Port to fixed point math

Cargo.lock

@@ -3234,6 +3234,7 @@ dependencies = [
  "az",
  "bytemuck",
  "half",
+ "serde",
  "typenum",
 ]
 

Cargo.toml

@@ -29,7 +29,7 @@ serde = "1.0.229"
 bitfields = "3.0.0"
 clap = { version = "4.6.6", features = ["derive"] }
 bevy_wind_waker_shader = { git = "https://github.com/lavaeater/bevy_wind_waker_shader.git" }
-fixed = "1.31.0"
+fixed = { version = "1.31.0", features = ["serde"] }
 
 # Enable a small amount of optimization in the dev profile.
 [profile.dev]

src/fighter/animation.rs

@@ -13,7 +13,7 @@ pub struct FighterAnimationPlayerLink(Entity);
 pub fn apply_fighter_translation_to_visuals(query: Query<(&FighterTranslation, &FighterECB, &mut Transform)>) {
     for (translation, ecb, mut transform) in query {
         let translation = translation.0 + ecb.get_bottom_point();
-        transform.translation = Vec3::new(translation.x, translation.y, 0.0);
+        transform.translation = Vec3::new(translation.x.to_num(), translation.y.to_num(), 0.0);
     }
 }
 

src/fighter/attributes.rs

@@ -1,31 +1,32 @@
 use bevy::prelude::*;
 
-use crate::input::FighterInputFrame;
+use crate::{input::FighterInputFrame, math::int::FGi32};
 
 /// Per-fighter tuning values. These are character data, not global rules —
 /// anything that applies to every fighter belongs in
 /// [`crate::game_settings::FighterSettingsCommon`] instead.
 #[derive(Component, Clone, Copy)]
 pub struct FighterAttributes {
-    pub base_walk_accel: f32,
+    pub base_walk_accel: FGi32,
-    pub stick_walk_accel: f32,
+    pub stick_walk_accel: FGi32,
-    pub max_walk_vel: f32,
+    pub max_walk_vel: FGi32,
 
     pub dash_duration: u32,
-    pub dash_initial_velocity: f32,
+    pub dash_initial_velocity: FGi32,
-    pub base_dash_accel: f32,
+    pub base_dash_accel: FGi32,
-    pub stick_dash_accel: f32,
+    pub stick_dash_accel: FGi32,
-    pub max_dash_vel: f32,
+    pub max_dash_vel: FGi32,
 
-    pub jump_vertical_velocity: f32,
+    pub jumpsquat_duration: u32,
+    pub jump_vertical_velocity: FGi32,
 
-    pub ground_friction: f32,
+    pub ground_friction: FGi32,
-    pub terminal_velocity: f32,
+    pub terminal_velocity: FGi32,
-    pub gravity: f32,
+    pub gravity: FGi32,
 }
 
 impl FighterAttributes {
-    pub fn get_accel_and_target_dashrun(&self, input: &FighterInputFrame) -> (f32, f32) {
+    pub fn get_accel_and_target_dashrun(&self, input: &FighterInputFrame) -> (FGi32, FGi32) {
         let accel = input.movement.x * self.stick_dash_accel;
         let accel = accel + input.movement.x.signum() * self.base_dash_accel;
         let target_vel = input.movement.x * self.max_dash_vel;
@@ -33,7 +34,7 @@ impl FighterAttributes {
         (accel, target_vel)
     }
 
-    pub fn get_accel_and_target_walk(&self, input: &FighterInputFrame) -> (f32, f32) {
+    pub fn get_accel_and_target_walk(&self, input: &FighterInputFrame) -> (FGi32, FGi32) {
         let accel = input.movement.x * self.stick_walk_accel;
         let accel = accel + input.movement.x.signum() * self.base_walk_accel;
         let target_vel = input.movement.x * self.max_walk_vel;

src/fighter/collision.rs

@@ -5,6 +5,8 @@ use bevy::{color::palettes::css::HOT_PINK, prelude::*};
 use crate::fighter::ecb::FighterPreviousECB;
 use crate::fighter::state::FighterStateContext;
 use crate::fighter::{FighterECB, FighterPreviousTranslation, FighterTranslation, FighterVelocity};
+use crate::math::segment::FGSegment2d;
+use crate::math::vec::FGVec2;
 use crate::stage::StagePoly;
 use crate::stage::line::{StageCollision, StageLineID};
 /*
@@ -36,14 +38,14 @@ pub fn collide_fighter_with_scene(
 
 pub struct AirCollisionWithStageResult {
     pub line_id: StageLineID,
-    pub hit_position: Vec2,
+    pub hit_position: FGVec2,
-    pub hit_normal: Vec2,
+    pub hit_normal: FGVec2,
 }
 
 pub fn air_collide_with_stage(
     state_context: &FighterStateContext,
 ) -> Option<AirCollisionWithStageResult> {
-    let ray_segment = Segment2d::new(
+    let ray_segment = FGSegment2d::new(
         state_context.prev_translation.0 + state_context.prev_ecb.get_bottom_point(),
         state_context.translation.0 + state_context.ecb.get_bottom_point(),
     );

src/fighter/debug.rs

@@ -1,16 +1,20 @@
 //! Fighter debug views: gizmos and the egui inspector window.
 
+use bevy::color::palettes::css::ORANGE;
 use bevy::{color::palettes::css::YELLOW, prelude::*};
 use bevy_egui::{EguiContexts, egui};
 
+use crate::fighter::ecb::FighterPreviousECB;
 use crate::fighter::state::StateNameDebug;
-use crate::fighter::{FighterECB, FighterTranslation, FighterVelocity};
+use crate::fighter::{FighterECB, FighterPreviousTranslation, FighterTranslation, FighterVelocity};
 use crate::input::FighterInput;
 
-pub fn debug_draw_ecb(ecbs: Query<(&FighterECB, &FighterTranslation)>, mut gizmos: Gizmos) {
+pub fn debug_draw_ecb(ecbs: Query<(&FighterECB, &FighterTranslation, &FighterPreviousECB, &FighterPreviousTranslation)>, mut gizmos: Gizmos) {
-    for (ecb, trf) in ecbs {
+    for (ecb, trf, ecb_prev, trf_prev) in ecbs {
-        let transformed = ecb.to_3d_lineloop(Transform::from_xyz(trf.x, trf.y, 0.0));
+        let transformed = ecb.to_3d_lineloop(Transform::from_xyz(trf.x.to_num(), trf.y.to_num(), 0.0));
         gizmos.lineloop(transformed, YELLOW);
+        let prev_transformed = ecb_prev.to_3d_lineloop(Transform::from_xyz(trf_prev.x.to_num(), trf_prev.y.to_num(), -0.1));
+        gizmos.lineloop(prev_transformed, ORANGE);
     }
 }
 

src/fighter/ecb.rs

@@ -1,4 +1,7 @@
 use bevy::prelude::*;
+use fixed::traits::Fixed;
+
+use crate::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
@@ -6,40 +9,74 @@ use bevy::prelude::*;
 #[derive(Component, Debug, Clone, Copy)]
 #[require(FighterPreviousECB)]
 pub struct FighterECB {
-    pub vertical_half: f32,
+    pub vertical_half: FGi32,
-    pub horizontal_half: f32,
+    pub horizontal_half: FGi32,
 }
 
 #[derive(Component, Debug, Clone, Copy, Default)]
 pub struct FighterPreviousECB {
-    pub vertical_half: f32,
+    pub vertical_half: FGi32,
-    pub horizontal_half: f32,
+    pub horizontal_half: FGi32,
+}
+
+impl From<FighterECB> for FighterPreviousECB {
+    fn from(ecb: FighterECB) -> Self {
+        Self {
+            vertical_half: ecb.vertical_half,
+            horizontal_half: ecb.horizontal_half,
+        }
+    }
+}
+
+pub fn snapshot_fighter_ecb(
+    fighters: Query<(&FighterECB, &mut FighterPreviousECB)>,
+) {
+    for (ecb, mut previous_ecb) in fighters {
+        *previous_ecb = (*ecb).into();
+    }
 }
 
 impl FighterECB {
     pub fn to_3d_lineloop(&self, trf: Transform) -> [Vec3; 4] {
-        let rel_up = trf.transform_point(Vec3::new(0.0, self.vertical_half, 0.0));
+        let rel_up = trf.transform_point(Vec3::new(0.0, self.vertical_half.to_num(), 0.0));
-        let rel_down = trf.transform_point(Vec3::new(0.0, -self.vertical_half, 0.0));
+        let rel_down = trf.transform_point(Vec3::new(0.0, (-self.vertical_half).to_num(), 0.0));
-        let rel_left = trf.transform_point(Vec3::new(-self.horizontal_half, 0.0, 0.0));
+        let rel_left = trf.transform_point(Vec3::new((-self.horizontal_half).to_num(), 0.0, 0.0));
-        let rel_right = trf.transform_point(Vec3::new(self.horizontal_half, 0.0, 0.0));
+        let rel_right = trf.transform_point(Vec3::new(self.horizontal_half.to_num(), 0.0, 0.0));
         [rel_up, rel_right, rel_down, rel_left]
     }
 
