Struct bevy::ecs::system::EntityCommands

pub struct EntityCommands<'a> { /* private fields */ }

A list of commands that will be run to modify an entity.

Implementations

impl EntityCommands<'_>

pub fn id(&self) -> Entity

Returns the Entity id of the entity.

Example

fn my_system(mut commands: Commands) {
    let entity_id = commands.spawn_empty().id();
}

Examples found in repository

examples/ecs/state.rs (line 91)

fn setup_menu(mut commands: Commands) {
    let button_entity = commands
        .spawn(NodeBundle {
            style: Style {
                // center button
                width: Val::Percent(100.),
                height: Val::Percent(100.),
                justify_content: JustifyContent::Center,
                align_items: AlignItems::Center,
                ..default()
            },
            ..default()
        })
        .with_children(|parent| {
            parent
                .spawn(ButtonBundle {
                    style: Style {
                        width: Val::Px(150.),
                        height: Val::Px(65.),
                        // horizontally center child text
                        justify_content: JustifyContent::Center,
                        // vertically center child text
                        align_items: AlignItems::Center,
                        ..default()
                    },
                    image: UiImage::default().with_color(NORMAL_BUTTON),
                    ..default()
                })
                .with_children(|parent| {
                    parent.spawn(TextBundle::from_section(
                        "Play",
                        TextStyle {
                            font_size: 40.0,
                            color: Color::srgb(0.9, 0.9, 0.9),
                            ..default()
                        },
                    ));
                });
        })
        .id();
    commands.insert_resource(MenuData { button_entity });
}

examples/ecs/hierarchy.rs (line 41)

fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
    commands.spawn(Camera2dBundle::default());
    let texture = asset_server.load("branding/icon.png");

    // Spawn a root entity with no parent
    let parent = commands
        .spawn(SpriteBundle {
            transform: Transform::from_scale(Vec3::splat(0.75)),
            texture: texture.clone(),
            ..default()
        })
        // With that entity as a parent, run a lambda that spawns its children
        .with_children(|parent| {
            // parent is a ChildBuilder, which has a similar API to Commands
            parent.spawn(SpriteBundle {
                transform: Transform::from_xyz(250.0, 0.0, 0.0).with_scale(Vec3::splat(0.75)),
                texture: texture.clone(),
                sprite: Sprite {
                    color: BLUE.into(),
                    ..default()
                },
                ..default()
            });
        })
        // Store parent entity for next sections
        .id();

    // Another way is to use the push_children function to add children after the parent
    // entity has already been spawned.
    let child = commands
        .spawn(SpriteBundle {
            transform: Transform::from_xyz(0.0, 250.0, 0.0).with_scale(Vec3::splat(0.75)),
            texture,
            sprite: Sprite {
                color: LIME.into(),
                ..default()
            },
            ..default()
        })
        .id();

    // Add child to the parent.
    commands.entity(parent).add_child(child);
}

examples/ecs/sub_states.rs (line 225)

    pub fn setup_menu(mut commands: Commands) {
        let button_entity = commands
            .spawn(NodeBundle {
                style: Style {
                    // center button
                    width: Val::Percent(100.),
                    height: Val::Percent(100.),
                    justify_content: JustifyContent::Center,
                    align_items: AlignItems::Center,
                    ..default()
                },
                ..default()
            })
            .with_children(|parent| {
                parent
                    .spawn(ButtonBundle {
                        style: Style {
                            width: Val::Px(150.),
                            height: Val::Px(65.),
                            // horizontally center child text
                            justify_content: JustifyContent::Center,
                            // vertically center child text
                            align_items: AlignItems::Center,
                            ..default()
                        },
                        image: UiImage::default().with_color(NORMAL_BUTTON),
                        ..default()
                    })
                    .with_children(|parent| {
                        parent.spawn(TextBundle::from_section(
                            "Play",
                            TextStyle {
                                font_size: 40.0,
                                color: Color::srgb(0.9, 0.9, 0.9),
                                ..default()
                            },
                        ));
                    });
            })
            .id();
        commands.insert_resource(MenuData { button_entity });
    }

examples/window/multiple_windows.rs (line 30)

fn setup_scene(mut commands: Commands, asset_server: Res<AssetServer>) {
    // add entities to the world
    commands.spawn(SceneBundle {
        scene: asset_server.load("models/torus/torus.gltf#Scene0"),
        ..default()
    });
    // light
    commands.spawn(DirectionalLightBundle {
        transform: Transform::from_xyz(3.0, 3.0, 3.0).looking_at(Vec3::ZERO, Vec3::Y),
        ..default()
    });

    let first_window_camera = commands
        .spawn(Camera3dBundle {
            transform: Transform::from_xyz(0.0, 0.0, 6.0).looking_at(Vec3::ZERO, Vec3::Y),
            ..default()
        })
        .id();

    // Spawn a second window
    let second_window = commands
        .spawn(Window {
            title: "Second window".to_owned(),
            ..default()
        })
        .id();

    let second_window_camera = commands
        .spawn(Camera3dBundle {
            transform: Transform::from_xyz(6.0, 0.0, 0.0).looking_at(Vec3::ZERO, Vec3::Y),
            camera: Camera {
                target: RenderTarget::Window(WindowRef::Entity(second_window)),
                ..default()
            },
            ..default()
        })
        .id();

