Function vec3 

pub const fn vec3(x: f32, y: f32, z: f32) -> Vec3

Creates a 3-dimensional vector.

Examples found in repository

examples/3d/visibility_range.rs (line 15)

const CAMERA_FOCAL_POINT: Vec3 = vec3(0.0, 0.3, 0.0);

examples/3d/anisotropy.rs (line 14)

const CAMERA_INITIAL_POSITION: Vec3 = vec3(-0.4, 0.0, 0.0);

/// The current settings of the app, as chosen by the user.
#[derive(Resource)]
struct AppStatus {
    /// Which type of light is in the scene.
    light_mode: LightMode,
    /// Whether anisotropy is enabled.
    anisotropy_enabled: bool,
    /// Which mesh is visible
    visible_scene: Scene,
}

/// Which type of light we're using: a directional light, a point light, or an
/// environment map.
#[derive(Clone, Copy, PartialEq, Default)]
enum LightMode {
    /// A rotating directional light.
    #[default]
    Directional,
    /// A rotating point light.
    Point,
    /// An environment map (image-based lighting, including skybox).
    EnvironmentMap,
}

/// A component that stores the version of the material with anisotropy and the
/// version of the material without it.
///
/// This is placed on each mesh with a material. It exists so that the
/// appropriate system can replace the materials when the user presses Enter to
/// turn anisotropy on and off.
#[derive(Component)]
struct MaterialVariants {
    /// The version of the material in the glTF file, with anisotropy.
    anisotropic: Handle<StandardMaterial>,
    /// The version of the material with anisotropy removed.
    isotropic: Handle<StandardMaterial>,
}

#[derive(Default, Clone, Copy, PartialEq, Eq, Component)]
enum Scene {
    #[default]
    BarnLamp,
    Sphere,
}

impl Scene {
    fn next(&self) -> Self {
        match self {
            Self::BarnLamp => Self::Sphere,
            Self::Sphere => Self::BarnLamp,
        }
    }
}

impl Display for Scene {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let scene_name = match self {
            Self::BarnLamp => "Barn Lamp",
            Self::Sphere => "Sphere",
        };
        write!(f, "{scene_name}")
    }
}

/// The application entry point.
fn main() {
    App::new()
        .init_resource::<AppStatus>()
        .add_plugins(DefaultPlugins.set(WindowPlugin {
            primary_window: Some(Window {
                title: "Bevy Anisotropy Example".into(),
                ..default()
            }),
            ..default()
        }))
        .add_systems(Startup, setup)
        .add_systems(Update, create_material_variants)
        .add_systems(Update, animate_light)
        .add_systems(Update, rotate_camera)
        .add_systems(Update, (handle_input, update_help_text).chain())
        .run();
}

/// Creates the initial scene.
fn setup(mut commands: Commands, asset_server: Res<AssetServer>, app_status: Res<AppStatus>) {
    commands.spawn((
        Camera3d::default(),
        Transform::from_translation(CAMERA_INITIAL_POSITION).looking_at(Vec3::ZERO, Vec3::Y),
    ));

    spawn_directional_light(&mut commands);

    commands.spawn((
        SceneRoot(asset_server.load("models/AnisotropyBarnLamp/AnisotropyBarnLamp.gltf#Scene0")),
        Transform::from_xyz(0.0, 0.07, -0.13),
        Scene::BarnLamp,
    ));

    commands.spawn((
        Mesh3d(
            asset_server.add(
                Mesh::from(Sphere::new(0.1))
                    .with_generated_tangents()
                    .unwrap(),
            ),
        ),
        MeshMaterial3d(asset_server.add(StandardMaterial {
            base_color: palettes::tailwind::GRAY_300.into(),
            anisotropy_rotation: 0.5,
            anisotropy_strength: 1.,
            ..default()
        })),
        Scene::Sphere,
        Visibility::Hidden,
    ));

    spawn_text(&mut commands, &app_status);
}

/// Spawns the help text.
fn spawn_text(commands: &mut Commands, app_status: &AppStatus) {
    commands.spawn((
        app_status.create_help_text(),
        Node {
            position_type: PositionType::Absolute,
            bottom: px(12),
            left: px(12),
            ..default()
        },
    ));
}