-    pub fn get_bottom_point(&self) -> Vec2 {
+    pub fn get_bottom_point(&self) -> FGVec2 {
-        Vec2::new(0.0, -self.vertical_half)
+        FGVec2::new(FGi32::ZERO, -self.vertical_half)
     }
 }
 
 impl FighterPreviousECB {
     pub fn to_3d_lineloop(&self, trf: Transform) -> [Vec3; 4] {
-        let rel_up = trf.transform_point(Vec3::new(0.0, self.vertical_half, 0.0));
+        let rel_up = trf.transform_point(Vec3::new(0.0, self.vertical_half.to_num(), 0.0));
-        let rel_down = trf.transform_point(Vec3::new(0.0, -self.vertical_half, 0.0));
+        let rel_down = trf.transform_point(Vec3::new(0.0, (-self.vertical_half).to_num(), 0.0));
-        let rel_left = trf.transform_point(Vec3::new(-self.horizontal_half, 0.0, 0.0));
+        let rel_left = trf.transform_point(Vec3::new((-self.horizontal_half).to_num(), 0.0, 0.0));
-        let rel_right = trf.transform_point(Vec3::new(self.horizontal_half, 0.0, 0.0));
+        let rel_right = trf.transform_point(Vec3::new(self.horizontal_half.to_num(), 0.0, 0.0));
         [rel_up, rel_right, rel_down, rel_left]
     }
 
-    pub fn get_bottom_point(&self) -> Vec2 {
+    pub fn get_bottom_point(&self) -> FGVec2 {
-        Vec2::new(0.0, -self.vertical_half)
+        FGVec2::new(FGi32::ZERO, -self.vertical_half)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn previous_ecb_copies_current_dimensions() {
+        let current = FighterECB {
+            vertical_half: FGi32::lit("0.5"),
+            horizontal_half: FGi32::lit("0.25"),
+        };
+        let previous = FighterPreviousECB::from(current);
+
+        assert_eq!(previous.vertical_half, current.vertical_half);
+        assert_eq!(previous.horizontal_half, current.horizontal_half);
     }
 }

src/fighter/mod.rs

@@ -45,7 +45,12 @@ impl Plugin for FighterPlugin {
             // Every state gets a chance to interrupt itself, in priority order.
             .add_systems(
                 GgrsSchedule,
-                (animation::setup_fighter_animation_player, state::state_interrupt_system,).in_set(GameplaySet::Interrupt),
+                (
+                    ecb::snapshot_fighter_ecb.before(state_interrupt_system),
+                    animation::setup_fighter_animation_player,
+                    state::state_interrupt_system,
+                )
+                    .in_set(GameplaySet::Interrupt),
             )
             .add_systems(
                 GgrsSchedule,
@@ -74,6 +79,7 @@ impl Plugin for FighterPlugin {
             // components; a component simulated here but missing from this list
             // is a desync waiting to happen.
             .rollback_component_with_copy::<FighterECB>()
+            .rollback_component_with_copy::<ecb::FighterPreviousECB>()
             .rollback_component_with_copy::<FighterVelocity>()
             .rollback_component_with_copy::<FighterTranslation>()
             .rollback_component_with_copy::<FighterPreviousTranslation>()

src/fighter/motion.rs

@@ -3,20 +3,20 @@
 
 use bevy::prelude::*;
 
-use crate::fighter::FighterAttributes;
+use crate::{fighter::FighterAttributes, math::vec::FGVec2};
 
 #[derive(Component, Clone, Copy)]
 pub struct Grounded;
 
 #[derive(Component, Deref, DerefMut, Default, Debug, Clone, Copy)]
-pub struct FighterVelocity(pub Vec2);
+pub struct FighterVelocity(pub FGVec2);
 
 #[derive(Component, Deref, DerefMut, Default, Clone, Copy)]
-pub struct FighterPreviousTranslation(pub Vec2);
+pub struct FighterPreviousTranslation(pub FGVec2);
 
 #[derive(Component, Deref, DerefMut, Default, Clone, Copy)]
 #[require(FighterPreviousTranslation)]
-pub struct FighterTranslation(pub Vec2);
+pub struct FighterTranslation(pub FGVec2);
 
 pub fn apply_air_motion(
     fighters: Query<(
@@ -37,7 +37,7 @@ pub fn copy_fighter_transform_to_visuals(
     fighters: Query<(&FighterTranslation, &mut Transform)>,
 ) {
     for (translation, mut transform) in fighters {
-        transform.translation = Vec3::new(translation.x, translation.y, 0.0);
+        transform.translation = Vec3::new(translation.x.to_num(), translation.y.to_num(), 0.0);
     }
 }
 

src/fighter/state/dash.rs

@@ -2,7 +2,7 @@ use std::hash::{Hash, Hasher};
 
 use bevy::prelude::*;
 
-use super::{FighterStateImpl, FighterStateContext, FighterStateTransition, ground, run, wait, walk};
+use super::{FighterStateImpl, FighterStateContext, ground, run, wait, walk};
 use crate::fighter::state::ground::GroundedStateCommon;
 use crate::fighter::state::wait::WaitState;
 use crate::fighter::state::{FighterState};
@@ -12,11 +12,12 @@ use crate::input::{
     FighterCommands::{SmashMoveLeft, SmashMoveRight},
     FighterInput,
 };
+use crate::math::int::FGi32;
 
 #[derive(Debug, Clone)]
 pub struct DashState {
     frames_in_dash: u32,
-    direction: f32,
+    direction: FGi32,
     ground_common: GroundedStateCommon
 }
 
@@ -28,7 +29,7 @@ impl std::hash::Hash for DashState {
 }
 
 impl DashState {
-    pub fn new(direction: f32, ground_common: GroundedStateCommon) -> Self {
+    pub fn new(direction: FGi32, ground_common: GroundedStateCommon) -> Self {
         Self {
             frames_in_dash: 0,
             direction,
@@ -98,11 +99,11 @@ impl FighterStateImpl for DashState {
     }
 }
 
-fn check_smash_input_with_dir(state_context: &FighterStateContext) -> Option<f32> {
+fn check_smash_input_with_dir(state_context: &FighterStateContext) -> Option<FGi32> {
     if state_context.input.has_command(SmashMoveLeft) {
-        return Some(-1.0);
+        return Some(FGi32::NEG_ONE);
     } else if state_context.input.has_command(SmashMoveRight) {
-        return Some(1.0);
+        return Some(FGi32::ONE);
     } else {
         None
     }

src/fighter/state/fall.rs

@@ -1,6 +1,6 @@
 use bevy::prelude::*;
 
-use super::{FighterStateImpl, FighterStateContext, FighterStateTransition, ground, walk};
+use super::{FighterStateImpl, FighterStateContext, ground, walk};
 use crate::fighter::state::{FighterState, air};
 use crate::fighter::state::ground::GroundedStateCommon;
 use crate::fighter::state::wait::WaitState;

src/fighter/state/ground.rs

@@ -7,17 +7,20 @@ use crate::fighter::{
     FighterAttributes, FighterECB, FighterPreviousTranslation, FighterTranslation, FighterVelocity,
 };
 use crate::game_settings::GameSettings;
+use crate::math::int::FGi32;
+use crate::math::vec::FGVec2;
 use crate::stage::StagePoly;
 use crate::stage::line::{StageCollision, StageLineID, StagePolyLineSegment, StagePolyLineSegmentType};
 
 use bevy::prelude::*;
+use fixed::traits::Fixed;
 