    // Since we are using multiple cameras, we need to specify which camera UI should be rendered to
    commands
        .spawn((NodeBundle::default(), TargetCamera(first_window_camera)))
        .with_children(|parent| {
            parent.spawn(TextBundle::from_section(
                "First window",
                TextStyle::default(),
            ));
        });
    commands
        .spawn((NodeBundle::default(), TargetCamera(second_window_camera)))
        .with_children(|parent| {
            parent.spawn(TextBundle::from_section(
                "Second window",
                TextStyle::default(),
            ));
        });
}

examples/games/contributors.rs (line 121)

fn setup_contributor_selection(mut commands: Commands, asset_server: Res<AssetServer>) {
    // Load contributors from the git history log or use default values from
    // the constant array. Contributors are stored in a HashMap with their
    // commit count.
    let contribs = contributors().unwrap_or_else(|_| {
        CONTRIBUTORS_LIST
            .iter()
            .map(|name| (name.to_string(), 1))
            .collect()
    });

    let texture_handle = asset_server.load("branding/icon.png");

    let mut contributor_selection = ContributorSelection {
        order: Vec::with_capacity(contribs.len()),
        idx: 0,
    };

    let mut rng = rand::thread_rng();

    for (name, num_commits) in contribs {
        let transform =
            Transform::from_xyz(rng.gen_range(-400.0..400.0), rng.gen_range(0.0..400.0), 0.0);
        let dir = rng.gen_range(-1.0..1.0);
        let velocity = Vec3::new(dir * 500.0, 0.0, 0.0);
        let hue = name_to_hue(&name);

        // Some sprites should be flipped for variety
        let flipped = rng.gen();

        let entity = commands
            .spawn((
                Contributor {
                    name,
                    num_commits,
                    hue,
                },
                Velocity {
                    translation: velocity,
                    rotation: -dir * 5.0,
                },
                SpriteBundle {
                    sprite: Sprite {
                        custom_size: Some(Vec2::splat(SPRITE_SIZE)),
                        color: DESELECTED.with_hue(hue).into(),
                        flip_x: flipped,
                        ..default()
                    },
                    texture: texture_handle.clone(),
                    transform,
                    ..default()
                },
            ))
            .id();

        contributor_selection.order.push(entity);
    }

    contributor_selection.order.shuffle(&mut rng);

    commands.insert_resource(contributor_selection);
}

examples/async_tasks/async_compute.rs (line 61)

fn spawn_tasks(mut commands: Commands) {
    let thread_pool = AsyncComputeTaskPool::get();
    for x in 0..NUM_CUBES {
        for y in 0..NUM_CUBES {
            for z in 0..NUM_CUBES {
                // Spawn new task on the AsyncComputeTaskPool; the task will be
                // executed in the background, and the Task future returned by
                // spawn() can be used to poll for the result
                let entity = commands.spawn_empty().id();
                let task = thread_pool.spawn(async move {
                    let mut rng = rand::thread_rng();

                    let duration = Duration::from_secs_f32(rng.gen_range(0.05..0.2));

                    // Pretend this is a time-intensive function. :)
                    thread::sleep(duration);

                    // Such hard work, all done!
                    let transform = Transform::from_xyz(x as f32, y as f32, z as f32);
                    let mut command_queue = CommandQueue::default();

                    // we use a raw command queue to pass a FnOne(&mut World) back to be
                    // applied in a deferred manner.
                    command_queue.push(move |world: &mut World| {
                        let (box_mesh_handle, box_material_handle) = {
                            let mut system_state = SystemState::<(
                                Res<BoxMeshHandle>,
                                Res<BoxMaterialHandle>,
                            )>::new(world);
                            let (box_mesh_handle, box_material_handle) =
                                system_state.get_mut(world);

                            (box_mesh_handle.clone(), box_material_handle.clone())
                        };

                        world
                            .entity_mut(entity)
                            // Add our new PbrBundle of components to our tagged entity
                            .insert(PbrBundle {
                                mesh: box_mesh_handle,
                                material: box_material_handle,
                                transform,
                                ..default()
                            })
                            // Task is complete, so remove task component from entity
                            .remove::<ComputeTransform>();
                    });

                    command_queue
                });

                // Spawn new entity and add our new task as a component
                commands.entity(entity).insert(ComputeTransform(task));
            }
        }
    }
}

Additional examples can be found in:

• examples/animation/animation_graph.rs
• examples/3d/irradiance_volumes.rs
• examples/games/alien_cake_addict.rs
• examples/stress_tests/transform_hierarchy.rs
• examples/ui/render_ui_to_texture.rs
• examples/ecs/computed_states.rs
• examples/ui/text_wrap_debug.rs
• examples/stress_tests/many_foxes.rs
• examples/animation/custom_skinned_mesh.rs
• examples/ui/borders.rs
• examples/3d/split_screen.rs
• examples/ui/rounded_borders.rs
• examples/ui/display_and_visibility.rs
• examples/ui/text_debug.rs
• examples/animation/animated_transform.rs
• examples/3d/blend_modes.rs

pub fn reborrow(&mut self) -> EntityCommands<'_>

Returns an EntityCommands with a smaller lifetime. This is useful if you have &mut EntityCommands but you need EntityCommands.

pub fn insert(&mut self, bundle: impl Bundle) -> &mut EntityCommands<'_>

Adds a Bundle of components to the entity.

This will overwrite any previous value(s) of the same component type.

Panics

The command will panic when applied if the associated entity does not exist.

To avoid a panic in this case, use the command Self::try_insert instead.

