        *self = Self::Airborne { ecb_lock_frames_remaining, ignored_polys };
+    }
+
+    pub(crate) fn tick_ecb_lock(&mut self) {
+        if let Self::Airborne { ecb_lock_frames_remaining, .. } = self {
+            *ecb_lock_frames_remaining = ecb_lock_frames_remaining.saturating_sub(1);
+        }
+    }
+
+    pub(crate) fn tick_ignored_polygons(&mut self) {
+        if let Self::Airborne { ignored_polys, .. } = self {
+            for ignored in ignored_polys.iter_mut() {
+                ignored.frames_remaining = ignored.frames_remaining.saturating_sub(1);
+            }
+            ignored_polys.retain(|ignored| ignored.frames_remaining > 0);
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn contact_lifecycle_has_one_source_of_truth() {
+        let mut surface = FighterSurfaceState::default();
+        assert!(!surface.is_grounded());
+        assert_eq!(surface.line_id(), None);
+
+        let line_id = StageLineID {
+            polygon: 2,
+            segment: 3,
+        };
+        surface.land(line_id);
+        assert!(surface.is_grounded());
+        assert_eq!(surface.line_id(), Some(line_id));
+
+        surface.apply_airborne_policy(EcbLockPolicy::Clear, 0);
+        assert!(!surface.is_grounded());
+        assert_eq!(surface.line_id(), None);
+    }
+
+    #[test]
+    fn start_on_detach_does_not_reset_an_existing_lock() {
+        let mut surface = FighterSurfaceState::default();
+        surface.apply_airborne_policy(EcbLockPolicy::Restart, 5);
+        surface.tick_ecb_lock();
+        surface.apply_airborne_policy(EcbLockPolicy::StartOnDetach, 5);
+
+        assert_eq!(
+            surface,
+            FighterSurfaceState::Airborne {
+                ecb_lock_frames_remaining: 4,
+                ignored_polys: vec![],
+            }
+        );
+    }
+
+    #[test]
+    fn restart_retriggers_an_existing_lock() {
+        let mut surface = FighterSurfaceState::default();
+        surface.apply_airborne_policy(EcbLockPolicy::Restart, 5);
+        surface.tick_ecb_lock();
+        surface.apply_airborne_policy(EcbLockPolicy::Restart, 5);
+
+        assert_eq!(
+            surface,
+            FighterSurfaceState::Airborne {
+                ecb_lock_frames_remaining: 5,
+                ignored_polys: vec![],
+            }
+        );
+    }
+
+    #[test]
+    fn ignored_polygon_expires_after_requested_frames() {
+        let mut surface = FighterSurfaceState::default();
+        surface.ignore_polygon(3, 2);
+
+        assert!(surface.is_polygon_ignored(3));
+        surface.tick_ignored_polygons();
+        assert!(surface.is_polygon_ignored(3));
+        surface.tick_ignored_polygons();
+        assert!(!surface.is_polygon_ignored(3));
+    }
+
+    #[test]
+    fn ignoring_polygon_refreshes_existing_entry() {
+        let mut surface = FighterSurfaceState::default();
+        surface.ignore_polygon(3, 2);
+        surface.ignore_polygon(3, 5);
+        surface.tick_ignored_polygons();
+        surface.tick_ignored_polygons();
+        assert!(surface.is_polygon_ignored(3));
+    }
+
+    #[test]
+    fn airborne_policy_preserves_ignored_polygons_and_landing_clears_them() {
+        let mut surface = FighterSurfaceState::default();
+        surface.ignore_polygon(3, 5);
+        surface.apply_airborne_policy(EcbLockPolicy::Restart, 2);
+        assert!(surface.is_polygon_ignored(3));
+
+        surface.land(StageLineID { polygon: 0, segment: 0 });
+        assert!(!surface.is_polygon_ignored(3));
+    }
+}

src/game_settings.rs

@@ -39,6 +39,9 @@ pub struct FighterSettingsCommon {
     
     /// Maximum angle changed caused by directional influence
     pub di_max_angle: FGi32,
+    pub leave_ground_ecb_frame_lock_duration: u32,
+    pub platform_pass_platform_ignore_duration_frames: u32,
+    pub platform_pass_initial_downwards_velocity: FGi32,
 }
 #[derive(Reflect, Serialize, Deserialize, Clone)]
 #[reflect(opaque)]

src/input/buffer.rs

@@ -233,6 +233,8 @@ pub fn postprocess_input(
             input.clear_command(FighterCommands::SmashMoveUp);
             input.clear_command(FighterCommands::SmashMoveDown);
 
