Add authoritative fighter surface state

src/fighter/state/ground.rs

@@ -3,7 +3,8 @@
 //! 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, dash, fall, ground_attack, turn, wait,
+    walk,
 };
 use crate::fighter::{
     FighterAttributes, FighterPreviousTranslation, FighterTranslation, FighterVelocity,
@@ -13,13 +14,6 @@ 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 +175,23 @@ 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 stage_collision = state_context.stage_collision;
 
-    let stage_poly = stage_collision
-        .stage_polys
-        .get(ground_common.current_line_id.polygon);
+    let Some(current_line_id) = state_context.surface.line_id() else {
+        return GroundedMotionResult::InAir;
+    };
+
+    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,
         ) {
@@ -216,30 +211,37 @@ 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.leave_ground();
+                GroundedMotionResult::InAir
+            }
         }
     } else {
+        state_context.surface.leave_ground();
         GroundedMotionResult::InAir
     }
 }
 
-pub fn collision_interrupt(
-    ctx: &mut CollisionContext,
-    common: &mut GroundedStateCommon,
-    can_walk_off: bool,
-) -> Option<FighterState> {
-    match collide_with_stage_grounded(ctx, common, can_walk_off) {
+pub fn collision_interrupt(ctx: &mut CollisionContext, can_walk_off: bool) -> Option<FighterState> {
+    match collide_with_stage_grounded(ctx, 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;
 
     fn two_segment_floor() -> StagePoly {
@@ -346,28 +348,110 @@ 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 ecb = FighterECB {
+            vertical_half: FGi32::ONE,
+            horizontal_half: FGi32::ONE,
+        };
+        let previous_ecb = FighterPreviousECB::from(ecb);
+        let mut context = CollisionContext {
+            translation: &mut translation,
+            prev_translation: &previous_translation,
+            velocity: &mut velocity,
+            surface: &mut surface,
+            ecb: &ecb,
+            prev_ecb: &previous_ecb,
+            stage_collision: &stage_collision,
+        };
+
+        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 ecb = FighterECB {
+            vertical_half: FGi32::ONE,
+            horizontal_half: FGi32::ONE,
+        };
+        let previous_ecb = FighterPreviousECB::from(ecb);
+        let mut context = CollisionContext {
+            translation: &mut translation,
+            prev_translation: &previous_translation,
+            velocity: &mut velocity,
+            surface: &mut surface,
+            ecb: &ecb,
+            prev_ecb: &previous_ecb,
+            stage_collision: &stage_collision,
+        };
+
+        assert!(matches!(
+            collide_with_stage_grounded(&mut context, true),
+            GroundedMotionResult::InAir
+        ));
+        assert_eq!(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) = walk::check_input(state_context) {
         Some(state)
-    } else if let Some(state) = wait::check_input(state_context, &ground_common) {
+    } else if let Some(state) = wait::check_input(state_context) {
         Some(state)
     } else {
         None