Implement fast falling (#44)

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

assets/fighters/test/test.fighter.ron

@@ -22,7 +22,8 @@
         air_jump_horizontal_velocity: "0.96",
         air_jump_multiplier: "1.0",
         dash_initial_velocity: "1.4",
-        terminal_velocity: "1.6",
+        terminal_velocity: "3.0",
+        fast_fall_speed: "3.5",
         gravity: "0.084",
         weight: "100.0",
         jumpsquat_duration: 5,

src/fighter/attributes.rs

@@ -37,6 +37,7 @@ pub struct FighterAttributes {
     pub ground_friction: FGi32,
     pub terminal_velocity: FGi32,
     pub gravity: FGi32,
+    pub fast_fall_speed: FGi32,
     pub weight: FGi32,
     pub air_friction: FGi32,
 

src/fighter/debug.rs

@@ -412,7 +412,7 @@ pub fn attack_debug_gather(
         points.reserve(hit.hitstun_frames as usize);
 
         for _ in 1..hit.hitstun_frames {
-            air::integrate_gravity(&mut fighter_vel, &manifest.attributes);
+            air::integrate_gravity(&mut fighter_vel, &manifest.attributes, false);
 
             let vel = knockback_vel.length();
             let new_vel = vel

src/fighter/mod.rs

@@ -38,7 +38,7 @@ use crate::{
             AttackKind, FighterAttackPlugin, FighterAttackScriptAssets, FighterDamage,
             FighterKnockbackVelocity, FighterPendingHitReaction, FighterSolvedHurtboxes,
             FighterStaleMoveQueue,
-        }, baked_animation::{FighterBoneIndexMap, FighterBoneMatrices}, manifest::FighterManifest, state::{FighterState, fall::FallState}, visual::FighterAnimations,
+        }, baked_animation::{FighterBoneIndexMap, FighterBoneMatrices}, 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;
@@ -299,7 +299,7 @@ pub fn spawn_fighter(
             visual_root,
             animations,
             attack_scripts,
-            FighterState::Fall(FallState),
+            FighterState::Fall(FallState::new(AirborneStateCommon::default())),
             animation::FighterAnimationFrame::new(animation::AnimKind::Wait, true),
             (
                 baked_animation::FighterBoneMatrices::default(),

src/fighter/state/air.rs

@@ -2,10 +2,44 @@ use crate::fighter::state::ground::GroundedStateCommon;
 use crate::fighter::state::land::{LandingState, LandingType};
 use crate::fighter::state::{CollisionContext, FighterState};
 use crate::fighter::*;
+use crate::input::FighterCommands;
 
-pub fn integrate_gravity(velocity: &mut FighterVelocity, attributes: &FighterAttributes) {
+#[derive(Default, Debug, Clone, Copy, Hash)]
+pub struct AirborneStateCommon {
+    pub is_fast_falling: bool,
+}
+
+pub fn process_fast_fall(
+    airborne_state_common: &mut AirborneStateCommon,
+    input: &mut FighterInput,
+    velocity: &mut FighterVelocity,
+    attributes: &FighterAttributes,
+) {
+    if velocity.y.is_negative() {
+        if input.has_command(FighterCommands::SmashMoveDown) {
+            airborne_state_common.is_fast_falling = true;
+        }
+        input.clear_command(FighterCommands::SmashMoveDown);
+    }
+
+    if airborne_state_common.is_fast_falling {
+        velocity.y = -attributes.fast_fall_speed;
+    }
+}
+
+pub fn integrate_gravity(
+    velocity: &mut FighterVelocity,
+    attributes: &FighterAttributes,
+    fast_fall: bool
+) {
     velocity.y -= attributes.gravity;
-    velocity.y = velocity.y.max(-attributes.terminal_velocity);
+
+    let terminal_vel = if fast_fall {
+        -attributes.fast_fall_speed
+    } else {
+        -attributes.terminal_velocity
+    };
+    velocity.y = velocity.y.max(terminal_vel);
 }
 
 pub fn apply_air_drift(
@@ -56,8 +90,12 @@ pub fn apply_air_motion(
     translation.0 += velocity.0;
 }
 
