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many_cubes.rs
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many_cubes.rs
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//! Simple benchmark to test per-entity draw overhead.
//!
//! To measure performance realistically, be sure to run this in release mode.
//! `cargo run --example many_cubes --release`
//!
//! By default, this arranges the meshes in a cubical pattern, where the number of visible meshes
//! varies with the viewing angle. You can choose to run the demo with a spherical pattern that
//! distributes the meshes evenly.
//!
//! To start the demo using the spherical layout run
//! `cargo run --example many_cubes --release sphere`
use std::f64::consts::PI;
use bevy::{
diagnostic::{FrameTimeDiagnosticsPlugin, LogDiagnosticsPlugin},
math::{DVec2, DVec3},
prelude::*,
window::{PresentMode, WindowPlugin},
};
fn main() {
App::new()
.add_plugins(DefaultPlugins.set(WindowPlugin {
primary_window: Some(Window {
present_mode: PresentMode::AutoNoVsync,
..default()
}),
..default()
}))
.add_plugin(FrameTimeDiagnosticsPlugin::default())
.add_plugin(LogDiagnosticsPlugin::default())
.add_startup_system(setup)
.add_system(move_camera)
.add_system(print_mesh_count)
.run();
}
fn setup(
mut commands: Commands,
mut meshes: ResMut<Assets<Mesh>>,
mut materials: ResMut<Assets<StandardMaterial>>,
) {
warn!(include_str!("warning_string.txt"));
const WIDTH: usize = 200;
const HEIGHT: usize = 200;
let mesh = meshes.add(Mesh::from(shape::Cube { size: 1.0 }));
let material = materials.add(StandardMaterial {
base_color: Color::PINK,
..default()
});
match std::env::args().nth(1).as_deref() {
Some("sphere") => {
// NOTE: This pattern is good for testing performance of culling as it provides roughly
// the same number of visible meshes regardless of the viewing angle.
const N_POINTS: usize = WIDTH * HEIGHT * 4;
// NOTE: f64 is used to avoid precision issues that produce visual artifacts in the distribution
let radius = WIDTH as f64 * 2.5;
let golden_ratio = 0.5f64 * (1.0f64 + 5.0f64.sqrt());
for i in 0..N_POINTS {
let spherical_polar_theta_phi =
fibonacci_spiral_on_sphere(golden_ratio, i, N_POINTS);
let unit_sphere_p = spherical_polar_to_cartesian(spherical_polar_theta_phi);
commands.spawn(PbrBundle {
mesh: mesh.clone_weak(),
material: material.clone_weak(),
transform: Transform::from_translation((radius * unit_sphere_p).as_vec3()),
..default()
});
}
// camera
commands.spawn(Camera3dBundle::default());
}
_ => {
// NOTE: This pattern is good for demonstrating that frustum culling is working correctly
// as the number of visible meshes rises and falls depending on the viewing angle.
for x in 0..WIDTH {
for y in 0..HEIGHT {
// introduce spaces to break any kind of moiré pattern
if x % 10 == 0 || y % 10 == 0 {
continue;
}
// cube
commands.spawn(PbrBundle {
mesh: mesh.clone_weak(),
material: material.clone_weak(),
transform: Transform::from_xyz((x as f32) * 2.5, (y as f32) * 2.5, 0.0),
..default()
});
commands.spawn(PbrBundle {
mesh: mesh.clone_weak(),
material: material.clone_weak(),
transform: Transform::from_xyz(
(x as f32) * 2.5,
HEIGHT as f32 * 2.5,
(y as f32) * 2.5,
),
..default()
});
commands.spawn(PbrBundle {
mesh: mesh.clone_weak(),
material: material.clone_weak(),
transform: Transform::from_xyz((x as f32) * 2.5, 0.0, (y as f32) * 2.5),
..default()
});
commands.spawn(PbrBundle {
mesh: mesh.clone_weak(),
material: material.clone_weak(),
transform: Transform::from_xyz(0.0, (x as f32) * 2.5, (y as f32) * 2.5),
..default()
});
}
}
// camera
commands.spawn(Camera3dBundle {
transform: Transform::from_xyz(WIDTH as f32, HEIGHT as f32, WIDTH as f32),
..default()
});
}
}
// add one cube, the only one with strong handles
// also serves as a reference point during rotation
commands.spawn(PbrBundle {
mesh,
material,
transform: Transform {
translation: Vec3::new(0.0, HEIGHT as f32 * 2.5, 0.0),
scale: Vec3::splat(5.0),
..default()
},
..default()
});
commands.spawn(DirectionalLightBundle { ..default() });
}
// NOTE: This epsilon value is apparently optimal for optimizing for the average
// nearest-neighbor distance. See:
// http://extremelearning.com.au/how-to-evenly-distribute-points-on-a-sphere-more-effectively-than-the-canonical-fibonacci-lattice/
// for details.
const EPSILON: f64 = 0.36;
fn fibonacci_spiral_on_sphere(golden_ratio: f64, i: usize, n: usize) -> DVec2 {
DVec2::new(
PI * 2. * (i as f64 / golden_ratio),
(1.0 - 2.0 * (i as f64 + EPSILON) / (n as f64 - 1.0 + 2.0 * EPSILON)).acos(),
)
}
fn spherical_polar_to_cartesian(p: DVec2) -> DVec3 {
let (sin_theta, cos_theta) = p.x.sin_cos();
let (sin_phi, cos_phi) = p.y.sin_cos();
DVec3::new(cos_theta * sin_phi, sin_theta * sin_phi, cos_phi)
}
// System for rotating the camera
fn move_camera(time: Res<Time>, mut camera_query: Query<&mut Transform, With<Camera>>) {
let mut camera_transform = camera_query.single_mut();
let delta = time.delta_seconds() * 0.15;
camera_transform.rotate_z(delta);
camera_transform.rotate_x(delta);
}
// System for printing the number of meshes on every tick of the timer
fn print_mesh_count(
time: Res<Time>,
mut timer: Local<PrintingTimer>,
sprites: Query<(&Handle<Mesh>, &ComputedVisibility)>,
) {
timer.tick(time.delta());
if timer.just_finished() {
info!(
"Meshes: {} - Visible Meshes {}",
sprites.iter().len(),
sprites.iter().filter(|(_, cv)| cv.is_visible()).count(),
);
}
}
#[derive(Deref, DerefMut)]
struct PrintingTimer(Timer);
impl Default for PrintingTimer {
fn default() -> Self {
Self(Timer::from_seconds(1.0, TimerMode::Repeating))
}
}