Example

#[derive(Component)]
struct Health(u32);
#[derive(Component)]
struct Strength(u32);
#[derive(Component)]
struct Defense(u32);

#[derive(Bundle)]
struct CombatBundle {
    health: Health,
    strength: Strength,
}

fn add_combat_stats_system(mut commands: Commands, player: Res<PlayerEntity>) {
    commands
        .entity(player.entity)
        // You can insert individual components:
        .insert(Defense(10))
        // You can also insert pre-defined bundles of components:
        .insert(CombatBundle {
            health: Health(100),
            strength: Strength(40),
        })
        // You can also insert tuples of components and bundles.
        // This is equivalent to the calls above:
        .insert((
            Defense(10),
            CombatBundle {
                health: Health(100),
                strength: Strength(40),
            },
        ));
}

Examples found in repository

examples/3d/irradiance_volumes.rs (lines 241-244)

fn spawn_camera(commands: &mut Commands, assets: &ExampleAssets) {
    commands
        .spawn(Camera3dBundle {
            transform: Transform::from_xyz(-10.012, 4.8605, 13.281).looking_at(Vec3::ZERO, Vec3::Y),
            ..default()
        })
        .insert(Skybox {
            image: assets.skybox.clone(),
            brightness: 150.0,
        });
}

fn spawn_irradiance_volume(commands: &mut Commands, assets: &ExampleAssets) {
    commands
        .spawn(SpatialBundle {
            transform: Transform::from_matrix(VOXEL_TRANSFORM),
            ..SpatialBundle::default()
        })
        .insert(IrradianceVolume {
            voxels: assets.irradiance_volume.clone(),
            intensity: IRRADIANCE_VOLUME_INTENSITY,
        })
        .insert(LightProbe);
}

fn spawn_light(commands: &mut Commands) {
    commands.spawn(PointLightBundle {
        point_light: PointLight {
            intensity: 250000.0,
            shadows_enabled: true,
            ..default()
        },
        transform: Transform::from_xyz(4.0762, 5.9039, 1.0055),
        ..default()
    });
}

fn spawn_sphere(commands: &mut Commands, assets: &ExampleAssets) {
    commands
        .spawn(PbrBundle {
            mesh: assets.main_sphere.clone(),
            material: assets.main_sphere_material.clone(),
            transform: Transform::from_xyz(0.0, SPHERE_SCALE, 0.0)
                .with_scale(Vec3::splat(SPHERE_SCALE)),
            ..default()
        })
        .insert(MainObject);
}

fn spawn_voxel_cube_parent(commands: &mut Commands) {
    commands
        .spawn(SpatialBundle {
            visibility: Visibility::Hidden,
            ..default()
        })
        .insert(VoxelCubeParent);
}

fn spawn_fox(commands: &mut Commands, assets: &ExampleAssets) {
    commands
        .spawn(SceneBundle {
            scene: assets.fox.clone(),
            visibility: Visibility::Hidden,
            transform: Transform::from_scale(Vec3::splat(FOX_SCALE)),
            ..default()
        })
        .insert(MainObject);
}

fn spawn_text(commands: &mut Commands, app_status: &AppStatus, asset_server: &AssetServer) {
    commands.spawn(
        TextBundle {
            text: app_status.create_text(asset_server),
            ..TextBundle::default()
        }
        .with_style(Style {
            position_type: PositionType::Absolute,
            bottom: Val::Px(10.0),
            left: Val::Px(10.0),
            ..default()
        }),
    );
}

// A system that updates the help text.
fn update_text(
    mut text_query: Query<&mut Text>,
    app_status: Res<AppStatus>,
    asset_server: Res<AssetServer>,
) {
    for mut text in text_query.iter_mut() {
        *text = app_status.create_text(&asset_server);
    }
}

impl AppStatus {
    // Constructs the help text at the bottom of the screen based on the
    // application status.
    fn create_text(&self, asset_server: &AssetServer) -> Text {
        let irradiance_volume_help_text = if self.irradiance_volume_present {
            DISABLE_IRRADIANCE_VOLUME_HELP_TEXT
        } else {
            ENABLE_IRRADIANCE_VOLUME_HELP_TEXT
        };

        let voxels_help_text = if self.voxels_visible {
            HIDE_VOXELS_HELP_TEXT
        } else {
            SHOW_VOXELS_HELP_TEXT
        };

        let rotation_help_text = if self.rotating {
            STOP_ROTATION_HELP_TEXT
        } else {
            START_ROTATION_HELP_TEXT
        };

        let switch_mesh_help_text = match self.model {
            ExampleModel::Sphere => SWITCH_TO_FOX_HELP_TEXT,
            ExampleModel::Fox => SWITCH_TO_SPHERE_HELP_TEXT,
        };

        Text::from_section(
            format!(
                "{}\n{}\n{}\n{}\n{}",
                CLICK_TO_MOVE_HELP_TEXT,
                voxels_help_text,
                irradiance_volume_help_text,
                rotation_help_text,
                switch_mesh_help_text
            ),
            TextStyle {
                font: asset_server.load("fonts/FiraMono-Medium.ttf"),
                font_size: 24.0,
                ..default()
            },
        )
    }
}

// Rotates the camera a bit every frame.
fn rotate_camera(
    mut camera_query: Query<&mut Transform, With<Camera3d>>,
    time: Res<Time>,
    app_status: Res<AppStatus>,
) {
    if !app_status.rotating {
        return;
    }

    for mut transform in camera_query.iter_mut() {
        transform.translation = Vec2::from_angle(ROTATION_SPEED * time.delta_seconds())
            .rotate(transform.translation.xz())
            .extend(transform.translation.y)
            .xzy();
        transform.look_at(Vec3::ZERO, Vec3::Y);
    }
}

