add drag, bias power to front

src/bike.rs

@@ -6,13 +6,13 @@ use bevy::prelude::*;
 
 use crate::physics::CatControllerState;
 
-pub const SPRING_CONSTANT: Scalar = 50.0;
+pub const SPRING_CONSTANT: Scalar = 60.0;
 pub const DAMPING_CONSTANT: Scalar = 10.0;
 pub const WHEEL_RADIUS: Scalar = 0.4;
-pub const REST_DISTANCE: Scalar = 1.0 + WHEEL_RADIUS;
+pub const REST_DISTANCE: Scalar = 1.5 + WHEEL_RADIUS;
-pub const FRICTION_COEFF: Scalar = 0.8;
+pub const FRICTION_COEFF: Scalar = 0.9;
-pub const FRONT_ATTACH: Vec3 = Vec3::new(0.0, 0.0, -0.7);
+pub const FRONT_ATTACH: Vec3 = Vec3::new(0.0, 0.0, -0.5);
-pub const REAR_ATTACH: Vec3 = Vec3::new(0.0, 0.0, 0.7);
+pub const REAR_ATTACH: Vec3 = Vec3::new(0.0, 0.0, 0.5);
 
 #[derive(Component)]
 pub struct CyberBikeBody;
@@ -92,7 +92,7 @@ fn spawn_bike(
             SleepingDisabled,
             CyberBikeBody,
             CatControllerState::default(),
-            ColliderDensity(0.6),
+            ColliderDensity(1.2),
             AngularDamping(0.2),
             LinearDamping(0.1),
             ExternalForce::ZERO.with_persistence(false),
@@ -120,7 +120,7 @@ fn spawn_wheels(
 ) {
     let mesh: Mesh = Sphere::new(WHEEL_RADIUS).into();
 
-    let front_rake = Vec3::new(0.0, -1.0, -0.57).normalize(); // about 30 degrees
+    let front_rake = Vec3::new(0.0, -1.0, -0.9).normalize(); // about 30 degrees
     let front_wheel_pos = FRONT_ATTACH + (front_rake * REST_DISTANCE);
 
     wheel_caster(
@@ -148,7 +148,7 @@ fn spawn_wheels(
         CyberWheel::Front,
     );
 
-    let rear_rake = Vec3::new(0.0, -1.0, 0.57).normalize();
+    let rear_rake = Vec3::new(0.0, -1.0, 0.9).normalize();
     let rear_wheel_pos = REAR_ATTACH + (rear_rake * REST_DISTANCE);
 
     wheel_caster(

src/physics.rs

@@ -1,6 +1,8 @@
-use avian3d::prelude::*;
+use avian3d::{math::Scalar, prelude::*};
 use bevy::prelude::*;
 
+const DRAG_COEFF: Scalar = 0.1;
+
 #[derive(Resource, Default, Debug, Reflect)]
 #[reflect(Resource)]
 struct CyberLean {
@@ -18,9 +20,9 @@ pub struct CatControllerSettings {
 impl Default for CatControllerSettings {
     fn default() -> Self {
         Self {
-            kp: 15.0,
+            kp: 16.0,
-            kd: 1.5,
+            kd: 2.0,
-            ki: 0.5,
+            ki: 0.9,
         }
     }
 }
@@ -29,7 +31,6 @@ impl Default for CatControllerSettings {
 pub struct CatControllerState {
     pub roll_integral: f32,
     pub roll_prev: f32,
-    decay_factor: f32,
     roll_limit: f32,
 }
 
@@ -38,7 +39,6 @@ impl Default for CatControllerState {
         Self {
             roll_integral: Default::default(),
             roll_prev: Default::default(),
-            decay_factor: 0.99,
             roll_limit: 1.5,
         }
     }
@@ -60,7 +60,7 @@ mod systems {
     use avian3d::prelude::*;
     use bevy::prelude::*;
 