 #[derive(Reflect, Hash, Clone, Debug)]
 pub struct GroundedStateCommon {
     pub current_line_id: StageLineID,
 }
 
-pub fn apply_grounded_friction(friction: f32, ground_vel: f32) -> f32 {
+pub fn apply_grounded_friction(friction: FGi32, ground_vel: FGi32) -> FGi32 {
     if friction.abs() > ground_vel.abs() {
         -ground_vel
     } else {
@@ -28,21 +31,21 @@ pub fn apply_grounded_friction(friction: f32, ground_vel: f32) -> f32 {
 pub fn move_accelerate() {}
 
 pub fn compute_ground_accel(
-    accel: f32,
+    accel: FGi32,
-    target_vel: f32,
+    target_vel: FGi32,
-    gr_vel: f32,
+    gr_vel: FGi32,
     attribs: &FighterAttributes,
     game_settings: &GameSettings,
-) -> f32 {
+) -> FGi32 {
     if target_vel == 0.0 {
         apply_grounded_friction(attribs.ground_friction, gr_vel)
     } else {
         let mut accel = accel;
         let ground_max_horizontal_velocity =
             game_settings.figher_common.ground_max_horizontal_velocity;
-        if !(gr_vel * accel < 0.0) {
+        if !(gr_vel * accel < FGi32::ZERO) {
             // accelerating, not reversing
-            if accel > 0.0 {
+            if accel > FGi32::ZERO {
                 if gr_vel + accel > target_vel {
                     accel = -attribs.ground_friction;
                     if gr_vel + accel < target_vel {
@@ -78,7 +81,7 @@ pub fn apply_grounded_motion(
 ) {
     // Vertical velocity should be 0 on the ground
     prev_translation.0 = translation.0;
-    translation.0 += Vec2::new(velocity.0.x ,0.0);
+    translation.0 += FGVec2::new(velocity.0.x ,FGi32::ZERO);
 }
 
 pub fn collide_with_stage_grounded(
@@ -96,34 +99,29 @@ pub fn collide_with_stage_grounded(
 
     if let Some(stage_poly) = stage_poly {
         let ecb_bottom_pos = translation.0 + ecb.get_bottom_point();
-        let left_segment_idx = ground_common
+        let current_segment_idx = ground_common.current_line_id.segment;
-            .current_line_id
-            .segment
-            .checked_sub(1)
-            .unwrap_or(0);
-        let right_segment_idx =
-            (ground_common.current_line_id.segment + 1) % stage_poly.segments.len();
 
         // First, we check the current segment, if that fails, we check the surrounding ones
         let grounded_ecb_bottom_pos = [
-            ground_common.current_line_id.segment.clone(),
+            Some(current_segment_idx),
-            left_segment_idx,
+            stage_poly.get_prev_segment_index(current_segment_idx),
-            right_segment_idx,
+            stage_poly.get_next_segment_index(current_segment_idx),
         ]
-        .iter()
+        .into_iter()
+        .flatten()
         .find_map(|segment_idx| {
-            let segment = stage_poly.get_segment(*segment_idx)?;
+            let segment = stage_poly.get_segment(segment_idx)?;
             if segment.segment_type != StagePolyLineSegmentType::Floor {
                 return None;
             }
 
             let line_dir = segment.segment.direction();
-            let projected_point = segment.segment.point1() + (ecb_bottom_pos - segment.segment.point1()).project_onto(line_dir.as_vec2());
+            let projected_point = segment.segment.point1() + (ecb_bottom_pos - segment.segment.point1()).project_onto(line_dir);
             let closest_point = segment.segment.closest_point(ecb_bottom_pos);
             let distance = closest_point.distance(projected_point);
-            
+
             if distance < 0.01 {
-                return Some((projected_point, *segment_idx, segment.normal));
+                return Some((projected_point, segment_idx, segment.normal));
             }
 
             None

src/fighter/state/jump.rs

@@ -1,41 +1,106 @@
 use bevy::prelude::*;
 
-use crate::fighter::state::{FighterState, FighterStateImpl};
+use crate::{
+    fighter::state::{
+        FighterState, FighterStateContext, FighterStateImpl,
+        fall::FallState,
+        ground::{self, GroundedMotionResult, GroundedStateCommon},
+    },
+    input::FighterCommands,
+};
 
-pub struct JumpState {
+pub enum JumpType {
-    pub counter: u32
+    ShortHop,
+    LongJump,
+    DoubleJump,
 }
 
+#[derive(Debug, Clone, Hash)]
+pub struct JumpState {}
+
+#[derive(Debug, Clone, Hash)]
 pub struct JumpSquatState {
-    pub counter: u32
+    pub grounded_common: GroundedStateCommon,
+    pub duration_counter: u32,
 }
 
+impl JumpSquatState {
+    pub fn create(grounded_common: GroundedStateCommon) -> Self {
+        Self {
+            grounded_common,
+            duration_counter: 0,
+        }
+    }
+}
 
 impl FighterStateImpl for JumpSquatState {
     const NAME: &'static str = "JumpSquat";
-    fn check_interrupt(
+
-        &self,
+    fn check_interrupt(&self, state_context: &FighterStateContext) -> Option<FighterState> {
-        state_context: &super::FighterStateContext,
+        if self.duration_counter >= state_context.fighter_attribs.jumpsquat_duration {
-    ) -> Option<FighterState> {
+            Some(FighterState::Jump(JumpState {}))
-        None
+        } else {
+            None
+        }
     }
 
-    fn update(&mut self, _state_context: &mut super::FighterStateContext) {
+    fn update(&mut self, state_context: &mut FighterStateContext) {
-        todo!()
+        self.duration_counter += 1;
+
+        let friction =
+            if state_context.velocity.x.abs() > state_context.fighter_attribs.max_walk_vel {
+                state_context.fighter_attribs.ground_friction
+                    * state_context
+                        .game_settings
+                        .figher_common
+                        .ground_friction_over_walk_speed_multiplier
+            } else {
+                state_context.fighter_attribs.ground_friction
+            };
+
+        let ground_velocity = state_context.velocity.x;
+
+        state_context.velocity.x += ground::apply_grounded_friction(friction, ground_velocity);
+
+        ground::apply_grounded_motion(
+            state_context.velocity,
+            state_context.translation,
+            state_context.prev_translation,
+        );
+    }
+
+    fn check_collision_interrupt(
+        &mut self,
+        state_context: &mut FighterStateContext,
+    ) -> Option<FighterState> {
+        if let GroundedMotionResult::InAir =
+            ground::collide_with_stage_grounded(state_context, &mut self.grounded_common, false)
+        {
+            Some(FighterState::Fall(FallState))
+        } else {
+            None
+        }
     }
-    
 }
 
 impl FighterStateImpl for JumpState {
     const NAME: &'static str = "Jump";
-    fn check_interrupt(
+    fn check_interrupt(&self, state_context: &FighterStateContext) -> Option<FighterState> {
-        &self,
-        state_context: &super::FighterStateContext,
-    ) -> Option<FighterState> {
         None
     }
 
-    fn update(&mut self, _state_context: &mut super::FighterStateContext) {
+    fn update(&mut self, _state_context: &mut FighterStateContext) {}
-        todo!()
+}
-    }
+
-}
+pub fn check_input(
+    state_context: &FighterStateContext,
+    ground_common: &GroundedStateCommon,
+) -> Option<FighterState> {
+    state_context
+        .input
+        .has_command(FighterCommands::Jump)
+        .then_some(FighterState::JumpSquat(JumpSquatState::create(
+            ground_common.clone(),
+        )));
+    None
+}

src/fighter/state/mod.rs

@@ -11,6 +11,7 @@ use crate::fighter::ecb::FighterPreviousECB;
 use crate::fighter::{FighterAttributes, FighterECB, FighterPreviousTranslation, FighterTranslation, FighterVelocity};
 use crate::game_settings::GameSettings;
 use crate::input::FighterInput;
+use crate::math::int::FGi32;
 use crate::schedule::GameplaySet;
 use crate::stage::StagePoly;
 use crate::stage::line::StageCollision;
@@ -24,14 +25,6 @@ pub mod fall;
 pub mod air;
 pub mod jump;
 