+            input.frames_in_y_flick_deadzone = 0xFF;
+
             let command_to_set = if input.current_frame.movement.y > 0.0 {
                 FighterCommands::SmashMoveUp
             } else {

src/input/gamecube/poll.rs

@@ -1,6 +1,8 @@
 use std::panic::{self, AssertUnwindSafe};
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::{Arc, Mutex};
+use std::thread::JoinHandle;
+use std::time::{Duration, Instant};
 
 use bevy::prelude::*;
 use gc_adapter_neo::{Controller, GcAdapter};
@@ -55,10 +57,11 @@ impl GcPortState {
 /// Shared, `Send + Sync` handle to the latest snapshot from the poll
 /// thread. Safe to store as an ordinary [`Resource`] (no `NonSend` needed)
 /// because the `GcAdapter` itself never leaves its thread.
-#[derive(Resource, Clone)]
+#[derive(Resource)]
 pub struct GcAdapterSnapshot {
     ports: Arc<Mutex<[GcPortState; 4]>>,
     shutdown: Arc<AtomicBool>,
+    poll_thread: Option<JoinHandle<()>>,
 }
 
 impl GcAdapterSnapshot {
@@ -69,13 +72,37 @@ impl GcAdapterSnapshot {
 
 impl Drop for GcAdapterSnapshot {
     fn drop(&mut self) {
-        // Only actually signals shutdown once the last clone (this resource
+        self.shutdown.store(true, Ordering::Release);
-        // is never cloned in practice, but be defensive) is dropped.
+
-        if Arc::strong_count(&self.shutdown) <= 1 {
+        if let Some(poll_thread) = self.poll_thread.take() {
-            self.shutdown.store(true, Ordering::Relaxed);
+            if let Err(payload) = poll_thread.join() {
+                error!(
+                    "GameCube Controller Adapter poll thread panicked during shutdown: {payload:?}"
+                );
             }
         }
     }
+}
+
+const INITIAL_ERROR_BACKOFF: Duration = Duration::from_millis(1);
+const MAX_ERROR_BACKOFF: Duration = Duration::from_millis(100);
+
+fn next_error_backoff(backoff: Duration) -> Duration {
+    backoff.saturating_mul(2).min(MAX_ERROR_BACKOFF)
+}
+
+/// Wait for a retry while still allowing the owner to shut the poll thread down promptly.
+fn wait_for_retry(shutdown: &AtomicBool, delay: Duration) -> bool {
+    let deadline = Instant::now() + delay;
+    while !shutdown.load(Ordering::Acquire) {
+        let remaining = deadline.saturating_duration_since(Instant::now());
+        if remaining.is_zero() {
+            return true;
+        }
+        std::thread::sleep(remaining.min(Duration::from_millis(10)));
+    }
+    false
+}
 
 /// Connects to the first GameCube adapter found on the USB bus and starts
 /// polling it on a dedicated thread. Returns `None` (after logging a
@@ -94,7 +121,7 @@ pub fn spawn_poll_thread() -> Result<GcAdapterSnapshot, gc_adapter_neo::UsbError
 
     let thread_ports = ports.clone();
     let thread_shutdown = shutdown.clone();
-    std::thread::Builder::new()
+    let poll_thread = std::thread::Builder::new()
         .name("gc-adapter-poll".into())
         .spawn(move || {
             // Flush whatever the adapter had buffered before we started
@@ -107,17 +134,27 @@ pub fn spawn_poll_thread() -> Result<GcAdapterSnapshot, gc_adapter_neo::UsbError
             let mut rate_window_start = std::time::Instant::now();
             #[cfg(debug_assertions)]
             let mut rate_window_count: u32 = 0;
+            let mut error_backoff = INITIAL_ERROR_BACKOFF;
 
-            while !thread_shutdown.load(Ordering::Relaxed) {
+            while !thread_shutdown.load(Ordering::Acquire) {
                 let result = panic::catch_unwind(AssertUnwindSafe(|| adapter.read_controllers()));
 
                 let controllers = match result {
-                    Ok(Ok(controllers)) => controllers,
+                    Ok(Ok(controllers)) => {
+                        error_backoff = INITIAL_ERROR_BACKOFF;
+                        controllers
+                    }
                     // Ignore this, for some reason we get a bunch of these when we start reading
                     Ok(Err(
                         gc_adapter_neo::AdapterError::Parse(_)
                         | gc_adapter_neo::AdapterError::ShortRead(_),
-                    )) => continue,
+                    )) => {
+                        if !wait_for_retry(&thread_shutdown, error_backoff) {
+                            break;
+                        }
+                        error_backoff = next_error_backoff(error_backoff);
+                        continue;
+                    }
                     Ok(Err(gc_adapter_neo::AdapterError::Usb(err))) => {
                         error!(
                             "GameCube Controller Adapter USB read failed ({err:?}); stopping \
@@ -160,5 +197,32 @@ pub fn spawn_poll_thread() -> Result<GcAdapterSnapshot, gc_adapter_neo::UsbError
         })
         .expect("failed to spawn gc-adapter poll thread");
 