/// For each material, creates a version with the anisotropy removed.
///
/// This allows the user to press Enter to toggle anisotropy on and off.
fn create_material_variants(
    mut commands: Commands,
    mut materials: ResMut<Assets<StandardMaterial>>,
    new_meshes: Query<
        (Entity, &MeshMaterial3d<StandardMaterial>),
        (
            Added<MeshMaterial3d<StandardMaterial>>,
            Without<MaterialVariants>,
        ),
    >,
) {
    for (entity, anisotropic_material_handle) in new_meshes.iter() {
        let Some(anisotropic_material) = materials.get(anisotropic_material_handle).cloned() else {
            continue;
        };

        commands.entity(entity).insert(MaterialVariants {
            anisotropic: anisotropic_material_handle.0.clone(),
            isotropic: materials.add(StandardMaterial {
                anisotropy_texture: None,
                anisotropy_strength: 0.0,
                anisotropy_rotation: 0.0,
                ..anisotropic_material
            }),
        });
    }
}

/// A system that animates the light every frame, if there is one.
fn animate_light(
    mut lights: Query<&mut Transform, Or<(With<DirectionalLight>, With<PointLight>)>>,
    time: Res<Time>,
) {
    let now = time.elapsed_secs();
    for mut transform in lights.iter_mut() {
        transform.translation = vec3(ops::cos(now), 1.0, ops::sin(now)) * vec3(3.0, 4.0, 3.0);
        transform.look_at(Vec3::ZERO, Vec3::Y);
    }
}

examples/3d/mixed_lighting.rs (line 115)

const INITIAL_SPHERE_POSITION: Vec3 = vec3(0.0, 0.5233223, 0.0);

fn main() {
    App::new()
        .add_plugins(DefaultPlugins.set(WindowPlugin {
            primary_window: Some(Window {
                title: "Bevy Mixed Lighting Example".into(),
                ..default()
            }),
            ..default()
        }))
        .add_plugins(MeshPickingPlugin)
        .insert_resource(AmbientLight {
            color: ClearColor::default().0,
            brightness: 10000.0,
            affects_lightmapped_meshes: true,
        })
        .init_resource::<AppStatus>()
        .add_message::<WidgetClickEvent<LightingMode>>()
        .add_message::<LightingModeChanged>()
        .add_systems(Startup, setup)
        .add_systems(Update, update_lightmaps)
        .add_systems(Update, update_directional_light)
        .add_systems(Update, make_sphere_nonpickable)
        .add_systems(Update, update_radio_buttons)
        .add_systems(Update, handle_lighting_mode_change)
        .add_systems(Update, widgets::handle_ui_interactions::<LightingMode>)
        .add_systems(Update, reset_sphere_position)
        .add_systems(Update, move_sphere)
        .add_systems(Update, adjust_help_text)
        .run();
}

/// Creates the scene.
fn setup(mut commands: Commands, asset_server: Res<AssetServer>, app_status: Res<AppStatus>) {
    spawn_camera(&mut commands);
    spawn_scene(&mut commands, &asset_server);
    spawn_buttons(&mut commands);
    spawn_help_text(&mut commands, &app_status);
}

/// Spawns the 3D camera.
fn spawn_camera(commands: &mut Commands) {
    commands
        .spawn(Camera3d::default())
        .insert(Transform::from_xyz(-0.7, 0.7, 1.0).looking_at(vec3(0.0, 0.3, 0.0), Vec3::Y));
}