-    use super::{CatControllerSettings, CatControllerState, CyberLean};
+    use super::{CatControllerSettings, CatControllerState, CyberLean, DRAG_COEFF};
     use crate::{
         bike::{CyberBikeBody, CyberWheel, WheelConfig, WheelState, WHEEL_RADIUS},
         input::InputState,
@@ -272,7 +272,7 @@ mod systems {
         let bike_vel = bike_vel.0;
 
         let dt = time.delta().as_secs_f32();
-        let max_thrust = 1000.0;
+        let max_thrust = 2000.0;
         let yaw_angle = -yaw_to_angle(input.yaw);
 
         for (mut state, config, wheel) in wheels.iter_mut() {
@@ -283,9 +283,10 @@ mod systems {
 
                 let rot = Quat::from_axis_angle(normal, yaw_angle);
                 let forward = normal.cross(*bike_xform.right());
+                let thrust_mag = input.throttle * max_thrust * dt;
                 let (thrust_dir, thrust_force) = match wheel {
-                    CyberWheel::Rear => (forward, input.throttle * max_thrust * dt),
+                    CyberWheel::Rear => (forward, thrust_mag * 0.1),
-                    CyberWheel::Front => (rot * forward, 0.0),
+                    CyberWheel::Front => (rot * forward, thrust_mag),
                 };
 
                 let thrust = thrust_force * thrust_dir;
@@ -295,16 +296,12 @@ mod systems {
                     CyberWheel::Rear => normal.cross(*bike_xform.forward()),
                 };
 
-                // bevy::log::debug!(
-                //     "{wheel:?}, thrust_dir: {thrust_dir:?}, friction_dir: {friction_dir:?}, dot: {}",
-                //     thrust_dir.dot(friction_dir)
-                // );
-
                 let vel = bike_body.velocity_at_point(contact_point - bike_xform.translation);
                 let friction_factor = -0.025 * vel.dot(friction_dir);
                 let friction = (friction_factor / dt) * friction_dir;
 
-                bevy::log::debug!("{wheel:?}: vel diff: {:?}", bike_vel - vel);
+                let diff = bike_vel - vel;
+                bevy::log::debug!("{wheel:?}: vel diff: {diff:?} ({})", diff.length(),);
 
                 let mut force = thrust + friction;
                 force *= dt * 50.0;
@@ -312,7 +309,6 @@ mod systems {
                 if force_mag > max_force_mag {
                     state.sliding = true;
                     force = force.normalize_or_zero() * max_force_mag;
-                    //bevy::log::info!("clamping {wheel:?} to {max_force_mag}: {friction_factor}");
                 } else {
                     state.sliding = false;
                 }
@@ -332,6 +328,35 @@ mod systems {
         }
     }
 
+    pub(super) fn drag(
+        mut bike_query: Query<
+            (&Transform, &LinearVelocity, &mut ExternalForce),
+            With<CyberBikeBody>,
+        >,
+        mut gizmos: Gizmos,
+        time: Res<Time>,
+    ) {
+        let (xform, vel, mut force) = bike_query.single_mut();
+
+        let dt = time.delta_secs();
+
+        let speed = vel.length();
+        let dspeed = speed.powf(1.2) * 0.1;
+        let dir = vel.normalize_or_zero();
+        let drag = -dspeed * dt * DRAG_COEFF * dir;
+        if speed > 1.0 {
+            force.apply_force_at_point(drag, xform.translation, xform.translation);
+        }
+
+        bevy::log::debug!("speed: {}, drag force: {}", speed, drag.length());
+
+        gizmos.arrow(
+            xform.translation,
+            xform.translation + drag * 10.,
+            Color::linear_rgb(1.0, 0.0, 0.0),
+        );
+    }
+
     pub(super) fn tweak(
         mut config: Query<&mut WheelConfig>,
         mut keys: ResMut<ButtonInput<KeyCode>>,
@@ -370,7 +395,7 @@ mod systems {
     }
 }
 
-use systems::{apply_lean, calculate_lean, steering, suspension, tweak};
+use systems::{apply_lean, calculate_lean, drag, steering, suspension, tweak};
 
 pub struct CyberPhysicsPlugin;
 
@@ -388,7 +413,7 @@ impl Plugin for CyberPhysicsPlugin {
             })
             .add_systems(
                 FixedUpdate,
-                (calculate_lean, apply_lean, suspension, steering).chain(),
+                (calculate_lean, apply_lean, suspension, steering, drag).chain(),
             )
             .add_systems(Update, tweak);
     }