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examples: Add many_lights example for testing many point lights
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‎Cargo.toml

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@@ -191,6 +191,10 @@ path = "examples/3d/manual_gltf_animation_player.rs"
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name = "many_cubes"
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path = "examples/3d/many_cubes.rs"
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[[example]]
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name = "many_lights"
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path = "examples/3d/many_lights.rs"
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[[example]]
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name = "msaa"
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path = "examples/3d/msaa.rs"

‎examples/3d/many_lights.rs

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use bevy::{
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diagnostic::{FrameTimeDiagnosticsPlugin, LogDiagnosticsPlugin},
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math::{DVec2, DVec3},
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pbr::{ExtractedPointLight, GlobalLightMeta},
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prelude::*,
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render::{RenderApp, RenderStage},
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};
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fn main() {
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App::new()
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.insert_resource(WindowDescriptor {
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width: 1024.0,
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height: 768.0,
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title: "many_lights".to_string(),
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present_mode: bevy::window::PresentMode::Immediate,
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..default()
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})
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.add_plugins(DefaultPlugins)
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.add_plugin(FrameTimeDiagnosticsPlugin::default())
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.add_plugin(LogDiagnosticsPlugin::default())
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.add_startup_system(setup)
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.add_system(move_camera)
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.add_system(print_light_count)
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.add_plugin(LogVisibleLights)
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.run();
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}
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fn setup(
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mut commands: Commands,
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mut meshes: ResMut<Assets<Mesh>>,
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mut materials: ResMut<Assets<StandardMaterial>>,
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) {
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const LIGHT_RADIUS: f32 = 0.3;
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const LIGHT_INTENSITY: f32 = 5.0;
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const RADIUS: f32 = 50.0;
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const N_LIGHTS: usize = 100_000;
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commands.spawn_bundle(PbrBundle {
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mesh: meshes.add(Mesh::from(shape::Icosphere {
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radius: RADIUS,
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subdivisions: 9,
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})),
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material: materials.add(StandardMaterial::from(Color::WHITE)),
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transform: Transform::from_scale(Vec3::splat(-1.0)),
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..default()
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});
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let mesh = meshes.add(Mesh::from(shape::Cube { size: 1.0 }));
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let material = materials.add(StandardMaterial {
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base_color: Color::PINK,
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..default()
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});
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// NOTE: This pattern is good for testing performance of culling as it provides roughly
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// the same number of visible meshes regardless of the viewing angle.
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// NOTE: f64 is used to avoid precision issues that produce visual artifacts in the distribution
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let golden_ratio = 0.5f64 * (1.0f64 + 5.0f64.sqrt());
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for i in 0..N_LIGHTS {
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let spherical_polar_theta_phi = fibonacci_spiral_on_sphere(golden_ratio, i, N_LIGHTS);
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let unit_sphere_p = spherical_polar_to_cartesian(spherical_polar_theta_phi);
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commands.spawn_bundle(PointLightBundle {
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point_light: PointLight {
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range: LIGHT_RADIUS,
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intensity: LIGHT_INTENSITY,
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..default()
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},
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transform: Transform::from_translation((RADIUS as f64 * unit_sphere_p).as_vec3()),
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..default()
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});
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}
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// camera
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commands.spawn_bundle(PerspectiveCameraBundle::default());
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// add one cube, the only one with strong handles
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// also serves as a reference point during rotation
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commands.spawn_bundle(PbrBundle {
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mesh,
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material,
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transform: Transform {
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translation: Vec3::new(0.0, RADIUS as f32, 0.0),
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scale: Vec3::splat(5.0),
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..default()
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},