/// Spawns the scene.
///
/// The scene is loaded from a glTF file.
fn spawn_scene(commands: &mut Commands, asset_server: &AssetServer) {
    commands
        .spawn(SceneRoot(
            asset_server.load(
                GltfAssetLabel::Scene(0)
                    .from_asset("models/MixedLightingExample/MixedLightingExample.gltf"),
            ),
        ))
        .observe(
            |_: On<SceneInstanceReady>,
             mut lighting_mode_changed_writer: MessageWriter<LightingModeChanged>| {
                // When the scene loads, send a `LightingModeChanged` event so
                // that we set up the lightmaps.
                lighting_mode_changed_writer.write(LightingModeChanged);
            },
        );
}

/// Spawns the buttons that allow the user to change the lighting mode.
fn spawn_buttons(commands: &mut Commands) {
    commands.spawn((
        widgets::main_ui_node(),
        children![widgets::option_buttons(
            "Lighting",
            &[
                (LightingMode::Baked, "Baked"),
                (LightingMode::MixedDirect, "Mixed (Direct)"),
                (LightingMode::MixedIndirect, "Mixed (Indirect)"),
                (LightingMode::RealTime, "Real-Time"),
            ],
        )],
    ));
}

/// Spawns the help text at the top of the window.
fn spawn_help_text(commands: &mut Commands, app_status: &AppStatus) {
    commands.spawn((
        create_help_text(app_status),
        Node {
            position_type: PositionType::Absolute,
            top: px(12),
            left: px(12),
            ..default()
        },
        HelpText,
    ));
}

/// Adds lightmaps to and/or removes lightmaps from objects in the scene when
/// the lighting mode changes.
///
/// This is also called right after the scene loads in order to set up the
/// lightmaps.
fn update_lightmaps(
    mut commands: Commands,
    asset_server: Res<AssetServer>,
    mut materials: ResMut<Assets<StandardMaterial>>,
    meshes: Query<(Entity, &GltfMeshName, &MeshMaterial3d<StandardMaterial>), With<Mesh3d>>,
    mut lighting_mode_changed_reader: MessageReader<LightingModeChanged>,
    app_status: Res<AppStatus>,
) {
    // Only run if the lighting mode changed. (Note that a change event is fired
    // when the scene first loads.)
    if lighting_mode_changed_reader.read().next().is_none() {
        return;
    }

    // Select the lightmap to use, based on the lighting mode.
    let lightmap: Option<Handle<Image>> = match app_status.lighting_mode {
        LightingMode::Baked => {
            Some(asset_server.load("lightmaps/MixedLightingExample-Baked.zstd.ktx2"))
        }
        LightingMode::MixedDirect => {
            Some(asset_server.load("lightmaps/MixedLightingExample-MixedDirect.zstd.ktx2"))
        }
        LightingMode::MixedIndirect => {
            Some(asset_server.load("lightmaps/MixedLightingExample-MixedIndirect.zstd.ktx2"))
        }
        LightingMode::RealTime => None,
    };

    'outer: for (entity, name, material) in &meshes {
        // Add lightmaps to or remove lightmaps from the scenery objects in the
        // scene (all objects but the sphere).
        //
        // Note that doing a linear search through the `LIGHTMAPS` array is
        // inefficient, but we do it anyway in this example to improve clarity.
        for (lightmap_name, uv_rect) in LIGHTMAPS {
            if &**name != lightmap_name {
                continue;
            }

            // Lightmap exposure defaults to zero, so we need to set it.
            if let Some(ref mut material) = materials.get_mut(material) {
                material.lightmap_exposure = LIGHTMAP_EXPOSURE;
            }

            // Add or remove the lightmap.
            match lightmap {
                Some(ref lightmap) => {
                    commands.entity(entity).insert(Lightmap {
                        image: (*lightmap).clone(),
                        uv_rect,
                        bicubic_sampling: false,
                    });
                }
                None => {
                    commands.entity(entity).remove::<Lightmap>();
                }
            }
            continue 'outer;
        }

        // Add lightmaps to or remove lightmaps from the sphere.
        if &**name == "Sphere" {
            // Lightmap exposure defaults to zero, so we need to set it.
            if let Some(ref mut material) = materials.get_mut(material) {
                material.lightmap_exposure = LIGHTMAP_EXPOSURE;
            }