-pub fn update_standard_motion(ctx: &mut crate::fighter::state::UpdateContext) {
+pub fn update_standard_motion(
-    integrate_gravity(ctx.velocity, ctx.fighter_attributes);
+    ctx: &mut crate::fighter::state::UpdateContext,
+    airborne_common: &mut AirborneStateCommon,
+) {
+    process_fast_fall(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);
 }
@@ -110,6 +148,7 @@ mod tests {
             air_drift_max: FGi32::lit("1.2"),
             ground_friction: FGi32::ZERO,
             terminal_velocity: FGi32::ZERO,
+            fast_fall_speed: FGi32::ZERO,
             gravity: FGi32::ZERO,
             weight: FGi32::lit("1"),
             air_friction: FGi32::lit("0.001"),

src/fighter/state/air_dodge.rs

@@ -1,13 +1,9 @@
 use crate::{
     fighter::{
-        animation::AnimKind,
+        animation::AnimKind, state::{
-        state::{
+            CollisionContext, EnterContext, FighterState, FighterStateImpl, InterruptContext, UpdateContext, air::{self, AirborneStateCommon}, fall::FallState, land::LandingType,
-            CollisionContext, EnterContext, FighterState, FighterStateImpl, InterruptContext,
-            UpdateContext, air, fall::FallState, land::LandingType,
         },
-    },
+    }, input, math::vec::FGVec2,
-    input,
-    math::vec::FGVec2,
 };
 
 #[derive(Debug, Clone, Hash)]
@@ -20,7 +16,7 @@ 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))
+            Some(FighterState::Fall(FallState::new(AirborneStateCommon::default())))
         } else {
             None
         }

src/fighter/state/fall.rs

@@ -1,12 +1,24 @@
 use super::{CollisionContext, EnterContext, FighterStateImpl, InterruptContext, UpdateContext};
 use crate::fighter::animation::AnimKind;
+use crate::fighter::state::air::AirborneStateCommon;
 use crate::fighter::state::{FighterState, air, jump};
 
-#[derive(Debug, Clone, Copy, Hash)]
+#[derive(Debug, Clone, Copy, Hash, Default)]
-pub struct FallState;
+pub struct FallState {
+    airborne_state_common: AirborneStateCommon
+}
+
+impl FallState {
+    pub fn new(airborne_state_common: AirborneStateCommon) -> Self {
+        Self {
+            airborne_state_common
+        }
+    }
+}
 
 impl FighterStateImpl for FallState {
     const NAME: &'static str = "Fall";
+    
     fn check_interrupt(&self, state_context: &mut InterruptContext) -> Option<FighterState> {
         jump::check_input_double_jump(state_context)
     }
@@ -16,7 +28,7 @@ impl FighterStateImpl for FallState {
     }
 
     fn update(&mut self, state_context: &mut UpdateContext) {
-        air::update_standard_motion(state_context);
+        air::update_standard_motion(state_context, &mut self.airborne_state_common);
     }
 
     fn check_collision_interrupt(
@@ -36,11 +48,3 @@ impl FighterStateImpl for FallState {
     }
 }
 
-pub fn check_input(state_context: &InterruptContext) -> 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::Fall(FallState));
-    }
-    None
-}

src/fighter/state/ground.rs

@@ -3,7 +3,7 @@
 //! bit-for-bit deterministic for rollback.
 
 use crate::fighter::state::{
-    CollisionContext, FighterState, InterruptContext, 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,
@@ -233,7 +233,7 @@ pub fn collision_interrupt(
 ) -> Option<FighterState> {
     match collide_with_stage_grounded(ctx, common, can_walk_off) {
         GroundedMotionResult::InGround => None,
-        GroundedMotionResult::InAir => Some(FighterState::Fall(fall::FallState)),
+        GroundedMotionResult::InAir => Some(FighterState::Fall(fall::FallState::new(air::AirborneStateCommon::default()))),
     }
 }
 

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
@@ -114,9 +125,7 @@ impl FighterStateImpl for HitstunState {
         }
     }
 
-    fn is_visually_grounded<'a>(
+    fn is_visually_grounded<'a>(&'a self) -> bool {
-        &'a self,
-    ) -> bool {
         match self.hitstop_kind {
             HitstopStateKind::Grounded(_) => true,
             HitstopStateKind::Airborne => false,

src/fighter/state/jump.rs

@@ -2,16 +2,10 @@ use bevy::prelude::*;
 
 use crate::{
     fighter::{
-        animation::AnimKind,
+        animation::AnimKind, state::{
-        state::{
+            CollisionContext, EnterContext, FighterState, FighterStateImpl, InterruptContext, UpdateContext, air::{self, AirborneStateCommon}, air_dodge::{self, AirDodgeState}, ground::{self, GroundedStateCommon},
-            CollisionContext, EnterContext, FighterState, FighterStateImpl, InterruptContext,
-            UpdateContext, air,
-            air_dodge::{self, AirDodgeState},
-            ground::{self, GroundedStateCommon},
         },
-    },
+    }, input::FighterCommands, math::{int::FGi32, vec::FGVec2},
-    input::FighterCommands,
-    math::{int::FGi32, vec::FGVec2},
 };
 #[derive(Debug, Hash, Clone, Copy)]
 pub enum JumpType {
@@ -23,6 +17,7 @@ pub enum JumpType {
 #[derive(Debug, Clone, Hash)]
 pub struct JumpState {
     jump_type: JumpType,
+    airborne_state_common: AirborneStateCommon,
 }
 