// Toggles between the unskinned sphere model and the skinned fox model if the
// user requests it.
fn change_main_object(
    keyboard: Res<ButtonInput<KeyCode>>,
    mut app_status: ResMut<AppStatus>,
    mut sphere_query: Query<
        &mut Visibility,
        (With<MainObject>, With<Handle<Mesh>>, Without<Handle<Scene>>),
    >,
    mut fox_query: Query<&mut Visibility, (With<MainObject>, With<Handle<Scene>>)>,
) {
    if !keyboard.just_pressed(KeyCode::Tab) {
        return;
    }
    let Some(mut sphere_visibility) = sphere_query.iter_mut().next() else {
        return;
    };
    let Some(mut fox_visibility) = fox_query.iter_mut().next() else {
        return;
    };

    match app_status.model {
        ExampleModel::Sphere => {
            *sphere_visibility = Visibility::Hidden;
            *fox_visibility = Visibility::Visible;
            app_status.model = ExampleModel::Fox;
        }
        ExampleModel::Fox => {
            *sphere_visibility = Visibility::Visible;
            *fox_visibility = Visibility::Hidden;
            app_status.model = ExampleModel::Sphere;
        }
    }
}

impl Default for AppStatus {
    fn default() -> Self {
        Self {
            irradiance_volume_present: true,
            rotating: true,
            model: ExampleModel::Sphere,
            voxels_visible: false,
        }
    }
}

// Turns on and off the irradiance volume as requested by the user.
fn toggle_irradiance_volumes(
    mut commands: Commands,
    keyboard: Res<ButtonInput<KeyCode>>,
    light_probe_query: Query<Entity, With<LightProbe>>,
    mut app_status: ResMut<AppStatus>,
    assets: Res<ExampleAssets>,
    mut ambient_light: ResMut<AmbientLight>,
) {
    if !keyboard.just_pressed(KeyCode::Space) {
        return;
    };

    let Some(light_probe) = light_probe_query.iter().next() else {
        return;
    };

    if app_status.irradiance_volume_present {
        commands.entity(light_probe).remove::<IrradianceVolume>();
        ambient_light.brightness = AMBIENT_LIGHT_BRIGHTNESS * IRRADIANCE_VOLUME_INTENSITY;
        app_status.irradiance_volume_present = false;
    } else {
        commands.entity(light_probe).insert(IrradianceVolume {
            voxels: assets.irradiance_volume.clone(),
            intensity: IRRADIANCE_VOLUME_INTENSITY,
        });
        ambient_light.brightness = 0.0;
        app_status.irradiance_volume_present = true;
    }
}

fn toggle_rotation(keyboard: Res<ButtonInput<KeyCode>>, mut app_status: ResMut<AppStatus>) {
    if keyboard.just_pressed(KeyCode::Enter) {
        app_status.rotating = !app_status.rotating;
    }
}

// Handles clicks on the plane that reposition the object.
fn handle_mouse_clicks(
    buttons: Res<ButtonInput<MouseButton>>,
    windows: Query<&Window, With<PrimaryWindow>>,
    cameras: Query<(&Camera, &GlobalTransform)>,
    mut main_objects: Query<&mut Transform, With<MainObject>>,
) {
    if !buttons.pressed(MouseButton::Left) {
        return;
    }
    let Some(mouse_position) = windows
        .iter()
        .next()
        .and_then(|window| window.cursor_position())
    else {
        return;
    };
    let Some((camera, camera_transform)) = cameras.iter().next() else {
        return;
    };

    // Figure out where the user clicked on the plane.
    let Some(ray) = camera.viewport_to_world(camera_transform, mouse_position) else {
        return;
    };
    let Some(ray_distance) = ray.intersect_plane(Vec3::ZERO, InfinitePlane3d::new(Vec3::Y)) else {
        return;
    };
    let plane_intersection = ray.origin + ray.direction.normalize() * ray_distance;

    // Move all the main objeccts.
    for mut transform in main_objects.iter_mut() {
        transform.translation = vec3(
            plane_intersection.x,
            transform.translation.y,
            plane_intersection.z,
        );
    }
}

impl FromWorld for ExampleAssets {
    fn from_world(world: &mut World) -> Self {
        let fox_animation = world.load_asset("models/animated/Fox.glb#Animation1");
        let (fox_animation_graph, fox_animation_node) =
            AnimationGraph::from_clip(fox_animation.clone());

        ExampleAssets {
            main_sphere: world.add_asset(Sphere::default().mesh().uv(32, 18)),
            fox: world.load_asset("models/animated/Fox.glb#Scene0"),
            main_sphere_material: world.add_asset(Color::from(SILVER)),
            main_scene: world
                .load_asset("models/IrradianceVolumeExample/IrradianceVolumeExample.glb#Scene0"),
            irradiance_volume: world.load_asset("irradiance_volumes/Example.vxgi.ktx2"),
            fox_animation_graph: world.add_asset(fox_animation_graph),
            fox_animation_node,
            voxel_cube: world.add_asset(Cuboid::default()),
            // Just use a specular map for the skybox since it's not too blurry.
            // In reality you wouldn't do this--you'd use a real skybox texture--but
            // reusing the textures like this saves space in the Bevy repository.
            skybox: world.load_asset("environment_maps/pisa_specular_rgb9e5_zstd.ktx2"),
        }
    }
}

// Plays the animation on the fox.
fn play_animations(
    mut commands: Commands,
    assets: Res<ExampleAssets>,
    mut players: Query<(Entity, &mut AnimationPlayer), Without<Handle<AnimationGraph>>>,
) {
    for (entity, mut player) in players.iter_mut() {
        commands
            .entity(entity)
            .insert(assets.fox_animation_graph.clone());
        player.play(assets.fox_animation_node).repeat();
    }
}

fn create_cubes(
    image_assets: Res<Assets<Image>>,
    mut commands: Commands,
    irradiance_volumes: Query<(&IrradianceVolume, &GlobalTransform)>,
    voxel_cube_parents: Query<Entity, With<VoxelCubeParent>>,
    voxel_cubes: Query<Entity, With<VoxelCube>>,
    example_assets: Res<ExampleAssets>,
    mut voxel_visualization_material_assets: ResMut<Assets<VoxelVisualizationMaterial>>,
) {
    // If voxel cubes have already been spawned, don't do anything.
    if !voxel_cubes.is_empty() {
        return;
    }