            // Add or remove the lightmap from the sphere. We only apply the
            // lightmap in fully-baked mode.
            match (&lightmap, app_status.lighting_mode) {
                (Some(lightmap), LightingMode::Baked) => {
                    commands.entity(entity).insert(Lightmap {
                        image: (*lightmap).clone(),
                        uv_rect: SPHERE_UV_RECT,
                        bicubic_sampling: false,
                    });
                }
                _ => {
                    commands.entity(entity).remove::<Lightmap>();
                }
            }
        }
    }
}

/// Converts a uv rectangle from the OpenGL coordinate system (origin in the
/// lower left) to the Vulkan coordinate system (origin in the upper left) that
/// Bevy uses.
///
/// For this particular example, the baking tool happened to use the OpenGL
/// coordinate system, so it was more convenient to do the conversion at compile
/// time than to pre-calculate and hard-code the values.
const fn uv_rect_opengl(gl_min: Vec2, size: Vec2) -> Rect {
    let min = vec2(gl_min.x, 1.0 - gl_min.y - size.y);
    Rect {
        min,
        max: vec2(min.x + size.x, min.y + size.y),
    }
}

/// Ensures that clicking on the scene to move the sphere doesn't result in a
/// hit on the sphere itself.
fn make_sphere_nonpickable(
    mut commands: Commands,
    mut query: Query<(Entity, &Name), (With<Mesh3d>, Without<Pickable>)>,
) {
    for (sphere, name) in &mut query {
        if &**name == "Sphere" {
            commands.entity(sphere).insert(Pickable::IGNORE);
        }
    }
}

/// Updates the directional light settings as necessary when the lighting mode
/// changes.
fn update_directional_light(
    mut lights: Query<&mut DirectionalLight>,
    mut lighting_mode_changed_reader: MessageReader<LightingModeChanged>,
    app_status: Res<AppStatus>,
) {
    // Only run if the lighting mode changed. (Note that a change event is fired
    // when the scene first loads.)
    if lighting_mode_changed_reader.read().next().is_none() {
        return;
    }

    // Real-time direct light is used on the scenery if we're using mixed
    // indirect or real-time mode.
    let scenery_is_lit_in_real_time = matches!(
        app_status.lighting_mode,
        LightingMode::MixedIndirect | LightingMode::RealTime
    );

    for mut light in &mut lights {
        light.affects_lightmapped_mesh_diffuse = scenery_is_lit_in_real_time;
        // Don't bother enabling shadows if they won't show up on the scenery.
        light.shadows_enabled = scenery_is_lit_in_real_time;
    }
}

/// Updates the state of the selection widgets at the bottom of the window when
/// the lighting mode changes.
fn update_radio_buttons(
    mut widgets: Query<
        (
            Entity,
            Option<&mut BackgroundColor>,
            Has<Text>,
            &WidgetClickSender<LightingMode>,
        ),
        Or<(With<RadioButton>, With<RadioButtonText>)>,
    >,
    app_status: Res<AppStatus>,
    mut writer: TextUiWriter,
) {
    for (entity, image, has_text, sender) in &mut widgets {
        let selected = **sender == app_status.lighting_mode;

        if let Some(mut bg_color) = image {
            widgets::update_ui_radio_button(&mut bg_color, selected);
        }
        if has_text {
            widgets::update_ui_radio_button_text(entity, &mut writer, selected);
        }
    }
}

/// Handles clicks on the widgets at the bottom of the screen and fires
/// [`LightingModeChanged`] events.
fn handle_lighting_mode_change(
    mut widget_click_event_reader: MessageReader<WidgetClickEvent<LightingMode>>,
    mut lighting_mode_changed_writer: MessageWriter<LightingModeChanged>,
    mut app_status: ResMut<AppStatus>,
) {
    for event in widget_click_event_reader.read() {
        app_status.lighting_mode = **event;
        lighting_mode_changed_writer.write(LightingModeChanged);
    }
}

