bevy/examples/3d/update_gltf_scene.rs
Cameron 7989cb2650 Add global time scaling (#5752)
# Objective

- Make `Time` API more consistent.
- Support time accel/decel/pause.

## Solution

This is just the `Time` half of #3002. I was told that part isn't controversial.

- Give the "delta time" and "total elapsed time" methods `f32`, `f64`, and `Duration` variants with consistent naming.
- Implement accelerating / decelerating the passage of time.
- Implement stopping time.

---

## Changelog

- Changed `time_since_startup` to `elapsed` because `time.time_*` is just silly.
- Added `relative_speed` and `set_relative_speed` methods.
- Added `is_paused`, `pause`, `unpause` , and methods. (I'd prefer `resume`, but `unpause` matches `Timer` API.)
- Added `raw_*` variants of the "delta time" and "total elapsed time" methods.
- Added `first_update` method because there's a non-zero duration between startup and the first update.

## Migration Guide

- `time.time_since_startup()` -> `time.elapsed()`
- `time.seconds_since_startup()` -> `time.elapsed_seconds_f64()`
- `time.seconds_since_startup_wrapped_f32()` -> `time.elapsed_seconds_wrapped()`

If you aren't sure which to use, most systems should continue to use "scaled" time (e.g. `time.delta_seconds()`). The realtime "unscaled" time measurements (e.g. `time.raw_delta_seconds()`) are mostly for debugging and profiling.
2022-10-22 18:52:29 +00:00

74 lines
2.3 KiB
Rust

//! Update a scene from a glTF file, either by spawning the scene as a child of another entity,
//! or by accessing the entities of the scene.
use bevy::prelude::*;
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_startup_system(setup)
.add_system(move_scene_entities)
.run();
}
#[derive(Component)]
struct MovedScene;
fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
commands.spawn(PointLightBundle {
transform: Transform::from_xyz(4.0, 5.0, 4.0),
..default()
});
commands.spawn(Camera3dBundle {
transform: Transform::from_xyz(1.05, 0.9, 1.5)
.looking_at(Vec3::new(0.0, 0.3, 0.0), Vec3::Y),
..default()
});
// Spawn the scene as a child of this entity at the given transform
commands.spawn(SceneBundle {
transform: Transform::from_xyz(0.0, 0.0, -1.0),
scene: asset_server.load("models/FlightHelmet/FlightHelmet.gltf#Scene0"),
..default()
});
// Spawn a second scene, and add a tag component to be able to target it later
commands.spawn((
SceneBundle {
scene: asset_server.load("models/FlightHelmet/FlightHelmet.gltf#Scene0"),
..default()
},
MovedScene,
));
}
// This system will move all entities that are descendants of MovedScene (which will be all entities spawned in the scene)
fn move_scene_entities(
time: Res<Time>,
moved_scene: Query<Entity, With<MovedScene>>,
children: Query<&Children>,
mut transforms: Query<&mut Transform>,
) {
for moved_scene_entity in &moved_scene {
let mut offset = 0.;
iter_hierarchy(moved_scene_entity, &children, &mut |entity| {
if let Ok(mut transform) = transforms.get_mut(entity) {
transform.translation = Vec3::new(
offset * time.elapsed_seconds().sin() / 20.,
0.,
time.elapsed_seconds().cos() / 20.,
);
offset += 1.0;
}
});
}
}
fn iter_hierarchy(entity: Entity, children_query: &Query<&Children>, f: &mut impl FnMut(Entity)) {
(f)(entity);
if let Ok(children) = children_query.get(entity) {
for child in children.iter().copied() {
iter_hierarchy(child, children_query, f);
}
}
}