Specify ground to air transitions and thresholds (#41)

Reviewed-on: #41
Co-authored-by: Álex Román Núñez <eirexe@eirteam.moe>

src/fighter/attack/mod.rs

@@ -43,6 +43,7 @@ pub enum HitReactionKind {
 #[derive(Debug, Hash, Clone)]
 pub struct FighterHitReaction {
     pub launch_velocity: FGVec2,
+    pub launch_angle: FGi32,
     pub hitstop_frames: HitStop,
     pub hitstun_frames: u32,
     pub kind: HitReactionKind,
@@ -62,10 +63,13 @@ pub struct FighterLastAttackDebug {
     pub trajectory_points: Vec<Vec3>,
 }
 
-#[derive(Debug, Default, Clone, Deref, DerefMut, Hash)]
+#[derive(Debug, Default, Clone, Deref, DerefMut, Hash, PartialEq, PartialOrd)]
 pub struct HitStop(u32);
 
 impl HitStop {
+    pub fn new(hitstop: u32) -> Self {
+        HitStop(hitstop)
+    }
     pub fn calculate(attack_damage_stalled: FighterDamage, crouch_cancelling: bool) -> Self {
         let a = (attack_damage_stalled.0 / FGi32::lit("3.0") + FGi32::lit("4.0")).round_to_zero();
         let crouch_cancelling_factor = if crouch_cancelling {

src/fighter/attack/reaction.rs

@@ -104,6 +104,7 @@ pub fn resolve_fighter_hits(
                 attacker_slot,
                 FighterHitReaction {
                     launch_velocity: launch_direction * knockback.get_launch_speed(&game_settings),
+                    launch_angle,
                     hitstun_frames: knockback.get_hitstun_frames(&game_settings),
                     hitstop_frames: hitstop,
                     kind: HitReactionKind::Flinch,

src/fighter/state/mod.rs

@@ -7,8 +7,7 @@ use bevy::prelude::*;
 
 use crate::fighter::animation::{AnimKind, FighterAnimationFrame};
 use crate::fighter::attack::{
-    FighterAttackScriptAssets, FighterKnockbackVelocity, FighterPendingHitReaction,
+    FighterAttackScriptAssets, FighterKnockbackVelocity, FighterPendingHitReaction, FighterStaleMoveQueue, HitStop,
-    FighterStaleMoveQueue,
 };
 use crate::fighter::attributes::FighterAttributes;
 use crate::fighter::baked_animation::BakedFighterAnimations;
@@ -22,6 +21,7 @@ use crate::fighter::{
 };
 use crate::game_settings::GameSettings;
 use crate::input::FighterInput;
+use crate::math::int::FGi32;
 use crate::scripting::FighterAttackScript;
 use crate::stage::line::StageCollision;
 
@@ -391,7 +391,7 @@ pub fn state_interrupt_system(
 
         let new_state = if let Some(reaction) = pending_hit_reaction.take() {
             hitstop.remaining_frames = *reaction.hitstop_frames;
-            let hitstop_kind = match &*state {
+            let mut hitstop_kind = match &*state {
                 FighterState::Wait(value) => {
                     hitstun::HitstopStateKind::Grounded(value.grounded_common.clone())
                 }
@@ -412,6 +412,26 @@ pub fn state_interrupt_system(
                 }
                 _ => hitstun::HitstopStateKind::Airborne,
             };
+
+            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) {
+                    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 {
+                        hitstop_kind = hitstun::HitstopStateKind::Airborne;
+                } else {
+                    // straight down is 270
+                    let straight_down_angle = FGi32::lit("270.0");
+                    let meteor_threshold = game_settings.fighter_common.meteor_angle_threshold;
+                    if (reaction.launch_angle - straight_down_angle).abs() <= meteor_threshold {
+                        // TODO: Floor bounce
+                        hitstop_kind = hitstun::HitstopStateKind::Airborne;
+                    }
+                }
+            }
+
+            info!("Entering hitstop kind: {:?}", hitstop_kind);
             Some(FighterState::Hitstun(HitstunState {
                 hit_reaction: reaction,
                 hitstop_kind,

src/game_settings.rs

@@ -9,12 +9,28 @@ use crate::{math::int::FGi32, menus::style::FGUiStyle};
 #[reflect(opaque)]
 pub struct FighterSettingsCommon {
     pub walk_speed_ease: FGi32,
+
+    /// Maximum allowed horizontal velocity
     pub ground_max_horizontal_velocity: FGi32,
+
+    /// Ground friction applied when the fighter is above the walk speed
     pub ground_friction_over_walk_speed_multiplier: FGi32,
     pub knockback_stacking_window: u32,
     pub knockback_decay_per_frame: FGi32,
+
+    /// Multiplier that translates knockback -> game unit velocity
     pub knockback_launch_velocity_multiplier: FGi32,
     pub hitstun_frames_per_unit_knockback: FGi32,
+
+    /// If an attack's hitstop > this value it will cause a grounded fighter to either bounce (if a meteor/spike)
+    /// or to become airborne
+    pub tumble_bounce_hitstop_threshold: u32,
+
+    /// Angle diff from straight down under which the attack will count as a meteor
+    pub meteor_angle_threshold: FGi32,
+
+    /// Angle diff from straight up under which the attack will force an airborne state 
+    pub attack_ground_to_airborne_transition_vertical_angle_threshold: FGi32,
 }
 #[derive(Reflect, Serialize, Deserialize, Clone)]
 #[reflect(opaque)]