use std::f32::consts::PI;  use bevy::{     color::palettes::basic::{BLUE, LIME, RED},     light::{CascadeShadowConfigBuilder, NotShadowCaster, NotShadowReceiver},     prelude::*, };  fn main() {     println!(         "Controls:     C      - toggle shadow casters (i.e. casters become not, and not casters become casters)     R      - toggle shadow receivers (i.e. receivers become not, and not receivers become receivers)     L      - switch between directional and point lights"     );     App::new()         .add_plugins(DefaultPlugins)         .add_systems(Startup, setup)         .add_systems(Update, (toggle_light, toggle_shadows))         .run(); }  /// set up a 3D scene to test shadow biases and perspective projections fn setup(     mut commands: Commands,     mut meshes: ResMut<Assets<Mesh>>,     mut materials: ResMut<Assets<StandardMaterial>>, ) {     let spawn_plane_depth = 500.0f32;     let spawn_height = 2.0;     let sphere_radius = 0.25;      let white_handle = materials.add(StandardMaterial {         base_color: Color::WHITE,         perceptual_roughness: 1.0,         ..default()     });     let sphere_handle = meshes.add(Sphere::new(sphere_radius));      // sphere - initially a caster     commands.spawn((         Mesh3d(sphere_handle.clone()),         MeshMaterial3d(materials.add(Color::from(RED))),         Transform::from_xyz(-1.0, spawn_height, 0.0),     ));      // sphere - initially not a caster     commands.spawn((         Mesh3d(sphere_handle),         MeshMaterial3d(materials.add(Color::from(BLUE))),         Transform::from_xyz(1.0, spawn_height, 0.0),         NotShadowCaster,     ));      // floating plane - initially not a shadow receiver and not a caster     commands.spawn((         Mesh3d(meshes.add(Plane3d::default().mesh().size(20.0, 20.0))),         MeshMaterial3d(materials.add(Color::from(LIME))),         Transform::from_xyz(0.0, 1.0, -10.0),         NotShadowCaster,         NotShadowReceiver,     ));      // lower ground plane - initially a shadow receiver     commands.spawn((         Mesh3d(meshes.add(Plane3d::default().mesh().size(20.0, 20.0))),         MeshMaterial3d(white_handle),     ));      println!("Using DirectionalLight");      commands.spawn((         PointLight {             intensity: 0.0,             range: spawn_plane_depth,             color: Color::WHITE,             shadows_enabled: true,             ..default()         },         Transform::from_xyz(5.0, 5.0, 0.0),     ));      commands.spawn((         DirectionalLight {             illuminance: light_consts::lux::OVERCAST_DAY,             shadows_enabled: true,             ..default()         },         Transform::from_rotation(Quat::from_euler(EulerRot::ZYX, 0.0, PI / 2., -PI / 4.)),         CascadeShadowConfigBuilder {             first_cascade_far_bound: 7.0,             maximum_distance: 25.0,             ..default()         }         .build(),     ));      // camera     commands.spawn((         Camera3d::default(),         Transform::from_xyz(-5.0, 5.0, 5.0).looking_at(Vec3::new(-1.0, 1.0, 0.0), Vec3::Y),     )); }  fn toggle_light(     input: Res<ButtonInput<KeyCode>>,     mut point_lights: Query<&mut PointLight>,     mut directional_lights: Query<&mut DirectionalLight>, ) {     if input.just_pressed(KeyCode::KeyL) {         for mut light in &mut point_lights {             light.intensity = if light.intensity == 0.0 {                 println!("Using PointLight");                 1_000_000.0 // Mini-sun point light             } else {                 0.0             };         }         for mut light in &mut directional_lights {             light.illuminance = if light.illuminance == 0.0 {                 println!("Using DirectionalLight");                 light_consts::lux::OVERCAST_DAY             } else {                 0.0             };         }     } }  fn toggle_shadows(     mut commands: Commands,     input: Res<ButtonInput<KeyCode>>,     mut queries: ParamSet<(         Query<Entity, (With<Mesh3d>, With<NotShadowCaster>)>,         Query<Entity, (With<Mesh3d>, With<NotShadowReceiver>)>,         Query<Entity, (With<Mesh3d>, Without<NotShadowCaster>)>,         Query<Entity, (With<Mesh3d>, Without<NotShadowReceiver>)>,     )>, ) {     if input.just_pressed(KeyCode::KeyC) {         println!("Toggling casters");         for entity in queries.p0().iter() {             commands.entity(entity).remove::<NotShadowCaster>();         }         for entity in queries.p2().iter() {             commands.entity(entity).insert(NotShadowCaster);         }     }     if input.just_pressed(KeyCode::KeyR) {         println!("Toggling receivers");         for entity in queries.p1().iter() {             commands.entity(entity).remove::<NotShadowReceiver>();         }         for entity in queries.p3().iter() {             commands.entity(entity).insert(NotShadowReceiver);         }     } }