    let Some(voxel_cube_parent) = voxel_cube_parents.iter().next() else {
        return;
    };

    for (irradiance_volume, global_transform) in irradiance_volumes.iter() {
        let Some(image) = image_assets.get(&irradiance_volume.voxels) else {
            continue;
        };

        let resolution = image.texture_descriptor.size;

        let voxel_cube_material = voxel_visualization_material_assets.add(ExtendedMaterial {
            base: StandardMaterial::from(Color::from(RED)),
            extension: VoxelVisualizationExtension {
                irradiance_volume_info: VoxelVisualizationIrradianceVolumeInfo {
                    transform: VOXEL_TRANSFORM.inverse(),
                    inverse_transform: VOXEL_TRANSFORM,
                    resolution: uvec3(
                        resolution.width,
                        resolution.height,
                        resolution.depth_or_array_layers,
                    ),
                    intensity: IRRADIANCE_VOLUME_INTENSITY,
                },
            },
        });

        let scale = vec3(
            1.0 / resolution.width as f32,
            1.0 / resolution.height as f32,
            1.0 / resolution.depth_or_array_layers as f32,
        );

        // Spawn a cube for each voxel.
        for z in 0..resolution.depth_or_array_layers {
            for y in 0..resolution.height {
                for x in 0..resolution.width {
                    let uvw = (uvec3(x, y, z).as_vec3() + 0.5) * scale - 0.5;
                    let pos = global_transform.transform_point(uvw);
                    let voxel_cube = commands
                        .spawn(MaterialMeshBundle {
                            mesh: example_assets.voxel_cube.clone(),
                            material: voxel_cube_material.clone(),
                            transform: Transform::from_scale(Vec3::splat(VOXEL_CUBE_SCALE))
                                .with_translation(pos),
                            ..default()
                        })
                        .insert(VoxelCube)
                        .insert(NotShadowCaster)
                        .id();

                    commands.entity(voxel_cube_parent).add_child(voxel_cube);
                }
            }
        }
    }
}

examples/3d/reflection_probes.rs (line 186)

fn add_environment_map_to_camera(
    mut commands: Commands,
    query: Query<Entity, Added<Camera3d>>,
    cubemaps: Res<Cubemaps>,
) {
    for camera_entity in query.iter() {
        commands
            .entity(camera_entity)
            .insert(create_camera_environment_map_light(&cubemaps))
            .insert(Skybox {
                image: cubemaps.skybox.clone(),
                brightness: 5000.0,
            });
    }
}

// A system that handles switching between different reflection modes.
fn change_reflection_type(
    mut commands: Commands,
    light_probe_query: Query<Entity, With<LightProbe>>,
    camera_query: Query<Entity, With<Camera3d>>,
    keyboard: Res<ButtonInput<KeyCode>>,
    mut app_status: ResMut<AppStatus>,
    cubemaps: Res<Cubemaps>,
) {
    // Only do anything if space was pressed.
    if !keyboard.just_pressed(KeyCode::Space) {
        return;
    }

    // Switch reflection mode.
    app_status.reflection_mode =
        ReflectionMode::try_from((app_status.reflection_mode as u32 + 1) % 3).unwrap();

    // Add or remove the light probe.
    for light_probe in light_probe_query.iter() {
        commands.entity(light_probe).despawn();
    }
    match app_status.reflection_mode {
        ReflectionMode::None | ReflectionMode::EnvironmentMap => {}
        ReflectionMode::ReflectionProbe => spawn_reflection_probe(&mut commands, &cubemaps),
    }

    // Add or remove the environment map from the camera.
    for camera in camera_query.iter() {
        match app_status.reflection_mode {
            ReflectionMode::None => {
                commands.entity(camera).remove::<EnvironmentMapLight>();
            }
            ReflectionMode::EnvironmentMap | ReflectionMode::ReflectionProbe => {
                commands
                    .entity(camera)
                    .insert(create_camera_environment_map_light(&cubemaps));
            }
        }
    }
}

examples/ecs/one_shot_systems.rs (line 64)

fn trigger_system(
    mut commands: Commands,
    query_a: Query<Entity, With<A>>,
    query_b: Query<Entity, With<B>>,
    input: Res<ButtonInput<KeyCode>>,
) {
    if input.just_pressed(KeyCode::KeyA) {
        let entity = query_a.single();
        commands.entity(entity).insert(Triggered);
    }
    if input.just_pressed(KeyCode::KeyB) {
        let entity = query_b.single();
        commands.entity(entity).insert(Triggered);
    }
}

examples/asset/asset_decompression.rs (line 132)

fn decompress<A: Asset>(
    mut commands: Commands,
    asset_server: Res<AssetServer>,
    mut compressed_assets: ResMut<Assets<GzAsset>>,
    query: Query<(Entity, &Compressed<A>)>,
) {
    for (entity, Compressed { compressed, .. }) in query.iter() {
        let Some(GzAsset { uncompressed }) = compressed_assets.remove(compressed) else {
            continue;
        };

        let uncompressed = uncompressed.take::<A>().unwrap();

        commands
            .entity(entity)
            .remove::<Compressed<A>>()
            .insert(asset_server.add(uncompressed));
    }
}

examples/shader/shader_instancing.rs (lines 170-173)

fn prepare_instance_buffers(
    mut commands: Commands,
    query: Query<(Entity, &InstanceMaterialData)>,
    render_device: Res<RenderDevice>,
) {
    for (entity, instance_data) in &query {
        let buffer = render_device.create_buffer_with_data(&BufferInitDescriptor {
            label: Some("instance data buffer"),
            contents: bytemuck::cast_slice(instance_data.as_slice()),
            usage: BufferUsages::VERTEX | BufferUsages::COPY_DST,
        });
        commands.entity(entity).insert(InstanceBuffer {
            buffer,
            length: instance_data.len(),
        });
    }
}

examples/stress_tests/many_foxes.rs (line 245)

fn setup_scene_once_loaded(
    animations: Res<Animations>,
    foxes: Res<Foxes>,
    mut commands: Commands,
    mut player: Query<(Entity, &mut AnimationPlayer)>,
    mut done: Local<bool>,
) {
    if !*done && player.iter().len() == foxes.count {
        for (entity, mut player) in &mut player {
            commands
                .entity(entity)
                .insert(animations.graph.clone())
                .insert(AnimationTransitions::new());

            let playing_animation = player.play(animations.node_indices[0]).repeat();
            if !foxes.sync {
                playing_animation.seek_to(entity.index() as f32 / 10.0);
            }
        }
        *done = true;
    }
}

