games/examples/sensors.rs

use bevy::{color::palettes::css::{BLUE, GREEN}, render::mesh::{SphereKind, SphereMeshBuilder}};
use bevy_rapier3d::rapier::prelude::CollisionEventFlags;
use games::*;

fn main() {
    App::new()
        .add_plugins(BaseGamePlugin)
        .add_systems(Startup, (
            setup_physics_scene,
            position_camera.after(setup_camera)
        ).chain())
        .add_systems(Update, (control_ball, read_events))
        .run();
}

fn setup_physics_scene(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<StandardMaterial>>
) {
    // Create the ground.
    // Make this a physical looking object
    commands
        .spawn((
            Collider::cuboid(100.0, 0.1, 100.0),
            Transform::from_xyz(0.0, -2.0, 0.0),
            Mesh3d(meshes.add(Plane3d::new(Vec3::Y, Vec2::splat(50.0)))),
            MeshMaterial3d(materials.add(StandardMaterial {
                base_color: RED.into(),
                ..Default::default()
            })),
        ));

    commands.spawn((
        SpotLight { color: WHITE.into(), intensity: 10_000_000.0, shadows_enabled: true, ..default() },
        Transform::from_xyz(0.0, 10.0, 10.0).looking_at(Vec3::ZERO, Vec3::Y),
    ));

    // Create the bouncing ball.
    commands
        .spawn((
            RigidBody::Dynamic,
            GravityScale(1.0),
            Collider::ball(0.5),
            ColliderMassProperties::Mass(2.0),
            Restitution::coefficient(0.7),
            ExternalImpulse::default(),
            Transform::from_xyz(0.0, 4.0, 0.0),
            Marker,
            ActiveEvents::all(),
            Mesh3d(meshes.add(SphereMeshBuilder::new(
                0.5,
                SphereKind::Uv {
                    sectors: 10,
                    stacks: 10,
                },
            ))),
            MeshMaterial3d(materials.add(StandardMaterial {
                base_color: BLUE.into(),
                ..Default::default()
            })),
        ));

    // Create a box that the ball can pass into/through
    // TODO: Transparent box to visualize area
    commands
        .spawn((
            Sensor,
            Marker,
            Collider::cuboid(1.0, 1.0, 1.0),
            Transform::from_xyz(0.0, 0.0, 0.0),
            Mesh3d(meshes.add(Cuboid::new(2.0, 2.0, 2.0))),
            MeshMaterial3d(materials.add(StandardMaterial {
                base_color: GREEN.with_alpha(0.5).into(),
                alpha_mode: AlphaMode::Blend,
                ..Default::default()
            })),
        ));
}

/// Position the world camera to get a better view
fn position_camera(
    mut query: Query<(Entity, &mut Transform), (With<Camera>, With<Camera3d>)>,
    mut commands: Commands,
) {
    query.iter_mut().for_each(|(e, mut t)| {
        *t = Transform::from_xyz(10.0, 10.0, 10.0)
            .looking_at(Vec3::ZERO, Vec3::Y);
    })
}

fn control_ball(
    keys: Res<ButtonInput<KeyCode>>,
    mut ball: Single<&mut ExternalImpulse>,
) {
    if keys.pressed(KeyCode::ArrowUp) {
        ball.torque_impulse = Vec3::new(0.0, 0.0, 0.1);
    }

    if keys.pressed(KeyCode::ArrowDown) {
        ball.torque_impulse = Vec3::new(0.0, 0.0, -0.1);
    }

    if keys.pressed(KeyCode::ArrowLeft) {
        ball.torque_impulse = Vec3::new(0.1, 0.0, 0.0);
    }

    if keys.pressed(KeyCode::ArrowRight) {
        ball.torque_impulse = Vec3::new(-0.1, 0.0, 0.0);
    }
}

#[derive(Debug)]
enum WithinBounds {
    Enter(Entity, Entity),
    Exit(Entity, Entity),
}

#[derive(Component, Debug)]
struct Marker;

fn read_events(
    mut events: EventReader<CollisionEvent>,
    mut commands: Commands,
) {
    events.read().filter_map(|collision_event| {
        match collision_event {
            CollisionEvent::Started(a, b, flags) => {
                (*flags == CollisionEventFlags::SENSOR).then_some(WithinBounds::Enter(*a, *b))
            },
            CollisionEvent::Stopped(a, b, flags) => {
                (*flags == CollisionEventFlags::SENSOR).then_some(WithinBounds::Exit(*a, *b))
            }
        }
    }).for_each(|within_bounds| {
        info!("Event: {:?}", within_bounds);
    })
}