-pub enum FighterStateTransition {
-    Wait,
-    Walk,
-    Dash(f32),
-    Run,
-    Fall,
-}
-
 macro_rules! fighter_states {
     ($($variant:ident => $ty:ty),* $(,)?) => {
         #[derive(Component, Clone, Debug, Hash)]
@@ -80,7 +73,7 @@ pub trait FighterStateImpl: Sized {
     }
 }
 
-pub struct FighterStateContext<'a> {
+pub struct FighterStateContext<'a, 'w, 's> {
     pub translation: &'a mut FighterTranslation,
     pub prev_translation: &'a mut FighterPreviousTranslation,
     pub input: &'a mut FighterInput,
@@ -91,6 +84,7 @@ pub struct FighterStateContext<'a> {
     pub game_settings: &'a GameSettings,
     pub entity: Entity,
     pub stage_collision: &'a StageCollision,
+    pub gizmos: Option<&'a mut Gizmos<'w, 's>>,
 }
 
 fighter_states! {
@@ -98,7 +92,9 @@ fighter_states! {
     Walk => walk::WalkState,
     Dash => dash::DashState,
     Run => run::RunState,
-    Fall => fall::FallState
+    Fall => fall::FallState,
+    JumpSquat => jump::JumpSquatState,
+    Jump => jump::JumpState
 }
 
 #[derive(Component)]
@@ -128,6 +124,7 @@ pub fn state_update_system(
             game_settings: &game_settings,
             entity: ent,
             stage_collision: &stage_collision,
+            gizmos: Some(&mut gizmos),
         };
         state.update(&mut update_ctx);
     }
@@ -150,7 +147,8 @@ pub fn state_interrupt_system (
             fighter_attribs: &attribs,
             game_settings: &game_settings,
             entity: ent,
-            stage_collision: &stage_collision
+            stage_collision: &stage_collision,
+            gizmos: None,
         };
         if let Some(new_state) = state.check_interrupt(&state_context) {
             let mut new_state = new_state;
@@ -171,6 +169,7 @@ pub fn state_collision_interrupt_system(
     stage_collision: Res<StageCollision>,
     game_settings: Res<GameSettings>,
     mut commands: Commands,
+    mut gizmos: Gizmos,
 ) {
     for (ent, mut state, mut translation, mut prev_translation, mut input, mut velocity, mut ecb, mut prev_ecb, attribs) in query {
         let mut state_context = FighterStateContext {
@@ -183,7 +182,8 @@ pub fn state_collision_interrupt_system(
             fighter_attribs: &attribs,
             game_settings: &game_settings,
             entity: ent,
-            stage_collision: &stage_collision
+            stage_collision: &stage_collision,
+            gizmos: Some(&mut gizmos),
         };
         if let Some(new_state) = state.check_collision_interrupt(&mut state_context) {
             let mut new_state = new_state;
@@ -197,4 +197,4 @@ pub fn state_collision_interrupt_system(
             info!("State {} -> {}", old_state_name, new_state_name);
         }
     }
-}
+}

src/fighter/state/run.rs

@@ -1,6 +1,6 @@
 use bevy::prelude::*;
 
-use super::{FighterStateImpl, FighterStateContext, FighterStateTransition, ground, wait, walk};
+use super::{FighterStateImpl, FighterStateContext, ground, wait, walk};
 use crate::fighter::state::FighterState;
 use crate::fighter::state::fall::FallState;
 use crate::fighter::state::ground::{GroundedMotionResult, GroundedStateCommon};

src/fighter/state/wait.rs

@@ -1,6 +1,6 @@
 use bevy::prelude::*;
 
-use super::{FighterStateImpl, FighterStateContext, FighterStateTransition, ground, walk};
+use super::{FighterStateImpl, FighterStateContext, ground, walk};
 use crate::fighter::state::FighterState;
 use crate::fighter::state::fall::FallState;
 use crate::fighter::state::ground::{GroundedMotionResult, GroundedStateCommon};
@@ -33,7 +33,10 @@ impl FighterStateImpl for WaitState {
         } else {
             state_context.fighter_attribs.ground_friction
         };
-        state_context.velocity.x += ground::apply_grounded_friction(friction, state_context.velocity.x);
+
+        let ground_velocity = state_context.velocity.x;
+
+        state_context.velocity.x += ground::apply_grounded_friction(friction, ground_velocity);
 
         ground::apply_grounded_motion(
             state_context.velocity,

src/fighter/state/walk.rs

@@ -1,6 +1,6 @@
 use bevy::prelude::*;
 
-use super::{FighterStateImpl, FighterStateContext, FighterStateTransition, dash, ground, wait};
+use super::{FighterStateImpl, FighterStateContext, dash, ground, wait};
 use crate::fighter::state::fall::FallState;
 use crate::fighter::state::ground::{GroundedMotionResult, GroundedStateCommon};
 use crate::fighter::state::{self, FighterState};

src/game_settings.rs

@@ -1,9 +1,11 @@
 use bevy::prelude::*;
 
+use crate::math::int::FGi32;
+
 pub struct FighterSettingsCommon {
-    pub walk_speed_ease: f32,
+    pub walk_speed_ease: FGi32,
-    pub ground_max_horizontal_velocity: f32,
+    pub ground_max_horizontal_velocity: FGi32,
-    pub ground_friction_over_walk_speed_multiplier: f32
+    pub ground_friction_over_walk_speed_multiplier: FGi32
 }
 pub struct InputSettingsCommon {
     pub stick_deadzone: f32,

src/input/buffer.rs

@@ -17,6 +17,7 @@ struct FighterInputBufferedActions {}
 pub enum FighterCommands {
     SmashMoveLeft,
     SmashMoveRight,
+    Jump,
 }
 
 /// Frames of life remaining for each buffered command. Indexed by
@@ -25,6 +26,7 @@ pub enum FighterCommands {
 pub struct FighterCommandLifetimes {
     smash_move_left: u8,
     smash_move_right: u8,
+    jump: u8,
 }
 
 impl Index<FighterCommands> for FighterCommandLifetimes {
@@ -34,6 +36,7 @@ impl Index<FighterCommands> for FighterCommandLifetimes {
         match command {
             FighterCommands::SmashMoveLeft => &self.smash_move_left,
             FighterCommands::SmashMoveRight => &self.smash_move_right,
+            FighterCommands::Jump => &self.jump,
         }
     }
 }
@@ -43,6 +46,7 @@ impl IndexMut<FighterCommands> for FighterCommandLifetimes {
         match command {
             FighterCommands::SmashMoveLeft => &mut self.smash_move_left,
             FighterCommands::SmashMoveRight => &mut self.smash_move_right,
+            FighterCommands::Jump => &mut self.jump,
         }
     }
 }

src/input/frame.rs

@@ -1,10 +1,12 @@
 use bevy::prelude::*;
 use serde::{Deserialize, Serialize};
 
+use crate::math::vec::FGVec2;
+
 /// One frame of a player's raw input. This is the type GGRS serializes and
 /// sends over the wire, so keep it small and keep it `PartialEq`.
 #[derive(Copy, Clone, Debug, PartialEq, Default, Serialize, Deserialize)]
 pub struct FighterInputFrame {
-    pub movement: Vec2,
+    pub movement: FGVec2,
-    pub directional_attack: Vec2,
+    pub directional_attack: FGVec2,
 }

src/input/keyboard.rs

@@ -6,6 +6,7 @@ use bevy::prelude::*;
 use bevy_ggrs::{LocalInputs, LocalPlayers};
 
 use crate::input::{BaseInputMap, FighterInputFrame, InputActionState, InputMapAction};
+use crate::math::int::FGi32;
 use crate::netcode::GGRSCfg;
 
 pub fn preprocess_keyboard_input(
@@ -32,16 +33,16 @@ pub fn preprocess_keyboard_input(
             };
 
             let action_strength = match action_state {
-                InputActionState::JustPressed | InputActionState::Pressed => 1.0f32,
+                InputActionState::JustPressed | InputActionState::Pressed => FGi32::ONE,
-                InputActionState::JustReleased | InputActionState::Released => 0.0f32,
+                InputActionState::JustReleased | InputActionState::Released => FGi32::ZERO,
             };
 
