mirror of
https://github.com/eliasstepanik/big_space_with_trim.git
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2e69f80b8d
Adds the concept of reference frames, allowing hierarchies of high precision objects, e.g. objects in the reference frame of a planet, which is itself rotating, and orbiting about a star. --------- Co-authored-by: Oliver Scherer <github@oli-obk.de>
101 lines
3.6 KiB
Rust
101 lines
3.6 KiB
Rust
//! This example demonstrates error accumulating from parent to children in nested reference frames.
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use bevy::{math::DVec3, prelude::*};
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use big_space::{
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reference_frame::{ReferenceFrame, RootReferenceFrame},
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FloatingOrigin, GridCell,
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};
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fn main() {
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App::new()
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.add_plugins((
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DefaultPlugins.build().disable::<TransformPlugin>(),
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big_space::FloatingOriginPlugin::<i128>::default(),
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big_space::camera::CameraControllerPlugin::<i128>::default(),
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big_space::debug::FloatingOriginDebugPlugin::<i128>::default(),
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))
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.add_systems(Startup, setup_scene)
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.run()
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}
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// The distance being used to test precision. A sphere is placed at this position, and a child is
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// added in the opposite direction. This should sum to zero if we had infinite precision.
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const DISTANT: DVec3 = DVec3::new(1e17, 0.0, 0.0);
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const ORIGIN: DVec3 = DVec3::new(200.0, 0.0, 0.0);
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fn setup_scene(
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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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root: Res<RootReferenceFrame<i128>>,
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) {
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let mesh_handle = meshes.add(Sphere::new(0.5).mesh());
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let matl_handle = materials.add(StandardMaterial {
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base_color: Color::rgb(0.8, 0.7, 0.6),
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..default()
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});
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// A red sphere located at the origin
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commands.spawn((
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PbrBundle {
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mesh: mesh_handle.clone(),
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material: materials.add(Color::RED),
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transform: Transform::from_translation(ORIGIN.as_vec3()),
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..default()
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},
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GridCell::<i128>::default(),
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));
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let parent = root.translation_to_grid(DISTANT);
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let child = root.translation_to_grid(-DISTANT + ORIGIN);
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commands
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.spawn((
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// A sphere very far from the origin
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PbrBundle {
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mesh: mesh_handle.clone(),
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material: matl_handle.clone(),
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transform: Transform::from_translation(parent.1),
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..default()
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},
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parent.0,
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ReferenceFrame::<i128>::default(),
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))
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.with_children(|parent| {
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// A green sphere that is a child of the sphere very far from the origin. This child is
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// very far from its parent, and should be located exactly at the origin (if there was
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// no floating point error). The distance from the green sphere to the red sphere is the
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// error caused by float imprecision. Note that the sphere does not have any rendering
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// artifacts, its position just has a fixed error.
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parent.spawn((
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PbrBundle {
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mesh: mesh_handle,
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material: materials.add(Color::GREEN),
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transform: Transform::from_translation(child.1),
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..default()
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},
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child.0,
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));
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});
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// light
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commands.spawn((
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DirectionalLightBundle {
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transform: Transform::from_xyz(4.0, -10.0, -4.0),
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..default()
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},
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GridCell::<i128>::default(),
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));
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// camera
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commands.spawn((
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Camera3dBundle {
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transform: Transform::from_translation(ORIGIN.as_vec3() + Vec3::new(0.0, 0.0, 8.0))
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.looking_at(Vec3::ZERO, Vec3::Y),
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..default()
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},
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GridCell::<i128>::default(),
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FloatingOrigin,
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big_space::camera::CameraController::default() // Built-in camera controller
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.with_speed_bounds([10e-18, 10e35])
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.with_smoothness(0.9, 0.8)
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.with_speed(1.0),
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));
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}
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