/// Moves the sphere to its original position when the user selects the baked
/// lighting mode.
///
/// As the light from the sphere is precomputed and depends on the sphere's
/// original position, the sphere must be placed there in order for the lighting
/// to be correct.
fn reset_sphere_position(
    mut objects: Query<(&Name, &mut Transform)>,
    mut lighting_mode_changed_reader: MessageReader<LightingModeChanged>,
    app_status: Res<AppStatus>,
) {
    // Only run if the lighting mode changed and if the lighting mode is
    // `LightingMode::Baked`. (Note that a change event is fired when the scene
    // first loads.)
    if lighting_mode_changed_reader.read().next().is_none()
        || app_status.lighting_mode != LightingMode::Baked
    {
        return;
    }

    for (name, mut transform) in &mut objects {
        if &**name == "Sphere" {
            transform.translation = INITIAL_SPHERE_POSITION;
            break;
        }
    }
}

/// Updates the position of the sphere when the user clicks on a spot in the
/// scene.
///
/// Note that the position of the sphere is locked in baked lighting mode.
fn move_sphere(
    mouse_button_input: Res<ButtonInput<MouseButton>>,
    pointers: Query<&PointerInteraction>,
    mut meshes: Query<(&GltfMeshName, &ChildOf), With<Mesh3d>>,
    mut transforms: Query<&mut Transform>,
    app_status: Res<AppStatus>,
) {
    // Only run when the left button is clicked and we're not in baked lighting
    // mode.
    if app_status.lighting_mode == LightingMode::Baked
        || !mouse_button_input.pressed(MouseButton::Left)
    {
        return;
    }

    // Find the sphere.
    let Some(child_of) = meshes
        .iter_mut()
        .filter_map(|(name, child_of)| {
            if &**name == "Sphere" {
                Some(child_of)
            } else {
                None
            }
        })
        .next()
    else {
        return;
    };

    // Grab its transform.
    let Ok(mut transform) = transforms.get_mut(child_of.parent()) else {
        return;
    };

    // Set its transform to the appropriate position, as determined by the
    // picking subsystem.
    for interaction in pointers.iter() {
        if let Some(&(
            _,
            HitData {
                position: Some(position),
                ..
            },
        )) = interaction.get_nearest_hit()
        {
            transform.translation = position + vec3(0.0, SPHERE_OFFSET, 0.0);
        }
    }
}

examples/stress_tests/many_cubes.rs (line 505)

fn fast_hue_to_rgb(hue: f32) -> Vec3 {
    (hue * 6.0 - vec3(3.0, 2.0, 4.0)).abs() * vec3(1.0, -1.0, -1.0) + vec3(-1.0, 2.0, 2.0)
}

examples/shader_advanced/custom_phase_item.rs (line 158)

static VERTICES: [Vertex; 3] = [
    Vertex::new(vec3(-0.866, -0.5, 0.5), vec3(1.0, 0.0, 0.0)),
    Vertex::new(vec3(0.866, -0.5, 0.5), vec3(0.0, 1.0, 0.0)),
    Vertex::new(vec3(0.0, 1.0, 0.5), vec3(0.0, 0.0, 1.0)),
];

examples/shader_advanced/render_depth_to_texture.rs (line 251)

fn spawn_main_camera(commands: &mut Commands) {
    commands.spawn((
        Camera3d::default(),
        Transform::from_xyz(5.0, 2.0, 30.0).looking_at(vec3(5.0, 2.0, 0.0), Vec3::Y),
        // Disable antialiasing just for simplicity's sake.
        Msaa::Off,
    ));
}

/// Spawns the instructional text at the top of the screen.
fn spawn_instructions(commands: &mut Commands) {
    commands.spawn((
        Text::new("Use WASD to move the secondary camera"),
        Node {
            position_type: PositionType::Absolute,
            top: Val::Px(12.0),
            left: Val::Px(12.0),
            ..Node::default()
        },
    ));
}