 #[derive(Debug, Clone, Hash)]
@@ -74,7 +69,7 @@ impl FighterStateImpl for JumpSquatState {
             } else {
                 JumpType::ShortHop
             };
-            Some(FighterState::Jump(JumpState { jump_type }))
+            Some(FighterState::Jump(JumpState { jump_type, airborne_state_common: AirborneStateCommon::default() }))
         } else {
             None
         }
@@ -110,6 +105,7 @@ 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()
             }))
         } else {
             air_dodge::check_input(state_context)
@@ -117,7 +113,7 @@ impl FighterStateImpl for JumpState {
     }
 
     fn update(&mut self, state_context: &mut UpdateContext) {
-        air::update_standard_motion(state_context);
+        air::update_standard_motion(state_context, &mut self.airborne_state_common);
     }
 
     fn on_enter(&mut self, state_context: &mut EnterContext) {
@@ -205,6 +201,7 @@ pub fn check_input_double_jump(state_context: &InterruptContext) -> Option<Fight
         .then(|| {
             FighterState::Jump(JumpState {
                 jump_type: JumpType::DoubleJump,
+                airborne_state_common: AirborneStateCommon::default()
             })
         })
 }

src/fighter/state/mod.rs

@@ -148,7 +148,7 @@ pub struct ExitContext<'a> {
 pub struct UpdateContext<'a> {
     pub translation: &'a mut FighterTranslation,
     pub prev_translation: &'a mut FighterPreviousTranslation,
-    pub input: &'a FighterInput,
+    pub input: &'a mut FighterInput,
     pub hitboxes: &'a mut FighterHitboxes,
     pub velocity: &'a mut FighterVelocity,
     pub knockback_velocity: &'a mut FighterKnockbackVelocity,
@@ -289,7 +289,7 @@ impl<'w, 's> FighterFrameQueryItem<'w, 's> {
         UpdateContext {
             translation: &mut self.translation,
             prev_translation: &mut self.prev_translation,
-            input: &self.input,
+            input: &mut self.input,
             hitboxes: &mut self.hitboxes,
             velocity: &mut self.velocity,
             knockback_velocity: &mut self.knockback_velocity,

src/input/buffer.rs

@@ -20,6 +20,8 @@ pub enum FighterCommands {
     Jump,
     Shield,
     Attack,
+    SmashMoveUp,
+    SmashMoveDown,
     SmashMoveLeft,
     SmashMoveRight,
 }
@@ -60,6 +62,8 @@ impl FighterAttackCommandType {
 pub struct FighterCommandLifetimes {
     smash_move_left: u8,
     smash_move_right: u8,
+    smash_move_down: u8,
+    smash_move_up: u8,
     jump: u8,
     shield: u8,
     attack: u8,
@@ -72,6 +76,8 @@ impl Index<FighterCommands> for FighterCommandLifetimes {
         match command {
             FighterCommands::SmashMoveLeft => &self.smash_move_left,
             FighterCommands::SmashMoveRight => &self.smash_move_right,
+            FighterCommands::SmashMoveDown => &self.smash_move_down,
+            FighterCommands::SmashMoveUp => &self.smash_move_up,
             FighterCommands::Jump => &self.jump,
             FighterCommands::Shield => &self.shield,
             FighterCommands::Attack => &self.attack,
@@ -84,6 +90,8 @@ impl IndexMut<FighterCommands> for FighterCommandLifetimes {
         match command {
             FighterCommands::SmashMoveLeft => &mut self.smash_move_left,
             FighterCommands::SmashMoveRight => &mut self.smash_move_right,
+            FighterCommands::SmashMoveDown => &mut self.smash_move_down,
+            FighterCommands::SmashMoveUp => &mut self.smash_move_up,
             FighterCommands::Jump => &mut self.jump,
             FighterCommands::Shield => &mut self.shield,
             FighterCommands::Attack => &mut self.attack,
@@ -221,6 +229,19 @@ pub fn postprocess_input(
         let mut x_flick_detected =
             x_abs >= axis_threshold && input.frames_in_x_flick_deadzone <= frame_threshold;
 
+        if y_flick_detected {
+            input.clear_command(FighterCommands::SmashMoveUp);
+            input.clear_command(FighterCommands::SmashMoveDown);
+
+            let command_to_set = if input.current_frame.movement.y > 0.0 {
+                FighterCommands::SmashMoveUp
+            } else {
+                FighterCommands::SmashMoveDown
+            };
+
+            input.set_lifetime(command_to_set, game_settings.input_common.input_buffer_size);
+        }
+
         // if both flicks are detected, only one wins
 
         if x_flick_detected && y_flick_detected {