avian3d-sandbox/src/physics.rs
2025-04-06 15:20:00 -07:00

395 lines
13 KiB
Rust

use avian3d::prelude::*;
use bevy::prelude::*;
#[derive(Resource, Default, Debug, Reflect)]
#[reflect(Resource)]
struct CyberLean {
pub lean: f32,
}
#[derive(Debug, Resource, Reflect)]
#[reflect(Resource)]
pub struct CatControllerSettings {
pub kp: f32,
pub kd: f32,
pub ki: f32,
}
impl Default for CatControllerSettings {
fn default() -> Self {
Self {
kp: 15.0,
kd: 1.5,
ki: 0.5,
}
}
}
#[derive(Component, Debug, Clone, Copy, Reflect)]
pub struct CatControllerState {
pub roll_integral: f32,
pub roll_prev: f32,
decay_factor: f32,
roll_limit: f32,
}
impl Default for CatControllerState {
fn default() -> Self {
Self {
roll_integral: Default::default(),
roll_prev: Default::default(),
decay_factor: 0.99,
roll_limit: 1.5,
}
}
}
impl CatControllerState {
pub fn update_roll(&mut self, error: f32, dt: f32) -> (f32, f32) {
let lim = self.roll_limit;
self.roll_integral = (self.roll_integral + (error * dt)).min(lim).max(-lim);
let derivative = (error - self.roll_prev) / dt;
self.roll_prev = error;
(derivative, self.roll_integral)
}
}
mod systems {
use std::f32::consts::{FRAC_PI_3, FRAC_PI_4};
use avian3d::prelude::*;
use bevy::prelude::*;
use super::{CatControllerSettings, CatControllerState, CyberLean};
use crate::{
bike::{CyberBikeBody, CyberWheel, WheelConfig, WheelState, WHEEL_RADIUS},
input::InputState,
};
fn rotate_point(pt: &Vec3, rot: &Quat) -> Vec3 {
// thanks to https://danceswithcode.net/engineeringnotes/quaternions/quaternions.html
let [x, y, z] = pt.normalize().to_array();
let qpt = Quat::from_xyzw(x, y, z, 0.0);
// p' = rot^-1 * qpt * rot
let rot_qpt = rot.inverse() * qpt * *rot;
// why does this need to be inverted???
-Vec3::from_array([rot_qpt.x, rot_qpt.y, rot_qpt.z])
}
pub(super) fn calculate_lean(
bike_state: Query<(&LinearVelocity, &Transform), With<CyberBikeBody>>,
wheels: Query<&GlobalTransform, With<CyberWheel>>,
input: Res<InputState>,
gravity: Res<Gravity>,
mut lean: ResMut<CyberLean>,
) {
let mut wheels = wheels.iter();
let w1 = wheels.next().unwrap();
let w2 = wheels.next().unwrap();
let base = (w1.translation() - w2.translation()).length().abs();
let (velocity, xform) = bike_state.single();
let vel = velocity.dot(*xform.forward());
let v_squared = vel.powi(2);
let steering_angle = yaw_to_angle(input.yaw);
let radius = base / steering_angle.tan();
let gravity = gravity.0.length();
let v2_r = v_squared / radius;
let tan_theta = (v2_r / gravity).clamp(-FRAC_PI_3, FRAC_PI_3);
if tan_theta.is_normal() {
lean.lean = tan_theta.atan().clamp(-FRAC_PI_3, FRAC_PI_3);
} else {
//lean.lean = 0.0;
}
}
pub(super) fn apply_lean(
mut bike_query: Query<(&Transform, &mut ExternalForce, &mut CatControllerState)>,
wheels: Query<&WheelState>,
time: Res<Time>,
settings: Res<CatControllerSettings>,
lean: Res<CyberLean>,
mut gizmos: Gizmos,
) {
let (xform, mut force, mut control_vars) = bike_query.single_mut();
let mut factor = 1.0;
for wheel in wheels.iter() {
if wheel.contact_point.is_none() {
factor -= 0.25;
}
}
let world_up = Vec3::Y; //xform.translation.normalize();
let rot = Quat::from_axis_angle(*xform.back(), lean.lean);
let target_up = rotate_point(&world_up, &rot).normalize();
// show which is up
gizmos.arrow(
xform.translation,
xform.translation + *xform.up(),
bevy::color::palettes::basic::YELLOW,
);
// show which is forward
gizmos.arrow(
*xform.forward() + xform.translation,
2.5 * *xform.forward() + xform.translation,
bevy::color::palettes::basic::PURPLE,
);
let bike_right = xform.right();
let roll_error = bike_right.dot(target_up);
let pitch_error = world_up.dot(*xform.back());
// only try to correct roll if we're not totally vertical
if pitch_error.abs() < 0.95 {
let (derivative, integral) = control_vars.update_roll(roll_error, time.delta_secs());
let mag =
(settings.kp * roll_error) + (settings.ki * integral) + (settings.kd * derivative);
if mag.is_finite() {
let lean_force = factor * mag * *xform.left();
force.apply_force_at_point(
lean_force,
xform.translation + *xform.up(),
xform.translation,
);
gizmos.arrow(
xform.translation + *xform.up(),
xform.translation + *xform.up() + lean_force,
Color::WHITE,
);
}
}
}
fn yaw_to_angle(yaw: f32) -> f32 {
let v = yaw.powi(5) * FRAC_PI_4;
if v.is_normal() {
v
} else {
0.0
}
}
pub(super) fn suspension(
mut bike_body_query: Query<(&Transform, &mut ExternalForce), With<CyberBikeBody>>,
mut wheel_mesh_query: Query<
(&mut Transform, &mut WheelState, &WheelConfig, &CyberWheel),
Without<CyberBikeBody>,
>,
caster_query: Query<(&RayCaster, &RayHits, &CyberWheel)>,
time: Res<Time>,
mut gizmos: Gizmos,
) {
let dt = time.delta().as_secs_f32();
