mirror of
https://github.com/bevyengine/bevy
synced 2024-11-23 13:13:49 +00:00
7989cb2650
# 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.
92 lines
3.1 KiB
Rust
92 lines
3.1 KiB
Rust
//! Creates a hierarchy of parents and children entities.
|
|
|
|
use std::f32::consts::*;
|
|
|
|
use bevy::prelude::*;
|
|
|
|
fn main() {
|
|
App::new()
|
|
.add_plugins(DefaultPlugins)
|
|
.add_startup_system(setup)
|
|
.add_system(rotate)
|
|
.run();
|
|
}
|
|
|
|
fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
|
|
commands.spawn(Camera2dBundle::default());
|
|
let texture = asset_server.load("branding/icon.png");
|
|
|
|
// Spawn a root entity with no parent
|
|
let parent = commands
|
|
.spawn(SpriteBundle {
|
|
transform: Transform::from_scale(Vec3::splat(0.75)),
|
|
texture: texture.clone(),
|
|
..default()
|
|
})
|
|
// With that entity as a parent, run a lambda that spawns its children
|
|
.with_children(|parent| {
|
|
// parent is a ChildBuilder, which has a similar API to Commands
|
|
parent.spawn(SpriteBundle {
|
|
transform: Transform::from_xyz(250.0, 0.0, 0.0).with_scale(Vec3::splat(0.75)),
|
|
texture: texture.clone(),
|
|
sprite: Sprite {
|
|
color: Color::BLUE,
|
|
..default()
|
|
},
|
|
..default()
|
|
});
|
|
})
|
|
// Store parent entity for next sections
|
|
.id();
|
|
|
|
// Another way is to use the push_children function to add children after the parent
|
|
// entity has already been spawned.
|
|
let child = commands
|
|
.spawn(SpriteBundle {
|
|
transform: Transform::from_xyz(0.0, 250.0, 0.0).with_scale(Vec3::splat(0.75)),
|
|
texture,
|
|
sprite: Sprite {
|
|
color: Color::GREEN,
|
|
..default()
|
|
},
|
|
..default()
|
|
})
|
|
.id();
|
|
|
|
// Add child to the parent.
|
|
commands.entity(parent).add_child(child);
|
|
}
|
|
|
|
// A simple system to rotate the root entity, and rotate all its children separately
|
|
fn rotate(
|
|
mut commands: Commands,
|
|
time: Res<Time>,
|
|
mut parents_query: Query<(Entity, &Children), With<Sprite>>,
|
|
mut transform_query: Query<&mut Transform, With<Sprite>>,
|
|
) {
|
|
for (parent, children) in &mut parents_query {
|
|
if let Ok(mut transform) = transform_query.get_mut(parent) {
|
|
transform.rotate_z(-PI / 2. * time.delta_seconds());
|
|
}
|
|
|
|
// To iterate through the entities children, just treat the Children component as a Vec
|
|
// Alternatively, you could query entities that have a Parent component
|
|
for child in children {
|
|
if let Ok(mut transform) = transform_query.get_mut(*child) {
|
|
transform.rotate_z(PI * time.delta_seconds());
|
|
}
|
|
}
|
|
|
|
// To demonstrate removing children, we'll remove a child after a couple of seconds.
|
|
if time.elapsed_seconds() >= 2.0 && children.len() == 2 {
|
|
let child = children.last().unwrap();
|
|
commands.entity(*child).despawn_recursive();
|
|
}
|
|
|
|
if time.elapsed_seconds() >= 4.0 {
|
|
// This will remove the entity from its parent's list of children, as well as despawn
|
|
// any children the entity has.
|
|
commands.entity(parent).despawn_recursive();
|
|
}
|
|
}
|
|
}
|