Modified fixed_joint_2d example with rotation axes note

fixed_joint_2d.rs

use avian2d::{math::*, prelude::*};
use bevy::{ecs::component::StorageType, prelude::*};
use examples_common_2d::ExampleCommonPlugin;

fn main() {
    App::new()
        .add_plugins((
            DefaultPlugins,
            ExampleCommonPlugin,
            PhysicsPlugins::default(),
        ))
        .insert_resource(ClearColor(Color::srgb(0.05, 0.05, 0.1)))
        .insert_resource(SubstepCount(50))
        .insert_resource(Gravity(Vector::NEG_Y * 1000.0))
        .add_systems(Startup, setup)
        .run();
}

fn setup(mut commands: Commands) {
    commands.spawn(Camera2dBundle::default());

    let square_sprite = Sprite {
        color: Color::srgb(0.2, 0.7, 0.9),
        custom_size: Some(Vec2::splat(50.0)),
        ..default()
    };

    let square_sprite2 = Sprite {
        color: Color::srgb(1.0, 0.7, 0.9),
        custom_size: Some(Vec2::splat(50.0)),
        ..default()
    };

    let anchor = commands
        .spawn((
            SpriteBundle {
                sprite: square_sprite2.clone(),
                ..default()
            },
            RigidBody::Dynamic,
            AngularVelocity(1.5),
        ))
        .id();

    let object = commands
        .spawn((
            SpriteBundle {
                sprite: square_sprite,
                transform: Transform::from_xyz(100.0, 0.0, 0.0),
                ..default()
            },
            LockedAxes::ROTATION_LOCKED,
            RigidBody::Dynamic,
            MassPropertiesBundle::new_computed(&Collider::rectangle(50.0, 50.0), 1.0),
        ))
        .id();

    let joint_entity = commands
        .spawn(FixedJoint::new(anchor, object).with_local_anchor_1(Vector::X * 100.0))
        .id();

    commands.entity(object).insert(Docked {
        target: anchor,
        joint: joint_entity,
    });
}

#[derive(Debug, Reflect)]
pub struct Docked {
    pub target: Entity,
    pub joint: Entity,
}

// when Docked is added, we need to remove axis locks, so ship can rotate along with asteroid.
impl Component for Docked {
    const STORAGE_TYPE: StorageType = StorageType::Table;
    fn register_component_hooks(hooks: &mut bevy::ecs::component::ComponentHooks) {
        hooks.on_add(|mut world, entity, _component_id| {
            if let Some(locked_axes) = world.get_mut::<LockedAxes>(entity) {
                info!("Unlocking rotation for entity: {entity}");
                locked_axes.unlock_rotation();
            }
        });
        hooks.on_remove(|mut world, entity, _component_id| {
            if let Some(locked_axes) = world.get_mut::<LockedAxes>(entity) {
                info!("Locking rotation for entity: {entity}");
                locked_axes.lock_rotation();
            }
        });
    }
}

output:

Screen.Recording.2024-09-02.at.13.33.28.mov

ugh nevermind, just realised unlock_rotation() returns self! so it wasn't assigned to the component 😢

Jondolf/avian#506