-    Ok(GcAdapterSnapshot { ports, shutdown })
+    Ok(GcAdapterSnapshot {
+        ports,
+        shutdown,
+        poll_thread: Some(poll_thread),
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn error_backoff_is_capped() {
+        let mut backoff = INITIAL_ERROR_BACKOFF;
+        for _ in 0..16 {
+            backoff = next_error_backoff(backoff);
+        }
+
+        assert_eq!(backoff, MAX_ERROR_BACKOFF);
+        assert_eq!(next_error_backoff(MAX_ERROR_BACKOFF), MAX_ERROR_BACKOFF);
+    }
+
+    #[test]
+    fn retry_wait_stops_when_shutdown_is_requested() {
+        let shutdown = AtomicBool::new(true);
+
+        assert!(!wait_for_retry(&shutdown, Duration::from_secs(1)));
+    }
 }

src/match_loading.rs

@@ -336,6 +336,15 @@ pub fn prepare_match(
             );
             return;
         }
+
+        let ecb_bone_indices = baked.bone_names.iter().enumerate().filter_map(|(idx, name)| {
+            if manifest.ecb_bones.contains(name) {
+                Some(idx)
+            } else {
+                None
+            }
+        }).collect::<Vec<_>>();
+
         if let Err(error) = manifest.attributes.validate() {
             fail_match(
                 &mut next_state,
@@ -436,6 +445,7 @@ pub fn prepare_match(
             attack_scripts,
             manifest_handle,
             manifest.model_scale,
+            ecb_bone_indices,
         ));
     }
 
@@ -477,7 +487,7 @@ pub fn prepare_match(
     );
 
     let mut fighter_roster = Vec::with_capacity(config.players.len());
-    for (index, (player, (scene, animations, attack_scripts, manifest_handle, model_scale))) in
+    for (index, (player, (scene, animations, attack_scripts, manifest_handle, model_scale, ecb_bone_indices))) in
         config.players.iter().zip(prepared).enumerate()
     {
         let spawn_x = (index as i32 * 2 + 1 - config.players.len() as i32) * 5;
@@ -490,6 +500,7 @@ pub fn prepare_match(
             animations,
             attack_scripts,
             WorldAssetRoot(scene),
+            ecb_bone_indices
         ));
     }
 

src/math/vec.rs

@@ -2,7 +2,7 @@ use bevy::math::Vec2;
 use bevy::prelude::*;
 use fixed::types::I32F32;
 use serde::{Deserialize, Serialize};
-use std::ops::{Add, AddAssign, Div, Mul, MulAssign, Sub};
+use std::ops::{Add, AddAssign, Div, Mul, MulAssign, Sub, SubAssign};
 
 use super::int::{FGWide, FGi32};
 
@@ -227,6 +227,15 @@ impl AddAssign for FGVec2 {
     }
 }
 
+impl SubAssign for FGVec2 {
+    fn sub_assign(&mut self, rhs: Self) {
+        *self = Self {
+            x: self.x - rhs.x,
+            y: self.y - rhs.y,
+        }
+    }
+}
+
 impl MulAssign for FGVec2 {
     fn mul_assign(&mut self, rhs: Self) {
         *self = Self {

src/menus/character_select/mod.rs

@@ -1,19 +1,8 @@
 use bevy::{picking::pointer::PointerId, prelude::*};
 
