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Use proton scale for small scale example

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Aevyrie 2024-12-23 22:56:03 -08:00
parent 1b56ac9e63
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1 changed files with 25 additions and 18 deletions
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43
examples/small_scale.rs
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@ -3,15 +3,15 @@
//! being mixed in games that use double precision (f64) worlds, but you can use this floating
//! origin plugin to work on almost any set of scales.
//!
//! In this example, we will be spawning spheres the size of carbon atoms, across the width of the
//! In this example, we will be spawning spheres the size of protons, across the width of the
//! milky way galaxy.
use bevy::prelude::*;
use bevy_math::DVec3;
use big_space::prelude::*;
const BIG_DISTANCE: f64 = 100_000_000_000_000_000_000.0; // Diameter of the milky way galaxy
const SMALL_SCALE: f32 = 0.000_000_000_154; // Diameter of a carbon atom
const UNIVERSE_DIA: f64 = 8.8e26; // Diameter of the observable universe
const PROTON_DIA: f32 = 1.68e-15; // Diameter of a proton
fn main() {
App::new()
@ -28,7 +28,7 @@ fn main() {
}
#[derive(Component)]
struct Atom;
struct Proton;
fn setup_scene(
mut commands: Commands,
@ -39,40 +39,40 @@ fn setup_scene(
// Because we are working on such small scales, we need to make the grid very small. This
// ensures that the maximum floating point error is also very small, because no entities can
// ever get farther than `SMALL_SCALE * 500` units from the origin.
let small_grid = Grid::<i128>::new(SMALL_SCALE * 1_000.0, 0.0);
let small_grid = Grid::<i128>::new(PROTON_DIA * 5_000.0, 0.0);
commands.spawn_big_space(small_grid, |root_grid| {
root_grid.spawn_spatial(DirectionalLight::default());
// A carbon atom at the origin
// A proton at the origin
root_grid.spawn_spatial((
Atom,
Proton,
Mesh3d(meshes.add(Sphere::default())),
MeshMaterial3d(materials.add(Color::WHITE)),
Transform::from_scale(Vec3::splat(SMALL_SCALE)),
Transform::from_scale(Vec3::splat(PROTON_DIA)),
));
// Compute the grid cell for the far away objects
let (grid_cell, cell_offset) = root_grid
.grid()
.translation_to_grid(DVec3::X * BIG_DISTANCE);
.translation_to_grid(DVec3::X * UNIVERSE_DIA);
// A carbon atom at the other side of the milky way
// A proton at the other side of the milky way
root_grid.spawn_spatial((
Atom,
Proton,
Mesh3d(meshes.add(Sphere::default())),
MeshMaterial3d(materials.add(Color::WHITE)),
Transform::from_translation(cell_offset).with_scale(Vec3::splat(SMALL_SCALE)),
Transform::from_translation(cell_offset).with_scale(Vec3::splat(PROTON_DIA)),
grid_cell,
));
root_grid.spawn_spatial((
Camera3d::default(),
Projection::Perspective(PerspectiveProjection {
near: SMALL_SCALE * 0.01, // Without this, the atom would be clipped
near: PROTON_DIA * 0.01, // Without this, the atom would be clipped
..Default::default()
}),
Transform::from_xyz(0.0, 0.0, SMALL_SCALE * 2.0),
Transform::from_xyz(0.0, 0.0, PROTON_DIA * 2.0),
grid_cell,
FloatingOrigin,
big_space::camera::CameraController::default(),
@ -88,13 +88,13 @@ fn setup_scene(
});
commands.spawn(Text::new(format!(
"Press `T` to teleport between the origin and ship {BIG_DISTANCE}m away."
"Press `T` to teleport between the origin and ship {UNIVERSE_DIA}m away."
)));
}
fn bounce_atoms(mut atoms: Query<&mut Transform, With<Atom>>, time: Res<Time>) {
fn bounce_atoms(mut atoms: Query<&mut Transform, With<Proton>>, time: Res<Time>) {
for mut atom in atoms.iter_mut() {
atom.translation.y = time.elapsed_secs().sin() * SMALL_SCALE;
atom.translation.y = time.elapsed_secs().sin() * PROTON_DIA;
}
}
@ -103,14 +103,21 @@ fn toggle_cam_pos(
mut toggle: Local<bool>,
grid: Query<&Grid<i128>>,
keyboard: Res<ButtonInput<KeyCode>>,
protons: Query<&GlobalTransform, With<Proton>>,
) {
if !keyboard.just_pressed(KeyCode::KeyT) {
return;
}
*cam.single_mut() = if *toggle {
grid.single().translation_to_grid(DVec3::X * BIG_DISTANCE).0
grid.single().translation_to_grid(DVec3::X * UNIVERSE_DIA).0
} else {
GridCell::ZERO
};
*toggle = !*toggle;
// To prove there is no funny business going on, let's print out the `GlobalTransform` of each
// of the protons, to show that they truly are as far apart as we say they are.
info!("Width of observable universe: {UNIVERSE_DIA}");
for proton in &protons {
info!("Proton x coord: {}", proton.translation().x);
}
}