             match keyboard_elment.action {
                 InputMapAction::MovementXDir(sign) => {
-                    input_frame.movement.x += (sign as f32) * action_strength
+                    input_frame.movement.x += (sign) * action_strength
                 }
                 InputMapAction::MovementYDir(sign) => {
-                    input_frame.movement.y += (sign as f32) * action_strength
+                    input_frame.movement.y += (sign) * action_strength
                 }
                 InputMapAction::Jump => todo!(),
             }

src/lib.rs

@@ -29,7 +29,7 @@ use jackdaw_runtime::prelude::*;
 use crate::{
     fighter::{
         FighterAttributes, FighterECB, FighterTranslation, FighterVelocity, FighterVisual, animation::FighterAnimations, state::{FighterState, fall::FallState, wait::WaitState},
-    }, game_settings::{FighterSettingsCommon, GameSettings, InputSettingsCommon}, input::FighterInput, player::Player, schedule::GameplaySchedulePlugin,
+    }, game_settings::{FighterSettingsCommon, GameSettings, InputSettingsCommon}, input::FighterInput, math::{int::FGi32, vec::FGVec2}, player::Player, schedule::GameplaySchedulePlugin,
 };
 
 mod args;
@@ -62,24 +62,24 @@ pub fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
                 Name("Fighter".into()),
                 Player { handle: 0 },
                 FighterECB {
-                    vertical_half: 0.5,
+                    vertical_half: FGi32::lit("0.5"),
-                    horizontal_half: 0.25,
+                    horizontal_half: FGi32::lit("0.25"),
                 },
                 FighterVelocity::default(),
-                FighterTranslation(Vec2::new(0.5, 1.25)),
+                FighterTranslation(FGVec2::lit("0.5", "1.25")),
                 FighterAttributes {
-                    base_walk_accel: 0.01,
+                    base_walk_accel: FGi32::lit("0.01"),
-                    stick_walk_accel: 0.02,
+                    stick_walk_accel: FGi32::lit("0.02"),
-                    max_walk_vel: 0.16,
+                    max_walk_vel: FGi32::lit("0.16"),
-                    ground_friction: 0.008,
+                    ground_friction: FGi32::lit("0.008"),
                     dash_duration: 15,
-                    base_dash_accel: 0.002,
+                    base_dash_accel: FGi32::lit("0.002"),
-                    stick_dash_accel: 0.01,
+                    stick_dash_accel: FGi32::lit("0.01"),
-                    max_dash_vel: 0.22,
+                    max_dash_vel: FGi32::lit("0.22"),
-                    jump_vertical_velocity: 0.25,
+                    jump_vertical_velocity: FGi32::lit("0.25"),
-                    dash_initial_velocity: 0.19,
+                    dash_initial_velocity: FGi32::lit("0.19"),
-                    terminal_velocity: 0.28,
+                    terminal_velocity: FGi32::lit("0.28"),
-                    gravity: 0.023,
+                    gravity: FGi32::lit("0.023"),
                 },
                 FighterState::Fall(FallState),
                 FighterInput::default(),
@@ -115,9 +115,9 @@ impl Plugin for GamePlugin {
         .insert_resource(args::Args::parse())
         .insert_resource(GameSettings {
             figher_common: FighterSettingsCommon {
-                walk_speed_ease: 0.5,
+                walk_speed_ease: FGi32::lit("0.5"),
-                ground_max_horizontal_velocity: 0.3,
+                ground_max_horizontal_velocity: FGi32::lit("0.3"),
-                ground_friction_over_walk_speed_multiplier: 2.0,
+                ground_friction_over_walk_speed_multiplier: FGi32::lit("2.0"),
             },
             input_common: InputSettingsCommon::default(),
         });

src/math/segment.rs

@@ -1,12 +1,13 @@
 use bevy::math::{Vec2, primitives::Segment2d};
 
+use bevy::prelude::*;
 use fixed::prelude::*;
 
 use crate::math::vec::FGVec2;
 
 type FGi32 = fixed::FixedI32<fixed::types::extra::U16>;
 
-#[derive(Clone, Copy, PartialEq)]
+#[derive(Clone, Copy, PartialEq, Reflect)]
 pub struct FGSegment2d {
     point1: FGVec2,
     point2: FGVec2
@@ -29,14 +30,72 @@ impl FGSegment2d {
     pub fn point2(&self) -> FGVec2 {
         self.point2
     }
-}
 
-pub trait SegmentIntersection {
+    /// Compute the normalized direction pointing from the first endpoint to the second endpoint.
-    fn segment_intersection(&self, rhs: &Segment2d) -> Option<FGVec2>;
+    ///
-}
+    /// For the non-panicking version, see [`FGVec2::try_direction`].
+    ///
+    /// # Panics
+    ///
+    /// Panics if a valid direction could not be computed, for example when the endpoints are coincident, NaN, or infinite.
+    #[inline]
+    pub fn direction(&self) -> FGVec2 {
+        self.try_direction().expect("Failed to compute the direction of a line segment")
+    }
 
-impl SegmentIntersection for Segment2d {
+    /// Try to compute the normalized direction pointing from the first endpoint to the second endpoint.
-    fn segment_intersection(&self, rhs: &Segment2d) -> Option<Vec2> {
+    ///
+    /// Returns [`Err(InvalidDirectionError)`](InvalidDirectionError) if a valid direction could not be computed,
+    /// for example when the endpoints are coincident, NaN, or infinite.
+    #[inline]
+    pub fn try_direction(&self) -> Option<FGVec2> {
+        self.point1.direction_to(self.point2)
+    }
+
+    /// Returns the point on the [`Segment2d`] that is closest to the specified `point`.
+    #[inline]
+    pub fn closest_point(&self, point: FGVec2) -> FGVec2 {
+        //       `point`
+        //           x
+        //          ^|
+        //         / |
+        //`offset`/  |
+        //       /   |  `segment_vector`
+        //      x----.-------------->x
+        //      0    t               1
+        let segment_vector = self.point2 - self.point1;
+        let offset = point - self.point1;
+        // The signed projection of `offset` onto `segment_vector`, scaled by the length of the segment.
+        let projection_scaled = segment_vector.dot(offset);
+
+        // `point` is too far "left" in the picture
+        if projection_scaled <= 0.0 {
+            return self.point1;
+        }
+
+        let length_squared = segment_vector.length_squared();
+        // `point` is too far "right" in the picture
+        if projection_scaled >= length_squared {
+            return self.point2;
+        }
+
+        // Point lies somewhere in the middle, we compute the closest point by finding the parameter along the line.
+        let t = projection_scaled / length_squared;
+        self.point1 + segment_vector * t
+    }
+
+    /// Compute the normalized counterclockwise normal on the left-hand side of the line segment.
+    ///
+    /// For the non-panicking version, see [`Segment2d::try_left_normal`].
+    ///
+    /// # Panics
+    ///
+    /// Panics if a valid normal could not be computed, for example when the endpoints are coincident
+    pub fn left_normal(&self) -> FGVec2 {
+        self.point1.direction_to(self.point2).map(|o| { FGVec2::new(-o.y, o.x)}).expect("a valid normal could not be computed")
+    }
+
+    pub fn segment_intersection(&self, rhs: &FGSegment2d) -> Option<FGVec2> {
         let p0 = self.point1();
         let p1 = self.point2();
         let p2 = rhs.point1();
@@ -48,45 +107,31 @@ impl SegmentIntersection for Segment2d {
         let s2_y = p3.y - p2.y;
 
         let denom = -s2_x * s1_y + s1_x * s2_y;
-        if denom.abs() < f32::EPSILON {
+        if denom == FGi32::ZERO {
             return None; // Parallel or collinear
         }
 
         let s = (-s1_y * (p0.x - p2.x) + s1_x * (p0.y - p2.y)) / denom;
         let t = ( s2_x * (p0.y - p2.y) - s2_y * (p0.x - p2.x)) / denom;
 
-        if s >= 0.0 && s <= 1.0 && t >= 0.0 && t <= 1.0 {
+        if s >= FGi32::ZERO && s <= FGi32::ONE && t >= FGi32::ZERO && t <= FGi32::ONE {
-            Some(Vec2::new(p0.x + (t * s1_x), p0.y + (t * s1_y)))
+            Some(FGVec2::new(p0.x + (t * s1_x), p0.y + (t * s1_y)))
         } else {
             None
         }
     }
 }
 