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..default()
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});
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}
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// NOTE: This epsilon value is apparently optimal for optimizing for the average
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// nearest-neighbor distance. See:
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// http://extremelearning.com.au/how-to-evenly-distribute-points-on-a-sphere-more-effectively-than-the-canonical-fibonacci-lattice/
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// for details.
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const EPSILON: f64 = 0.36;
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fn fibonacci_spiral_on_sphere(golden_ratio: f64, i: usize, n: usize) -> DVec2 {
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DVec2::new(
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2.0 * std::f64::consts::PI * (i as f64 / golden_ratio),
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(1.0 - 2.0 * (i as f64 + EPSILON) / (n as f64 - 1.0 + 2.0 * EPSILON)).acos(),
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)
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}
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fn spherical_polar_to_cartesian(p: DVec2) -> DVec3 {
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let (sin_theta, cos_theta) = p.x.sin_cos();
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let (sin_phi, cos_phi) = p.y.sin_cos();
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DVec3::new(cos_theta * sin_phi, sin_theta * sin_phi, cos_phi)
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}
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// System for rotating the camera
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fn move_camera(time: Res<Time>, mut camera_query: Query<&mut Transform, With<Camera>>) {
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let mut camera_transform = camera_query.single_mut();
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camera_transform.rotate(Quat::from_rotation_z(time.delta_seconds() * 0.15));
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camera_transform.rotate(Quat::from_rotation_x(time.delta_seconds() * 0.15));
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}
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// System for printing the number of meshes on every tick of the timer
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fn print_light_count(time: Res<Time>, mut timer: Local<PrintingTimer>, lights: Query<&PointLight>) {
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timer.0.tick(time.delta());
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if timer.0.just_finished() {
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info!("Lights: {}", lights.iter().len(),);
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}
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}
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struct LogVisibleLights;
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impl Plugin for LogVisibleLights {
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fn build(&self, app: &mut App) {
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let render_app = match app.get_sub_app_mut(RenderApp) {
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Ok(render_app) => render_app,
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Err(_) => return,
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};
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render_app
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.add_system_to_stage(RenderStage::Extract, extract_time)
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.add_system_to_stage(RenderStage::Prepare, print_visible_light_count);
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}
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}
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// System for printing the number of meshes on every tick of the timer
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fn print_visible_light_count(
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time: Res<Time>,
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mut timer: Local<PrintingTimer>,
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visible: Query<&ExtractedPointLight>,
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global_light_meta: Res<GlobalLightMeta>,
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) {
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timer.0.tick(time.delta());
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if timer.0.just_finished() {
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info!(
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"Visible Lights: {}, Rendered Lights: {}",
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visible.iter().len(),
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global_light_meta.entity_to_index.len()
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);
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}
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}
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fn extract_time(mut commands: Commands, time: Res<Time>) {
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commands.insert_resource(time.into_inner().clone());
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}
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struct PrintingTimer(Timer);
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impl Default for PrintingTimer {
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fn default() -> Self {
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Self(Timer::from_seconds(1.0, true))
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}
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}

‎examples/README.md

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@@ -106,6 +106,7 @@ Example | File | Description
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`load_gltf` | [`3d/load_gltf.rs`](./3d/load_gltf.rs) | Loads and renders a gltf file as a scene
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`manual_gltf_animation_player` | [`3d/manual_gltf_animation_player.rs`](./3d/manual_gltf_animation_player.rs) | Loads and manually renders a gltf file with animations
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`many_cubes` | [`3d/many_cubes.rs`](./3d/many_cubes.rs) | Simple benchmark to test per-entity draw overhead
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`many_lights` | [`3d/many_lights.rs`](./3d/many_lights.rs) | Simple benchmark to test rendering many point lights
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`msaa` | [`3d/msaa.rs`](./3d/msaa.rs) | Configures MSAA (Multi-Sample Anti-Aliasing) for smoother edges
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`orthographic` | [`3d/orthographic.rs`](./3d/orthographic.rs) | Shows how to create a 3D orthographic view (for isometric-look games or CAD applications)
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`parenting` | [`3d/parenting.rs`](./3d/parenting.rs) | Demonstrates parent->child relationships and relative transformations

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