 use crate::{
-    AppState,
+    AppState, fighter::manifest::{FighterManifest, FighterManifestRegistry}, game_settings::CommonAssets, input::{LocalInputAssignments, LocalInputSource}, menus::{
-    fighter::manifest::{FighterManifest, FighterManifestRegistry},
+        MenuCameraMarker, MenuMarker, button::FGUiButton, character_select::{character_box::CharacterBox, token::CharacterSelectToken}, cursor::{FGMenuCursor, MenuCursorInputSource}, errors::MenuErrors::FighterManifestNotFound, match_config::{MenuMatchConfig, MenuMatchPlayerSlot}, scaling, spawn_menu, style::{FGUiButtonType, FGUiStyle},
-    game_settings::CommonAssets,
-    input::{LocalInputAssignments, LocalInputSource},
-    menus::{
-        MenuMarker,
-        button::FGUiButton,
-        character_select::{character_box::CharacterBox, token::CharacterSelectToken},
-        cursor::{FGMenuCursor, MenuCursorInputSource},
-        errors::MenuErrors::FighterManifestNotFound,
-        match_config::{MenuMatchConfig, MenuMatchPlayerSlot},
-        scaling, spawn_menu,
-        style::{FGUiButtonType, FGUiStyle},
     },
 };
 
@@ -241,7 +230,7 @@ pub fn copy_cursor_transform_to_token(
     character_boxes: Query<(&CharacterBox, &ComputedNode, &UiGlobalTransform)>,
     match_config: Res<MenuMatchConfig>,
     cursors: Query<&UiGlobalTransform, With<FGMenuCursor>>,
-    cam: Single<&Camera>,
+    cam: Single<&Camera, With<MenuCameraMarker>>,
     ui_scale: Res<UiScale>,
 ) -> Result {
     let camera = cam.into_inner();

src/menus/cursor.rs

@@ -9,11 +9,8 @@ use bevy::{
 };
 
 use crate::{
-    input::{LocalInputAssignments, LocalInputSource},
+    input::{LocalInputAssignments, LocalInputSource}, menus::{
-    menus::{
+        MenuCameraMarker, input::{MenuInput, MenuInputState}, scaling, style::FGUiStyle,
-        input::{MenuInput, MenuInputState},
-        scaling,
-        style::FGUiStyle,
     },
 };
 
@@ -181,7 +178,7 @@ pub fn cursor_input(
 }
 
 pub fn update_cursor_transform(
-    camera: Single<&Camera>,
+    camera: Single<&Camera, With<MenuCameraMarker>>,
     query: Query<(&mut Node, &PointerLocation), With<FGMenuCursor>>,
     ui_scale: Res<UiScale>,
 ) {

src/menus/mod.rs

@@ -53,6 +53,7 @@ pub fn wrap_menu(menu: impl Scene) -> impl Scene {
                 #MenuCamera
                 Camera
                 Camera2d
+                MenuCameraMarker
             ),
             (
                 #MenuContainer
@@ -73,7 +74,6 @@ pub fn wrap_menu(menu: impl Scene) -> impl Scene {
 
 pub fn despawn_menu(
     existing_menu: Option<Single<Entity, With<MenuMarker>>>,
-    existing_menu_camera: Option<Single<Entity, With<MenuCameraMarker>>>,
     mut commands: Commands,
 ) {
     if let Some(entity) = existing_menu {
@@ -82,9 +82,6 @@ pub fn despawn_menu(
             .despawn();
     }
 
-    if let Some(menu_cam) = existing_menu_camera {
-        commands.entity(*menu_cam).despawn();
-    }
 }
 
 pub fn spawn_menu(

src/schedule.rs

@@ -19,10 +19,10 @@ pub enum GameplaySet {
     StateUpdate,
     /// Integrate velocities into positions.
     Physics,
-    /// Solve collision boxes
-    Animation,
     /// Resolve the integrated positions against the stage.
     Collision,
+    /// Solve collision boxes
+    Animation,
     /// Resolve attacks
     Attacks,
 }
@@ -40,8 +40,8 @@ impl Plugin for GameplaySchedulePlugin {
                 GameplaySet::Interrupt,
                 GameplaySet::StateUpdate,
                 GameplaySet::Physics,
-                GameplaySet::Collision,
                 GameplaySet::Animation,
+                GameplaySet::Collision,
                 GameplaySet::Attacks,
             )
                 .chain(),

src/stage/line.rs

@@ -26,7 +26,7 @@ pub enum StagePolyType {
     Platform,
 }
 
-#[derive(Reflect, Hash, Debug, Clone, Copy, Default)]
+#[derive(Reflect, Hash, Debug, Clone, Copy, Default, PartialEq, Eq)]
 pub struct StageLineID {
     pub polygon: usize,
     pub segment: usize,
@@ -34,7 +34,7 @@ pub struct StageLineID {
 
 #[derive(Reflect, Clone, Default)]
 pub struct StagePoly {
-    poly_type: StagePolyType,
+    pub poly_type: StagePolyType,
     pub segments: Vec<StagePolyLineSegment>,
 }