Additional examples can be found in:

• examples/animation/morph_targets.rs
• examples/animation/animated_fox.rs
• examples/games/game_menu.rs
• examples/3d/clearcoat.rs
• examples/3d/shadow_caster_receiver.rs
• examples/games/stepping.rs
• examples/stress_tests/many_buttons.rs
• examples/3d/tonemapping.rs
• examples/3d/color_grading.rs
• examples/3d/lightmaps.rs
• examples/audio/soundtrack.rs
• examples/ui/relative_cursor_position.rs
• examples/2d/bounding_2d.rs
• examples/3d/visibility_range.rs
• examples/3d/anti_aliasing.rs
• examples/3d/ssao.rs
• examples/3d/motion_blur.rs
• examples/async_tasks/async_compute.rs
• examples/animation/animation_graph.rs
• examples/stress_tests/transform_hierarchy.rs
• examples/3d/deferred_rendering.rs
• examples/2d/sprite_slice.rs
• examples/tools/scene_viewer/animation_plugin.rs
• examples/3d/bloom_3d.rs
• examples/2d/bloom_2d.rs
• examples/animation/animated_transform.rs
• examples/stress_tests/many_cubes.rs
• examples/3d/transmission.rs

pub fn try_insert(&mut self, bundle: impl Bundle) -> &mut EntityCommands<'_>

Tries to add a Bundle of components to the entity.

This will overwrite any previous value(s) of the same component type.

Note

Unlike Self::insert, this will not panic if the associated entity does not exist.

Example

#[derive(Component)]
struct Health(u32);
#[derive(Component)]
struct Strength(u32);
#[derive(Component)]
struct Defense(u32);

#[derive(Bundle)]
struct CombatBundle {
    health: Health,
    strength: Strength,
}

fn add_combat_stats_system(mut commands: Commands, player: Res<PlayerEntity>) {
  commands.entity(player.entity)
   // You can try_insert individual components:
    .try_insert(Defense(10))

   // You can also insert tuples of components:
    .try_insert(CombatBundle {
        health: Health(100),
        strength: Strength(40),
    });

   // Suppose this occurs in a parallel adjacent system or process
   commands.entity(player.entity)
     .despawn();

   commands.entity(player.entity)
   // This will not panic nor will it add the component
     .try_insert(Defense(5));
}

pub fn remove<T>(&mut self) -> &mut EntityCommands<'_>

where T: Bundle,

Removes a Bundle of components from the entity.

Example

#[derive(Component)]
struct Health(u32);
#[derive(Component)]
struct Strength(u32);
#[derive(Component)]
struct Defense(u32);

#[derive(Bundle)]
struct CombatBundle {
    health: Health,
    strength: Strength,
}

fn remove_combat_stats_system(mut commands: Commands, player: Res<PlayerEntity>) {
    commands
        .entity(player.entity)
        // You can remove individual components:
        .remove::<Defense>()
        // You can also remove pre-defined Bundles of components:
        .remove::<CombatBundle>()
        // You can also remove tuples of components and bundles.
        // This is equivalent to the calls above:
        .remove::<(Defense, CombatBundle)>();
}

Examples found in repository

examples/ecs/one_shot_systems.rs (line 78)

fn evaluate_callbacks(query: Query<(Entity, &Callback), With<Triggered>>, mut commands: Commands) {
    for (entity, callback) in query.iter() {
        commands.run_system(callback.0);
        commands.entity(entity).remove::<Triggered>();
    }
}

examples/ecs/removal_detection.rs (line 48)

fn remove_component(
    time: Res<Time>,
    mut commands: Commands,
    query: Query<Entity, With<MyComponent>>,
) {
    // After two seconds have passed the `Component` is removed.
    if time.elapsed_seconds() > 2.0 {
        if let Some(entity) = query.iter().next() {
            commands.entity(entity).remove::<MyComponent>();
        }
    }
}

examples/ecs/component_hooks.rs (line 103)

fn trigger_hooks(
    mut commands: Commands,
    keys: Res<ButtonInput<KeyCode>>,
    index: Res<MyComponentIndex>,
) {
    for (key, entity) in index.iter() {
        if !keys.pressed(*key) {
            commands.entity(*entity).remove::<MyComponent>();
        }
    }
    for key in keys.get_just_pressed() {
        commands.spawn(MyComponent(*key));
    }
}

examples/audio/soundtrack.rs (line 124)

fn fade_in(
    mut commands: Commands,
    mut audio_sink: Query<(&mut AudioSink, Entity), With<FadeIn>>,
    time: Res<Time>,
) {
    for (audio, entity) in audio_sink.iter_mut() {
        audio.set_volume(audio.volume() + time.delta_seconds() / FADE_TIME);
        if audio.volume() >= 1.0 {
            audio.set_volume(1.0);
            commands.entity(entity).remove::<FadeIn>();
        }
    }
}

examples/asset/asset_decompression.rs (line 131)