-impl SegmentIntersection for Segment2d {
+#[cfg(test)]
-    fn segment_intersection(&self, rhs: &Segment2d) -> Option<Vec2> {
+mod tests {
-        let p0 = self.point1();
+    use super::*;
-        let p1 = self.point2();
-        let p2 = rhs.point1();
-        let p3 = rhs.point2();
-        
-        let s1_x = p1.x - p0.x;
-        let s1_y = p1.y - p0.y;
-        let s2_x = p3.x - p2.x;
-        let s2_y = p3.y - p2.y;
 
-        let denom = -s2_x * s1_y + s1_x * s2_y;
+    #[test]
-        if denom.abs() < f32::EPSILON {
+    fn closest_point_projects_and_clamps_to_segment() {
-            return None; // Parallel or collinear
+        let segment = FGSegment2d::new(FGVec2::lit("-4", "0"), FGVec2::lit("4", "0"));
-        }
 
-        let s = (-s1_y * (p0.x - p2.x) + s1_x * (p0.y - p2.y)) / denom;
+        assert_eq!(segment.closest_point(FGVec2::lit("2", "1")), FGVec2::lit("2", "0"));
-        let t = ( s2_x * (p0.y - p2.y) - s2_y * (p0.x - p2.x)) / denom;
+        assert_eq!(segment.closest_point(FGVec2::lit("-6", "1")), segment.point1());
-
+        assert_eq!(segment.closest_point(FGVec2::lit("6", "1")), segment.point2());
-        if s >= 0.0 && s <= 1.0 && t >= 0.0 && t <= 1.0 {
-            Some(Vec2::new(p0.x + (t * s1_x), p0.y + (t * s1_y)))
-        } else {
-            None
-        }
     }
-}
+}

src/math/vec.rs

@@ -1,14 +1,24 @@
 use bevy::math::Vec2;
-use std::ops::{Add, Div, Mul, Sub};
+use bevy::prelude::*;
+use fixed::types::I32F32;
+use serde::{Deserialize, Serialize};
+use std::ops::{AddAssign, Add, Div, Mul, Sub};
 
 use super::int::FGi32;
 
-#[derive(Clone, Copy, PartialEq)]
+#[derive(Clone, Copy, PartialEq, Default, Debug, Reflect, Serialize, Deserialize)]
+#[reflect(opaque)]
 pub struct FGVec2 {
     pub x: FGi32,
     pub y: FGi32,
 }
 
+impl std::fmt::Display for FGVec2 {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "[{}, {}]", self.x, self.y)
+    }
+}
+
 impl FGVec2 {
     pub const ZERO: Self = Self::new(FGi32::ZERO, FGi32::ZERO);
 
@@ -17,6 +27,11 @@ impl FGVec2 {
         Self { x, y }
     }
 
+    #[inline(always)]
+    pub const fn lit(x: &str, y: &str) -> Self {
+        Self { x: FGi32::lit(x), y: FGi32::lit(y) }
+    }
+
     #[inline(always)]
     pub fn from_i32(x: i32, y: i32) -> Self {
         Self {
@@ -31,17 +46,78 @@ impl FGVec2 {
     }
 
     #[inline]
-    pub fn length(&self) -> FGi32 {
+    pub fn length(self) -> FGi32 {
         (self.x * self.x + self.y * self.y).sqrt()
     }
 
+    /// Returns the vector projection of `self` onto `rhs`.
+    ///
+    /// `rhs` must be normalized.
+    ///
+    /// # Panics
+    ///
+    /// Will panic if `rhs` is not normalized when `glam_assert` is enabled.
     #[inline]
-    pub fn normalized_or_zero(&self) -> Self {
+    #[must_use]
-        let len = self.length();
+    pub fn project_onto_normalized(self, rhs: Self) -> Self {
-        if len.is_zero() {
+        assert!(rhs.is_normalized());
-            Self::ZERO
+
+        rhs * self.dot(rhs)
+    }
+
+    const EPS: FGi32 = FGi32::from_bits(6);
+
+    #[inline]
+    #[must_use]
+    pub fn is_normalized(self) -> bool {
+        let diff = self.length() - FGi32::ONE;
+        diff.abs() <= Self::EPS
+    }
+
+    #[inline]
+    #[must_use]
+    pub fn dot(self, rhs: Self) -> FGi32 {
+        (self.x * rhs.x) + (self.y * rhs.y)
+    }
+
+    #[inline]
+    #[must_use]
+    pub fn project_onto(self, rhs: Self) -> Self {
+        let other_len_sq = rhs.dot(rhs);
+        assert!(other_len_sq != FGi32::ZERO);
+        rhs * (self.dot(rhs) / other_len_sq)
+    }
+
+    #[inline]
+    pub fn normalize_or_zero(&self) -> Self {
+        self.normalize().unwrap_or(FGVec2::ZERO)
+    }
+
+    #[inline]
+    pub fn direction_to(self, to: Self) -> Option<Self> {
+        (to - self).normalize()
+    }
+
+    #[inline]
+    #[must_use]
+    pub fn distance(self, to: Self) -> FGi32 {
+        (to - self).length()
+    }
+
+    #[inline]
+    pub fn normalize(&self) -> Option<Self> {
+        let x = I32F32::from_num(self.x);
+        let y = I32F32::from_num(self.y);
+        let length_squared = x * x + y * y;
+
+        if length_squared.is_zero() {
+            None
         } else {
-            self / len
+            let length = length_squared.sqrt();
+            Some(Self::new(
+                FGi32::from_num(x / length),
+                FGi32::from_num(y / length),
+            ))
         }
     }
 
@@ -78,6 +154,14 @@ impl Sub for FGVec2 {
     }
 }
 
+impl Sub<&FGVec2> for &FGVec2 {
+    type Output = FGVec2;
+    #[inline]
+    fn sub(self, rhs: &FGVec2) -> FGVec2 {
+        (*self).sub(*rhs)
+    }
+}
+
 impl Div for FGVec2 {
     type Output = Self;
 