/// Spins the cube a bit every frame.
fn rotate_cube(mut cubes: Query<&mut Transform, With<RotatingCube>>, time: Res<Time>) {
    for mut transform in &mut cubes {
        transform.rotate_x(1.5 * time.delta_secs());
        transform.rotate_y(1.1 * time.delta_secs());
        transform.rotate_z(-1.3 * time.delta_secs());
    }
}

impl Material for ShowDepthTextureMaterial {
    fn fragment_shader() -> ShaderRef {
        SHADER_ASSET_PATH.into()
    }
}

impl ViewNode for CopyDepthTextureNode {
    type ViewQuery = (Read<ExtractedCamera>, Read<ViewDepthTexture>);

    fn run<'w>(
        &self,
        _: &mut RenderGraphContext,
        render_context: &mut RenderContext<'w>,
        (camera, depth_texture): QueryItem<'w, '_, Self::ViewQuery>,
        world: &'w World,
    ) -> Result<(), NodeRunError> {
        // Make sure we only run on the depth-only camera.
        // We could make a marker component for that camera and extract it to
        // the render world, but using `order` as a tag to tell the main camera
        // and the depth-only camera apart works in a pinch.
        if camera.order >= 0 {
            return Ok(());
        }

        // Grab the texture we're going to copy to.
        let demo_depth_texture = world.resource::<DemoDepthTexture>();
        let image_assets = world.resource::<RenderAssets<GpuImage>>();
        let Some(demo_depth_image) = image_assets.get(demo_depth_texture.0.id()) else {
            return Ok(());
        };

        // Perform the copy.
        render_context.add_command_buffer_generation_task(move |render_device| {
            let mut command_encoder =
                render_device.create_command_encoder(&CommandEncoderDescriptor {
                    label: Some("copy depth to demo texture command encoder"),
                });
            command_encoder.push_debug_group("copy depth to demo texture");

            // Copy from the view's depth texture to the destination depth
            // texture.
            command_encoder.copy_texture_to_texture(
                TexelCopyTextureInfo {
                    texture: &depth_texture.texture,
                    mip_level: 0,
                    origin: Origin3d::default(),
                    aspect: TextureAspect::DepthOnly,
                },
                TexelCopyTextureInfo {
                    texture: &demo_depth_image.texture,
                    mip_level: 0,
                    origin: Origin3d::default(),
                    aspect: TextureAspect::DepthOnly,
                },
                Extent3d {
                    width: DEPTH_TEXTURE_SIZE,
                    height: DEPTH_TEXTURE_SIZE,
                    depth_or_array_layers: 1,
                },
            );

            command_encoder.pop_debug_group();
            command_encoder.finish()
        });

        Ok(())
    }
}

impl FromWorld for DemoDepthTexture {
    fn from_world(world: &mut World) -> Self {
        let mut images = world.resource_mut::<Assets<Image>>();

        // Create a new 32-bit floating point depth texture.
        let mut depth_image = Image::new_uninit(
            Extent3d {
                width: DEPTH_TEXTURE_SIZE,
                height: DEPTH_TEXTURE_SIZE,
                depth_or_array_layers: 1,
            },
            TextureDimension::D2,
            TextureFormat::Depth32Float,
            RenderAssetUsages::default(),
        );

        // Create a sampler. Note that this needs to specify a `compare`
        // function in order to be compatible with depth textures.
        depth_image.sampler = ImageSampler::Descriptor(ImageSamplerDescriptor {
            label: Some("custom depth image sampler".to_owned()),
            compare: Some(ImageCompareFunction::Always),
            ..ImageSamplerDescriptor::default()
        });

        let depth_image_handle = images.add(depth_image);
        DemoDepthTexture(depth_image_handle)
    }
}

impl ExtractResource for DemoDepthTexture {
    type Source = Self;

    fn extract_resource(source: &Self::Source) -> Self {
        // Share the `DemoDepthTexture` resource over to the render world so
        // that our `CopyDepthTextureNode` can access it.
        (*source).clone()
    }
}