fn decompress<A: Asset>(
    mut commands: Commands,
    asset_server: Res<AssetServer>,
    mut compressed_assets: ResMut<Assets<GzAsset>>,
    query: Query<(Entity, &Compressed<A>)>,
) {
    for (entity, Compressed { compressed, .. }) in query.iter() {
        let Some(GzAsset { uncompressed }) = compressed_assets.remove(compressed) else {
            continue;
        };

        let uncompressed = uncompressed.take::<A>().unwrap();

        commands
            .entity(entity)
            .remove::<Compressed<A>>()
            .insert(asset_server.add(uncompressed));
    }
}

examples/games/game_menu.rs (line 374)

    fn setting_button<T: Resource + Component + PartialEq + Copy>(
        interaction_query: Query<(&Interaction, &T, Entity), (Changed<Interaction>, With<Button>)>,
        mut selected_query: Query<(Entity, &mut UiImage), With<SelectedOption>>,
        mut commands: Commands,
        mut setting: ResMut<T>,
    ) {
        for (interaction, button_setting, entity) in &interaction_query {
            if *interaction == Interaction::Pressed && *setting != *button_setting {
                let (previous_button, mut previous_image) = selected_query.single_mut();
                previous_image.color = NORMAL_BUTTON;
                commands.entity(previous_button).remove::<SelectedOption>();
                commands.entity(entity).insert(SelectedOption);
                *setting = *button_setting;
            }
        }
    }

Additional examples can be found in:

• examples/3d/clearcoat.rs
• examples/3d/irradiance_volumes.rs
• examples/3d/shadow_caster_receiver.rs
• examples/3d/reflection_probes.rs
• examples/3d/anti_aliasing.rs
• examples/3d/ssao.rs
• examples/3d/deferred_rendering.rs
• examples/3d/bloom_3d.rs
• examples/2d/bloom_2d.rs
• examples/3d/transmission.rs

pub fn remove_by_id( &mut self, component_id: ComponentId ) -> &mut EntityCommands<'_>

Removes a component from the entity.

pub fn despawn(&mut self)

Despawns the entity.

See World::despawn for more details.

Note

This won’t clean up external references to the entity (such as parent-child relationships if you’re using bevy_hierarchy), which may leave the world in an invalid state.

Panics

The command will panic when applied if the associated entity does not exist.

Example

fn remove_character_system(
    mut commands: Commands,
    character_to_remove: Res<CharacterToRemove>
)
{
    commands.entity(character_to_remove.entity).despawn();
}

Examples found in repository

examples/games/alien_cake_addict.rs (line 199)

fn teardown(mut commands: Commands, entities: Query<Entity, (Without<Camera>, Without<Window>)>) {
    for entity in &entities {
        commands.entity(entity).despawn();
    }
}

examples/async_tasks/external_source_external_thread.rs (line 80)

fn move_text(
    mut commands: Commands,
    mut texts: Query<(Entity, &mut Transform), With<Text>>,
    time: Res<Time>,
) {
    for (entity, mut position) in &mut texts {
        position.translation -= Vec3::new(0.0, 100.0 * time.delta_seconds(), 0.0);
        if position.translation.y < -300.0 {
            commands.entity(entity).despawn();
        }
    }
}

examples/input/text_input.rs (line 138)

fn bubbling_text(
    mut commands: Commands,
    mut bubbles: Query<(Entity, &mut Transform, &mut Bubble)>,
    time: Res<Time>,
) {
    for (entity, mut transform, mut bubble) in bubbles.iter_mut() {
        if bubble.timer.tick(time.delta()).just_finished() {
            commands.entity(entity).despawn();
        }
        transform.translation.y += time.delta_seconds() * 100.0;
    }
}

examples/3d/pbr.rs (line 149)

fn environment_map_load_finish(
    mut commands: Commands,
    asset_server: Res<AssetServer>,
    environment_maps: Query<&EnvironmentMapLight>,
    label_query: Query<Entity, With<EnvironmentMapLabel>>,
) {
    if let Ok(environment_map) = environment_maps.get_single() {
        if asset_server.load_state(&environment_map.diffuse_map) == LoadState::Loaded
            && asset_server.load_state(&environment_map.specular_map) == LoadState::Loaded
        {
            if let Ok(label_entity) = label_query.get_single() {
                commands.entity(label_entity).despawn();
            }
        }
    }
}

examples/3d/tonemapping.rs (line 238)

fn drag_drop_image(
    image_mat: Query<&Handle<StandardMaterial>, With<HDRViewer>>,
    text: Query<Entity, (With<Text>, With<SceneNumber>)>,
    mut materials: ResMut<Assets<StandardMaterial>>,
    mut drop_events: EventReader<FileDragAndDrop>,
    asset_server: Res<AssetServer>,
    mut commands: Commands,
) {
    let Some(new_image) = drop_events.read().find_map(|e| match e {
        FileDragAndDrop::DroppedFile { path_buf, .. } => {
            Some(asset_server.load(path_buf.to_string_lossy().to_string()))
        }
        _ => None,
    }) else {
        return;
    };

    for mat_h in &image_mat {
        if let Some(mat) = materials.get_mut(mat_h) {
            mat.base_color_texture = Some(new_image.clone());

            // Despawn the image viewer instructions
            if let Ok(text_entity) = text.get_single() {
                commands.entity(text_entity).despawn();
            }
        }
    }
}

examples/3d/reflection_probes.rs (line 214)

fn change_reflection_type(
    mut commands: Commands,
    light_probe_query: Query<Entity, With<LightProbe>>,
    camera_query: Query<Entity, With<Camera3d>>,
    keyboard: Res<ButtonInput<KeyCode>>,
    mut app_status: ResMut<AppStatus>,
    cubemaps: Res<Cubemaps>,
) {
    // Only do anything if space was pressed.
    if !keyboard.just_pressed(KeyCode::Space) {
        return;
    }