@@ -113,3 +197,117 @@ impl Div<FGi32> for &FGVec2 {
         (*self).div(rhs)
     }
 }
+
+impl AddAssign for FGVec2 {
+    fn add_assign(&mut self, rhs: Self) {
+        *self = Self {
+            x: self.x + rhs.x,
+            y: self.y + rhs.y 
+        }
+    }
+}
+
+#[cfg(test)]
+mod is_normalized_tests {
+    use super::*;
+    use fixed::types::I16F16 as FGi32;
+
+    // Normalization is computed in Q32.32, so the Q16.16 error comes from the
+    // two final component conversions and length_squared()'s multiplications.
+    const EPS_FIXED_BITS: i32 = 4;
+
+    #[test]
+    fn normalizes_small_axis_vector_without_losing_squared_precision() {
+        let normalized = FGVec2::lit("0.01", "0").normalize().unwrap();
+
+        assert_eq!(normalized, FGVec2::lit("1", "0"));
+        assert!(normalized.is_normalized());
+    }
+
+    #[test]
+    fn measure_normalize_error_bound() {
+        let mut max_abs_diff_bits: i32 = 0;
+        let mut worst_case: Option<(f64, f64, i32)> = None;
+
+        let angle_steps = 3600; // 0.1 degree resolution
+        let magnitudes: &[f64] = &[
+            0.001, 0.01, 0.1, 0.5, 1.0, 2.0, 10.0, 100.0, 1000.0, 30000.0,
+        ];
+
+        for &mag in magnitudes {
+            for i in 0..angle_steps {
+                let theta = (i as f64) * std::f64::consts::TAU / (angle_steps as f64);
+                let x = mag * theta.cos();
+                let y = mag * theta.sin();
+
+                let Some(fx) = FGi32::checked_from_num(x) else { continue };
+                let Some(fy) = FGi32::checked_from_num(y) else { continue };
+
+                let v = FGVec2 { x: fx, y: fy };
+
+                if let Some(normalized) = v.normalize() {
+                    let ls = normalized.length_squared();
+                    let diff_bits = ls.to_bits() - FGi32::ONE.to_bits();
+                    let abs_diff_bits = diff_bits.abs();
+
+                    if abs_diff_bits > max_abs_diff_bits {
+                        max_abs_diff_bits = abs_diff_bits;
+                        worst_case = Some((x, y, abs_diff_bits));
+                    }
+                }
+            }
+        }
+
+        let ulp_value = FGi32::DELTA.to_num::<f64>();
+        println!(
+            "Max |length_squared - 1.0| = {} raw bits ({:e} real), worst case: {:?}",
+            max_abs_diff_bits,
+            max_abs_diff_bits as f64 * ulp_value,
+            worst_case
+        );
+
+        assert!(
+            max_abs_diff_bits <= EPS_FIXED_BITS,
+            "measured error ({} bits) exceeds analytical bound ({} bits) — \
+             revisit the epsilon derivation",
+            max_abs_diff_bits,
+            EPS_FIXED_BITS
+        );
+
+        println!(
+            "Bound: {} bits, measured: {} bits (headroom: {} bits)",
+            EPS_FIXED_BITS,
+            max_abs_diff_bits,
+            EPS_FIXED_BITS - max_abs_diff_bits
+        );
+    }
+
+    #[test]
+    fn is_normalized_behaves_correctly() {
+        let angle_steps = 360;
+        for i in 0..angle_steps {
+            let theta = (i as f64) * std::f64::consts::TAU / (angle_steps as f64);
+            for &mag in &[0.01, 1.0, 100.0, 10000.0] {
+                let x = mag * theta.cos();
+                let y = mag * theta.sin();
+                let Some(fx) = FGi32::checked_from_num(x) else { continue };
+                let Some(fy) = FGi32::checked_from_num(y) else { continue };
+                let v = FGVec2 { x: fx, y: fy };
+
+                if let Some(normalized) = v.normalize() {
+                    assert!(
+                        normalized.is_normalized(),
+                        "normalized({}, {}) failed is_normalized(): length_squared = {:?}",
+                        x, y, normalized.length_squared()
+                    );
+                }
+            }
+        }
+
+        let non_unit = FGVec2 { x: FGi32::from_num(2.0), y: FGi32::from_num(0.0) };
+        assert!(!non_unit.is_normalized());
+
+        let non_unit_small = FGVec2 { x: FGi32::from_num(0.5), y: FGi32::from_num(0.0) };
+        assert!(!non_unit_small.is_normalized());
+    }
+}

src/stage/debug.rs

@@ -5,11 +5,11 @@ use crate::stage::{StagePoly, line::StageCollision};
 pub fn debug_draw_scene(mut gizmos: Gizmos, stage_collision: Res<StageCollision>) {
     for poly in stage_collision.stage_polys.iter() {
         for segment in poly.segments.iter() {
-            let from = segment.segment.point1();
+            let from = segment.segment.point1().to_vec2();
-            let to = segment.segment.point2();
+            let to = segment.segment.point2().to_vec2();
             let from_3d = Vec3::new(from.x, from.y, 0.0);
             let end_3d = Vec3::new(to.x, to.y, 0.0);
-            let normal_3d = Vec3::new(segment.normal.x, segment.normal.y, 0.0);
+            let normal_3d = Vec3::new(segment.normal.x.to_num(), segment.normal.y.to_num(), 0.0);
             gizmos.line(from_3d, end_3d, RED);
             let midpoint = (from_3d + end_3d) * 0.5;
             gizmos.arrow(midpoint, midpoint + normal_3d, RED);

src/stage/line.rs

@@ -4,7 +4,7 @@ use std::default;
 
 use bevy::{math::InvalidDirectionError, prelude::*};
 
-use crate::math::segment::SegmentIntersection;
+use crate::math::{segment::{FGSegment2d}, vec::FGVec2};
 
 #[derive(Reflect, Clone, Copy, PartialEq)]
 pub enum StagePolyLineSegmentType {
@@ -14,8 +14,8 @@ pub enum StagePolyLineSegmentType {
 
 #[derive(Reflect, Clone)]
 pub struct StagePolyLineSegment {
-    pub segment: Segment2d,
+    pub segment: FGSegment2d,
-    pub normal: Vec2,
+    pub normal: FGVec2,
     pub segment_type: StagePolyLineSegmentType
 }
 
@@ -40,9 +40,9 @@ pub struct StagePoly {
 }
 
 pub struct StagePlaneIntersectResult {
-    pub position: Vec2,
+    pub position: FGVec2,
     pub segment_idx: usize,
-    pub normal: Vec2
+    pub normal: FGVec2
 }
 
 #[derive(Resource, Reflect, Clone, Default)]
@@ -52,18 +52,30 @@ pub struct StageCollision {
 }
 
 impl StagePoly {
-    pub fn intersect_ray(&self, ray_segment: Segment2d) -> Option<StagePlaneIntersectResult> {
+    pub fn intersect_ray(&self, ray_segment: FGSegment2d) -> Option<StagePlaneIntersectResult> {
-        for (i, segment) in self.segments.iter().enumerate() {
+        let ray_start = ray_segment.point1();
-            if let Some(intersection) = segment.segment.segment_intersection(&ray_segment) {
+        let (segment_idx, segment, position) = self
-                println!("DIST3 {} {}", intersection, segment.segment.closest_point(intersection));
+            .segments
-                return Some(StagePlaneIntersectResult {
+            .iter()
-                    position: intersection,
+            .enumerate()
-                    segment_idx: i,
+            .filter_map(|(segment_idx, segment)| {
-                    normal: segment.normal
+                segment
-                });
+                    .segment
-            }
+                    .segment_intersection(&ray_segment)
-        }
+                    .map(|position| (segment_idx, segment, position))
-        None
+            })
+            .min_by_key(|(_, _, position)| {
+                let offset = *position - ray_start;
+                let x = i128::from(offset.x.to_bits());
+                let y = i128::from(offset.y.to_bits());
+                x * x + y * y
+            })?;
+
+        Some(StagePlaneIntersectResult {
+            position,
+            segment_idx,
+            normal: segment.normal,
+        })
     }
 
     pub fn get_segment(&self, segment_idx: usize) -> Option<&StagePolyLineSegment> {
@@ -71,24 +83,65 @@ impl StagePoly {
     }
 
     pub fn get_next_segment(&self, segment_idx: usize) -> Option<&StagePolyLineSegment> {
-        self.segments.get(segment_idx % segment_idx + 1)
+        self.get_next_segment_index(segment_idx)
+            .and_then(|index| self.segments.get(index))
     }
 
     pub fn get_prev_segment(&self, segment_idx: usize) -> Option<&StagePolyLineSegment> {
-        self.segments.get(segment_idx % segment_idx + 1)
+        self.get_prev_segment_index(segment_idx)
+            .and_then(|index| self.segments.get(index))
     }
 
-    pub fn build(poly_type: StagePolyType, points: &[(Vec2, StagePolyLineSegmentType)]) -> Self {
+    pub fn get_next_segment_index(&self, segment_idx: usize) -> Option<usize> {
-        let windows = points.iter().zip(points.iter().cycle().skip(1));
+        if segment_idx >= self.segments.len() {
+            return None;
+        }
+
+        let next = segment_idx + 1;
+        if next < self.segments.len() {
+            Some(next)
+        } else if matches!(&self.poly_type, StagePolyType::Closed) {
+            Some(0)
+        } else {
+            None
+        }
+    }
+
+    pub fn get_prev_segment_index(&self, segment_idx: usize) -> Option<usize> {
+        if segment_idx >= self.segments.len() {
+            return None;
+        }
+
+        if segment_idx > 0 {
+            Some(segment_idx - 1)
+        } else if matches!(&self.poly_type, StagePolyType::Closed) {
+            self.segments.len().checked_sub(1)
+        } else {
+            None
+        }
+    }
+
+    pub fn build(poly_type: StagePolyType, points: &[(FGVec2, StagePolyLineSegmentType)]) -> Self {
+        let segment_count = if points.len() < 2 {
+            0
+        } else if matches!(&poly_type, StagePolyType::Closed) {
+            points.len()
+        } else {
+            points.len() - 1
+        };
+        let windows = points
+            .iter()
+            .zip(points.iter().cycle().skip(1))
+            .take(segment_count);
 
         let segments = windows.map(|segment_window| {
             let (first_point, segment_type) = segment_window.0;
             let (second_point, _) = segment_window.1;
-            let segment = Segment2d::new(*first_point, *second_point);
+            let segment = FGSegment2d::new(*first_point, *second_point);
             StagePolyLineSegment {
                 segment_type: *segment_type,
                 segment,
-                normal: segment.left_normal().as_vec2()
+                normal: segment.left_normal()
             }
         }).collect();
 
