bevy/examples/audio/audio_control.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

68 lines
1.8 KiB
Rust

//! This example illustrates how to load and play an audio file, and control how it's played.
use bevy::{audio::AudioSink, prelude::*};
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_startup_system(setup)
.add_system(update_speed)
.add_system(pause)
.add_system(volume)
.run();
}
fn setup(
mut commands: Commands,
asset_server: Res<AssetServer>,
audio: Res<Audio>,
audio_sinks: Res<Assets<AudioSink>>,
) {
let music = asset_server.load("sounds/Windless Slopes.ogg");
let handle = audio_sinks.get_handle(audio.play(music));
commands.insert_resource(MusicController(handle));
}
#[derive(Resource)]
struct MusicController(Handle<AudioSink>);
fn update_speed(
audio_sinks: Res<Assets<AudioSink>>,
music_controller: Res<MusicController>,
time: Res<Time>,
) {
if let Some(sink) = audio_sinks.get(&music_controller.0) {
sink.set_speed(((time.elapsed_seconds() / 5.0).sin() + 1.0).max(0.1));
}
}
fn pause(
keyboard_input: Res<Input<KeyCode>>,
audio_sinks: Res<Assets<AudioSink>>,
music_controller: Res<MusicController>,
) {
if keyboard_input.just_pressed(KeyCode::Space) {
if let Some(sink) = audio_sinks.get(&music_controller.0) {
if sink.is_paused() {
sink.play();
} else {
sink.pause();
}
}
}
}
fn volume(
keyboard_input: Res<Input<KeyCode>>,
audio_sinks: Res<Assets<AudioSink>>,
music_controller: Res<MusicController>,
) {
if let Some(sink) = audio_sinks.get(&music_controller.0) {
if keyboard_input.just_pressed(KeyCode::Plus) {
sink.set_volume(sink.volume() + 0.1);
} else if keyboard_input.just_pressed(KeyCode::Minus) {
sink.set_volume(sink.volume() - 0.1);
}
}
}