    // Switch reflection mode.
    app_status.reflection_mode =
        ReflectionMode::try_from((app_status.reflection_mode as u32 + 1) % 3).unwrap();

    // Add or remove the light probe.
    for light_probe in light_probe_query.iter() {
        commands.entity(light_probe).despawn();
    }
    match app_status.reflection_mode {
        ReflectionMode::None | ReflectionMode::EnvironmentMap => {}
        ReflectionMode::ReflectionProbe => spawn_reflection_probe(&mut commands, &cubemaps),
    }

    // Add or remove the environment map from the camera.
    for camera in camera_query.iter() {
        match app_status.reflection_mode {
            ReflectionMode::None => {
                commands.entity(camera).remove::<EnvironmentMapLight>();
            }
            ReflectionMode::EnvironmentMap | ReflectionMode::ReflectionProbe => {
                commands
                    .entity(camera)
                    .insert(create_camera_environment_map_light(&cubemaps));
            }
        }
    }
}

Additional examples can be found in:

• examples/games/breakout.rs
• examples/ecs/component_hooks.rs

pub fn add<M>( &mut self, command: impl EntityCommand<M> ) -> &mut EntityCommands<'_>

where M: 'static,

Pushes an EntityCommand to the queue, which will get executed for the current Entity.

Examples

commands
    .spawn_empty()
    // Closures with this signature implement `EntityCommand`.
    .add(|entity: EntityWorldMut| {
        println!("Executed an EntityCommand for {:?}", entity.id());
    });

pub fn retain<T>(&mut self) -> &mut EntityCommands<'_>

where T: Bundle,

Removes all components except the given Bundle from the entity.

This can also be used to remove all the components from the entity by passing it an empty Bundle.

Example

#[derive(Component)]
struct Health(u32);
#[derive(Component)]
struct Strength(u32);
#[derive(Component)]
struct Defense(u32);

#[derive(Bundle)]
struct CombatBundle {
    health: Health,
    strength: Strength,
}

fn remove_combat_stats_system(mut commands: Commands, player: Res<PlayerEntity>) {
    commands
        .entity(player.entity)
        // You can retain a pre-defined Bundle of components,
        // with this removing only the Defense component
        .retain::<CombatBundle>()
        // You can also retain only a single component
        .retain::<Health>()
        // And you can remove all the components by passing in an empty Bundle
        .retain::<()>();
}

pub fn log_components(&mut self)

Logs the components of the entity at the info level.

Panics

The command will panic when applied if the associated entity does not exist.

pub fn commands(&mut self) -> Commands<'_, '_>

Returns the underlying Commands.

Trait Implementations

impl BuildChildren for EntityCommands<'_>

fn with_children( &mut self, spawn_children: impl FnOnce(&mut ChildBuilder<'_>) ) -> &mut EntityCommands<'_>

Takes a closure which builds children for this entity using ChildBuilder.

fn push_children(&mut self, children: &[Entity]) -> &mut EntityCommands<'_>

Pushes children to the back of the builder’s children. For any entities that are already a child of this one, this method does nothing.

fn insert_children( &mut self, index: usize, children: &[Entity] ) -> &mut EntityCommands<'_>

Inserts children at the given index.

fn remove_children(&mut self, children: &[Entity]) -> &mut EntityCommands<'_>

Removes the given children

fn add_child(&mut self, child: Entity) -> &mut EntityCommands<'_>

Adds a single child.

fn clear_children(&mut self) -> &mut EntityCommands<'_>

Removes all children from this entity. The Children component will be removed if it exists, otherwise this does nothing.

fn replace_children(&mut self, children: &[Entity]) -> &mut EntityCommands<'_>

Removes all current children from this entity, replacing them with the specified list of entities.

fn set_parent(&mut self, parent: Entity) -> &mut EntityCommands<'_>

Sets the parent of this entity.

fn remove_parent(&mut self) -> &mut EntityCommands<'_>

Removes the Parent of this entity.

impl BuildChildrenTransformExt for EntityCommands<'_>

fn set_parent_in_place(&mut self, parent: Entity) -> &mut EntityCommands<'_>

Change this entity’s parent while preserving this entity’s GlobalTransform by updating its Transform.

fn remove_parent_in_place(&mut self) -> &mut EntityCommands<'_>

Make this entity parentless while preserving this entity’s GlobalTransform by updating its Transform to be equal to its current GlobalTransform.

impl DespawnRecursiveExt for EntityCommands<'_>

fn despawn_recursive(self)

Despawns the provided entity and its children.

fn despawn_descendants(&mut self) -> &mut EntityCommands<'_>

Despawns all descendants of the given entity.

impl ReflectCommandExt for EntityCommands<'_>

fn insert_reflect( &mut self, component: Box<dyn Reflect> ) -> &mut EntityCommands<'_>

Adds the given boxed reflect component to the entity using the reflection data in AppTypeRegistry.

fn insert_reflect_with_registry<T>( &mut self, component: Box<dyn Reflect> ) -> &mut EntityCommands<'_>

where T: Resource + AsRef<TypeRegistry>,

Same as insert_reflect, but using the T resource as type registry instead of AppTypeRegistry.

fn remove_reflect( &mut self, component_type_path: impl Into<Cow<'static, str>> ) -> &mut EntityCommands<'_>

Removes from the entity the component with the given type name registered in AppTypeRegistry.

fn remove_reflect_with_registry<T>( &mut self, component_type_name: impl Into<Cow<'static, str>> ) -> &mut EntityCommands<'_>

where T: Resource + AsRef<TypeRegistry>,

Same as remove_reflect, but using the T resource as type registry instead of AppTypeRegistry.