Implement fast falling (#44)

Reviewed-on: #44
Co-authored-by: Álex Román Núñez <eirexe@eirteam.moe>

src/fighter/state/hitstun.rs

@@ -1,14 +1,18 @@
 use crate::{
     fighter::{
-        animation::AnimKind, attack::{self, FighterHitReaction}, state::{
+        animation::AnimKind,
+        attack::{self, FighterHitReaction},
+        state::{
             CollisionContext, EnterContext, ExitContext, FighterState, FighterStateImpl,
-            InterruptContext, UpdateContext, air,
+            InterruptContext, UpdateContext,
+            air::{self, AirborneStateCommon},
             fall::FallState,
             ground::{GroundedStateCommon, collision_interrupt},
             land::LandingType,
             wait::WaitState,
         },
-    }, math::int::FGi32,
+    },
+    math::int::FGi32,
 };
 
 #[derive(Clone, Debug, Hash)]
@@ -21,7 +25,7 @@ pub enum HitstopStateKind {
 pub struct HitstunState {
     pub hit_reaction: FighterHitReaction,
     pub hitstop_kind: HitstopStateKind,
-    knockback_applied: bool
+    knockback_applied: bool,
 }
 
 impl HitstunState {
@@ -29,7 +33,7 @@ impl HitstunState {
         Self {
             hit_reaction,
             hitstop_kind,
-            knockback_applied: false
+            knockback_applied: false,
         }
     }
 }
@@ -59,7 +63,9 @@ impl FighterStateImpl for HitstunState {
                         grounded_common: grounded_state_common.clone(),
                     }))
                 }
-                HitstopStateKind::Airborne => Some(FighterState::Fall(FallState)),
+                HitstopStateKind::Airborne => {
+                    Some(FighterState::Fall(FallState::new(AirborneStateCommon::default())))
+                }
             }
         } else {
             None
@@ -69,16 +75,21 @@ impl FighterStateImpl for HitstunState {
     fn update(&mut self, ctx: &mut UpdateContext) {
         if !self.knockback_applied {
             let launch_direction = attack::directional_influence::apply_directional_influence(
-        ctx.input.get_last_frame().movement,
+                ctx.input.get_last_frame().movement,
                 self.hit_reaction.launch_angle,
-                ctx.game_settings.fighter_common.di_max_angle
+                ctx.game_settings.fighter_common.di_max_angle,
             );
 
             ctx.knockback_velocity.0 = launch_direction * self.hit_reaction.launch_velocity;
             self.knockback_applied = true;
         }
 
-        air::integrate_gravity(ctx.velocity, ctx.fighter_attributes);
+        match self.hitstop_kind {
+            HitstopStateKind::Grounded(_) => {}
+            HitstopStateKind::Airborne => {
+                air::integrate_gravity(ctx.velocity, ctx.fighter_attributes, false);
+            }
+        }
 
         let speed = ctx.knockback_velocity.length();
         let next_speed = speed
@@ -113,10 +124,8 @@ impl FighterStateImpl for HitstunState {
             }
         }
     }
-    
-    fn is_visually_grounded<'a>(
-        &'a self,
-    ) -> bool {
+
+    fn is_visually_grounded<'a>(&'a self) -> bool {
         match self.hitstop_kind {
             HitstopStateKind::Grounded(_) => true,
             HitstopStateKind::Airborne => false,