let mut front_caster = &RayCaster::default();
let mut rear_caster = &RayCaster::default();
let mut front_hits = &RayHits::default();
let mut rear_hits = &RayHits::default();
for (caster, hits, wheel) in caster_query.iter() {
match wheel {
CyberWheel::Front => {
front_caster = caster;
front_hits = hits;
}
CyberWheel::Rear => {
rear_caster = caster;
rear_hits = hits;
}
}
}
let (bike_xform, mut bike_forces) = bike_body_query.single_mut();
for (mut xform, mut state, config, wheel) in wheel_mesh_query.iter_mut() {
let (caster, hits) = match wheel {
CyberWheel::Front => (front_caster, front_hits),
CyberWheel::Rear => (rear_caster, rear_hits),
};
if let Some(hit) = hits.iter().next() {
let dist = hit.distance;
let hit_point = caster.global_origin() + caster.global_direction() * dist;
let displacement = config.rest_dist - dist;
let damper_vel = (state.displacement - displacement) / dt;
let mag = config.konstant * displacement - config.damping * damper_vel;
let mag = mag.max(0.0);
state.force_normal = mag;
state.contact_normal = Some(hit.normal);
state.contact_point = Some(hit_point);
state.displacement = displacement;
let cdir = caster.direction.as_vec3();
xform.translation = config.attach + (cdir * (dist - WHEEL_RADIUS));
let force = hit.normal * mag * dt * 100.0;
gizmos.arrow(
hit_point,
hit_point + force,
Color::linear_rgb(1., 0.5, 0.2),
);
bike_forces.apply_force_at_point(
force,
caster.global_origin(),
bike_xform.translation,
);
} else {
xform.translation = config.attach + (caster.direction.as_vec3() * config.rest_dist);
state.reset();
}
}
}
pub(super) fn steering(
mut bike_query: Query<
(
&Transform,
&LinearVelocity,
&mut ExternalForce,
RigidBodyQueryReadOnly,
),
With<CyberBikeBody>,
>,
mut wheels: Query<(&mut WheelState, &WheelConfig, &CyberWheel)>,
time: Res<Time>,
input: Res<InputState>,
mut gizmos: Gizmos,
) {
let Ok((bike_xform, bike_vel, mut bike_force, bike_body)) = bike_query.get_single_mut()
else {
bevy::log::warn!("No entity for bike_query.");
return;
};
let bike_vel = bike_vel.0;
let dt = time.delta().as_secs_f32();
let max_thrust = 1000.0;
let yaw_angle = -yaw_to_angle(input.yaw);
for (mut state, config, wheel) in wheels.iter_mut() {
if let Some(contact_point) = state.contact_point {
// if contact_point is Some, we also have a normal.
let normal = state.contact_normal.unwrap().normalize();
let max_force_mag = state.force_normal * config.friction;
let rot = Quat::from_axis_angle(normal, yaw_angle);
let forward = normal.cross(*bike_xform.right());
let (thrust_dir, thrust_force) = match wheel {
CyberWheel::Rear => (forward, input.throttle * max_thrust * dt),
CyberWheel::Front => (rot * forward, 0.0),
};
let thrust = thrust_force * thrust_dir;
let friction_dir = match wheel {
CyberWheel::Front => normal.cross(thrust_dir),
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 mut force = thrust + friction;
force *= dt * 50.0;
let force_mag = force.length();
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;
}
bike_force.apply_force_at_point(force, contact_point, bike_xform.translation);
gizmos.arrow(
contact_point,
contact_point + friction,
Color::linear_rgb(1., 1., 0.2),
);
gizmos.arrow(
contact_point,
contact_point + thrust,
Color::linear_rgb(1., 0., 0.2),
);
}
}
}
pub(super) fn tweak(
mut config: Query<&mut WheelConfig>,
mut keys: ResMut<ButtonInput<KeyCode>>,
) {
let keyset: std::collections::HashSet<_> = keys.get_pressed().collect();
let shifted = keyset.contains(&KeyCode::ShiftLeft) || keyset.contains(&KeyCode::ShiftRight);
let config = config.iter_mut();
for ref mut c in config {
for key in &keyset {
match key {
KeyCode::KeyS => {
if shifted {
c.konstant += 0.2;
} else {
c.konstant -= 0.2;
}
bevy::log::info!(c.konstant);
}
KeyCode::KeyD => {
if shifted {
c.damping += 0.1;
} else {
c.damping -= 0.1;
}
bevy::log::info!(c.damping);
}
_ => continue,
}
}
}
let released: Vec<_> = keys.get_just_released().copied().collect();
for key in released {
keys.clear_just_released(key);
}
}
}
use systems::{apply_lean, calculate_lean, steering, suspension, tweak};
pub struct CyberPhysicsPlugin;
impl Plugin for CyberPhysicsPlugin {
fn build(&self, app: &mut App) {
app.init_resource::<CatControllerSettings>()
.register_type::<CatControllerSettings>()
.register_type::<CatControllerState>()
.init_resource::<CyberLean>()
.register_type::<CyberLean>()
.add_plugins((PhysicsPlugins::default(), PhysicsDebugPlugin::default()))
.insert_resource(SubstepCount(12))
.add_systems(Startup, |mut gravity: ResMut<Gravity>| {
gravity.0 *= 1.0;
})
.add_systems(
FixedUpdate,
(calculate_lean, apply_lean, suspension, steering).chain(),
)
.add_systems(Update, tweak);
}
}