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https://github.com/bevyengine/bevy
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# Objective To debug issues like https://github.com/bevyengine/bevy/pull/11169. ## Solution When P is pressed in logs example, call `panic!()`. <img width="1392" alt="Screenshot 2024-01-02 at 01 10 16" src="https://github.com/bevyengine/bevy/assets/28969/a788737e-d23c-43a3-bc68-d6c5b0ab88ad">
82 lines
2.8 KiB
Rust
82 lines
2.8 KiB
Rust
//! This example illustrates how to use logs in bevy.
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use bevy::log::once;
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use bevy::prelude::*;
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fn main() {
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App::new()
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.add_plugins(DefaultPlugins.set(bevy::log::LogPlugin {
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// Uncomment this to override the default log settings:
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// level: bevy::log::Level::TRACE,
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// filter: "wgpu=warn,bevy_ecs=info".to_string(),
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..default()
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}))
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.add_systems(Startup, setup)
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.add_systems(Update, log_system)
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.add_systems(Update, log_once_system)
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.add_systems(Update, panic_on_p)
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.run();
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}
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fn setup(mut commands: Commands) {
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commands.spawn(Camera2dBundle::default());
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commands.spawn(TextBundle {
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text: Text::from_section(
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"Press P to panic",
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TextStyle {
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font_size: 60.0,
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..default()
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},
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),
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..default()
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});
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}
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fn panic_on_p(keys: Res<ButtonInput<KeyCode>>) {
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if keys.just_pressed(KeyCode::KeyP) {
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panic!("P pressed, panicking");
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}
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}
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fn log_system() {
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// here is how you write new logs at each "log level" (in "least important" to "most important"
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// order)
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trace!("very noisy");
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debug!("helpful for debugging");
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info!("helpful information that is worth printing by default");
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warn!("something bad happened that isn't a failure, but thats worth calling out");
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error!("something failed");
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// by default, trace and debug logs are ignored because they are "noisy"
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// you can control what level is logged by setting up the LogPlugin
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// alternatively you can set the log level via the RUST_LOG=LEVEL environment variable
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// ex: RUST_LOG=trace, RUST_LOG=info,bevy_ecs=warn
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// the format used here is super flexible. check out this documentation for more info:
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// https://docs.rs/tracing-subscriber/*/tracing_subscriber/filter/struct.EnvFilter.html
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}
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fn log_once_system() {
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// The 'once' variants of each log level are useful when a system is called every frame,
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// but we still wish to inform the user only once. In other words, use these to prevent spam :)
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trace_once!("one time noisy message");
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debug_once!("one time debug message");
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info_once!("some info which is printed only once");
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warn_once!("some warning we wish to call out only once");
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error_once!("some error we wish to report only once");
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for i in 0..10 {
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info_once!("logs once per call site, so this works just fine: {}", i);
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}
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// you can also use the 'once!' macro directly, in situations you want do do
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// something expensive only once within the context of a continous system.
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once!({
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info!("doing expensive things");
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let mut a: u64 = 0;
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for i in 0..100000000 {
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a += i;
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}
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info!("result of some expensive one time calculation: {}", a);
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});
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}
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