/// Draws an outline of the depth texture on the screen.
fn draw_camera_gizmo(cameras: Query<(&Camera, &GlobalTransform)>, mut gizmos: Gizmos) {
    for (camera, transform) in &cameras {
        // As above, we use the order as a cheap tag to tell the depth texture
        // apart from the main texture.
        if camera.order >= 0 {
            continue;
        }

        // Draw a cone representing the camera.
        gizmos.primitive_3d(
            &Cone {
                radius: 1.0,
                height: 3.0,
            },
            Isometry3d::new(
                transform.translation(),
                // We have to rotate here because `Cone` primitives are oriented
                // along +Y and cameras point along +Z.
                transform.rotation() * Quat::from_rotation_x(FRAC_PI_2),
            ),
            LIME,
        );
    }
}

/// Orbits the cube when WASD is pressed.
fn move_camera(
    mut cameras: Query<(&Camera, &mut Transform)>,
    keyboard: Res<ButtonInput<KeyCode>>,
    time: Res<Time>,
) {
    for (camera, mut transform) in &mut cameras {
        // Only affect the depth camera.
        if camera.order >= 0 {
            continue;
        }

        // Convert the camera's position from Cartesian to spherical coordinates.
        let mut spherical_coords = SphericalCoordinates::from_cartesian(transform.translation);

        // Modify those spherical coordinates as appropriate.
        let mut changed = false;
        if keyboard.pressed(KeyCode::KeyW) {
            spherical_coords.inclination -= time.delta_secs() * CAMERA_MOVEMENT_SPEED;
            changed = true;
        }
        if keyboard.pressed(KeyCode::KeyS) {
            spherical_coords.inclination += time.delta_secs() * CAMERA_MOVEMENT_SPEED;
            changed = true;
        }
        if keyboard.pressed(KeyCode::KeyA) {
            spherical_coords.azimuth += time.delta_secs() * CAMERA_MOVEMENT_SPEED;
            changed = true;
        }
        if keyboard.pressed(KeyCode::KeyD) {
            spherical_coords.azimuth -= time.delta_secs() * CAMERA_MOVEMENT_SPEED;
            changed = true;
        }

        // If they were changed, convert from spherical coordinates back to
        // Cartesian ones, and update the camera's transform.
        if changed {
            spherical_coords.inclination = spherical_coords.inclination.clamp(0.01, PI - 0.01);
            transform.translation = spherical_coords.to_cartesian();
            transform.look_at(Vec3::ZERO, Vec3::Y);
        }
    }
}

impl SphericalCoordinates {
    /// [Converts] from Cartesian coordinates to spherical coordinates.
    ///
    /// [Converts]: https://en.wikipedia.org/wiki/Spherical_coordinate_system#Cartesian_coordinates
    fn from_cartesian(p: Vec3) -> SphericalCoordinates {
        let radius = p.length();
        SphericalCoordinates {
            radius,
            inclination: acos(p.y / radius),
            azimuth: atan2(p.z, p.x),
        }
    }

    /// [Converts] from spherical coordinates to Cartesian coordinates.
    ///
    /// [Converts]: https://en.wikipedia.org/wiki/Spherical_coordinate_system#Cartesian_coordinates
    fn to_cartesian(self) -> Vec3 {
        let (sin_inclination, cos_inclination) = sin_cos(self.inclination);
        let (sin_azimuth, cos_azimuth) = sin_cos(self.azimuth);
        self.radius
            * vec3(
                sin_inclination * cos_azimuth,
                cos_inclination,
                sin_inclination * sin_azimuth,
            )
    }

Additional examples can be found in:

• examples/3d/clearcoat.rs
• examples/3d/clustered_decals.rs
• examples/3d/pcss.rs
• examples/3d/irradiance_volumes.rs
• examples/3d/ssr.rs
• examples/3d/fog_volumes.rs
• examples/3d/mesh_ray_cast.rs
• examples/movement/smooth_follow.rs
• examples/shader_advanced/specialized_mesh_pipeline.rs
• examples/animation/eased_motion.rs
• examples/3d/light_textures.rs
• examples/3d/volumetric_fog.rs