@@ -100,46 +153,97 @@ impl StagePoly {
 }
 
 impl StagePolyLineSegment {
-    pub fn project(&self, vec: Vec2) -> Vec2 {
+    pub fn project(&self, vec: FGVec2) -> FGVec2 {
         vec - vec.project_onto_normalized(self.normal)
     }
 }
 
 #[cfg(test)]
 mod tests {
+    use crate::math::int::FGi32;
+
     use super::*;
+
+    fn stage_segment(point1: FGVec2, point2: FGVec2) -> StagePolyLineSegment {
+        let segment = FGSegment2d::new(point1, point2);
+        StagePolyLineSegment {
+            segment,
+            normal: segment.left_normal(),
+            segment_type: StagePolyLineSegmentType::Floor,
+        }
+    }
+
+    #[test]
+    fn platform_is_open_and_closed_poly_wraps() {
+        let points = [
+            (FGVec2::lit("0", "0"), StagePolyLineSegmentType::Floor),
+            (FGVec2::lit("1", "0"), StagePolyLineSegmentType::Floor),
+            (FGVec2::lit("2", "0"), StagePolyLineSegmentType::Floor),
+        ];
+        let platform = StagePoly::build(StagePolyType::Platform, &points);
+        let closed = StagePoly::build(StagePolyType::Closed, &points);
+
+        assert_eq!(platform.segments.len(), 2);
+        assert_eq!(platform.get_next_segment_index(0), Some(1));
+        assert_eq!(platform.get_next_segment_index(1), None);
+        assert_eq!(platform.get_prev_segment_index(0), None);
+        assert_eq!(platform.get_prev_segment_index(1), Some(0));
+
+        assert_eq!(closed.segments.len(), 3);
+        assert_eq!(closed.get_next_segment_index(2), Some(0));
+        assert_eq!(closed.get_prev_segment_index(0), Some(2));
+    }
+
+    #[test]
+    fn ray_intersection_returns_nearest_hit() {
+        let stage_poly = StagePoly {
+            poly_type: StagePolyType::Platform,
+            segments: vec![
+                stage_segment(FGVec2::lit("-1", "0"), FGVec2::lit("1", "0")),
+                stage_segment(FGVec2::lit("-1", "1"), FGVec2::lit("1", "1")),
+            ],
+        };
+
+        let hit = stage_poly
+            .intersect_ray(FGSegment2d::new(FGVec2::lit("0", "2"), FGVec2::lit("0", "-1")))
+            .unwrap();
+
+        assert_eq!(hit.segment_idx, 1);
+        assert_eq!(hit.position, FGVec2::lit("0", "1"));
+    }
+
     #[test]
     fn ray_intersection_test() {
         let stage_poly = StagePoly::build(crate::stage::line::StagePolyType::Platform, &[
-            (Vec2::new(-4.5, 0.0), StagePolyLineSegmentType::Floor),
+            (FGVec2::lit("-4.5", "0.0"), StagePolyLineSegmentType::Floor),
-            (Vec2::new(4.5, 0.0), StagePolyLineSegmentType::Floor),
+            (FGVec2::lit("4.5", "0.0"), StagePolyLineSegmentType::Floor),
         ]);
 
-        let res = stage_poly.intersect_ray(Segment2d::new(Vec2::new(0.0, 1.0), Vec2::new(0.0, -1.0)));
+        let res = stage_poly.intersect_ray(FGSegment2d::new(FGVec2::lit("0.0", "1.0"), FGVec2::lit("0.0", "-1.0")));
         assert!(res.is_some());
-        assert_eq!(res.unwrap().position, Vec2::ZERO);
+        assert_eq!(res.unwrap().position, FGVec2::ZERO);
     }
 
     #[test]
     fn ray_intersection_test_side() {
         let stage_poly = StagePoly::build(crate::stage::line::StagePolyType::Platform, &[
-            (Vec2::new(-4.5, 0.0), StagePolyLineSegmentType::Floor),
+            (FGVec2::lit("-4.5", "0.0"), StagePolyLineSegmentType::Floor),
-            (Vec2::new(4.5, 0.0), StagePolyLineSegmentType::Floor),
+            (FGVec2::lit("4.5", "0.0"), StagePolyLineSegmentType::Floor),
         ]);
 
-        let res = stage_poly.intersect_ray(Segment2d::new(Vec2::new(2.0, 1.0), Vec2::new(2.0, -1.0)));
+        let res = stage_poly.intersect_ray(FGSegment2d::new(FGVec2::lit("2.0", "1.0"), FGVec2::lit("2.0", "-1.0")));
         assert!(res.is_some());
-        assert_eq!(res.unwrap().position, Vec2::new(2.0, 0.0));
+        assert!(res.unwrap().position.distance(FGVec2::lit("2.0", "0.0")) < FGi32::from_bits(4));
     }
     #[test]
     fn ray_intersection_test_diagonal() {
         let stage_poly = StagePoly::build(crate::stage::line::StagePolyType::Platform, &[
-            (Vec2::new(0.0, 0.0), StagePolyLineSegmentType::Floor),
+            (FGVec2::lit("0.0", "0.0"), StagePolyLineSegmentType::Floor),
-            (Vec2::new(2.0, 2.0), StagePolyLineSegmentType::Floor),
+            (FGVec2::lit("2.0", "2.0"), StagePolyLineSegmentType::Floor),
         ]);
 
-        let res = stage_poly.intersect_ray(Segment2d::new(Vec2::new(1.0, 2.0), Vec2::new(1.0, -2.0)));
+        let res = stage_poly.intersect_ray(FGSegment2d::new(FGVec2::lit("1.0", "2.0"), FGVec2::lit("1.0", "-2.0")));
         assert!(res.is_some());
-        assert_eq!(res.unwrap().position, Vec2::new(1.0, 1.0));
+        assert_eq!(res.unwrap().position, FGVec2::lit("1.0", "1.0"));
     }
-}
+}

src/stage/scene.rs

@@ -4,19 +4,19 @@ use std::f32::consts::PI;
 
 use bevy::{camera_controller::free_camera::FreeCamera, prelude::*};
 
-use crate::stage::{StagePoly, line::StagePolyLineSegmentType, line::StageCollision};
+use crate::{math::vec::FGVec2, stage::{StagePoly, line::{StageCollision, StagePolyLineSegmentType}}};
 
 /// set up a simple 3D scene
 pub fn test_scene() -> impl SceneList {
 
     let stage_poly = StagePoly::build(crate::stage::line::StagePolyType::Closed, &[
-        (Vec2::new(-5.6, -0.35), StagePolyLineSegmentType::Floor),
+        (FGVec2::lit("-5.6", "-0.35"), StagePolyLineSegmentType::Floor),
-        (Vec2::new(-3.92, 0.0), StagePolyLineSegmentType::Floor),
+        (FGVec2::lit("-3.92", "0.0"), StagePolyLineSegmentType::Floor),
-        (Vec2::new(0.0, 0.0), StagePolyLineSegmentType::Floor),
+        (FGVec2::lit("0.0", "0.0"), StagePolyLineSegmentType::Floor),
-        (Vec2::new(3.92, 0.0), StagePolyLineSegmentType::Floor),
+        (FGVec2::lit("3.92", "0.0"), StagePolyLineSegmentType::Floor),
-        (Vec2::new(5.6, -0.35), StagePolyLineSegmentType::Wall),
+        (FGVec2::lit("5.6", "-0.35"), StagePolyLineSegmentType::Wall),
-        (Vec2::new(5.6, -20.0), StagePolyLineSegmentType::Ceiling),
+        (FGVec2::lit("5.6", "-20.0"), StagePolyLineSegmentType::Ceiling),
-        (Vec2::new(-5.6, -20.0), StagePolyLineSegmentType::Wall)
+        (FGVec2::lit("-5.6", "-20.0"), StagePolyLineSegmentType::Wall)
     ]);
 
     bsn_list! [