bevy/examples/app/headless.rs
Zachary Harrold 3c829d7f68
Remove everything except Instant from bevy_utils::time (#17158)
# Objective

- Contributes to #11478
- Contributes to #16877

## Solution

- Removed everything except `Instant` from `bevy_utils::time`

## Testing

- CI

---

## Migration Guide

If you relied on any of the following from `bevy_utils::time`:

- `Duration`
- `TryFromFloatSecsError`

Import these directly from `core::time` regardless of platform target
(WASM, mobile, etc.)

If you relied on any of the following from `bevy_utils::time`:

- `SystemTime`
- `SystemTimeError`

Instead import these directly from either `std::time` or `web_time` as
appropriate for your target platform.

## Notes

`Duration` and `TryFromFloatSecsError` are both re-exports from
`core::time` regardless of whether they are used from `web_time` or
`std::time`, so there is no value gained from re-exporting them from
`bevy_utils::time` as well. As for `SystemTime` and `SystemTimeError`,
no Bevy internal crates or examples rely on these types. Since Bevy
doesn't have a `Time<Wall>` resource for interacting with wall-time (and
likely shouldn't need one), I think removing these from `bevy_utils`
entirely and waiting for a use-case to justify inclusion is a reasonable
path forward.
2025-01-05 20:36:08 +00:00

63 lines
2.0 KiB
Rust

//! This example shows how to configure the `ScheduleRunnerPlugin` to run your
//! application without windowing. You can completely remove rendering / windowing
//! Plugin code from bevy by making your import look like this in your Cargo.toml.
//!
//! ```toml
//! [dependencies]
//! bevy = { version = "*", default-features = false }
//! # replace "*" with the most recent version of bevy
//! ```
//!
//! And then enabling the features you need.
//! See the full list: <https://docs.rs/bevy/latest/bevy/#cargo-features>
use bevy::{app::ScheduleRunnerPlugin, log::LogPlugin, prelude::*};
use core::time::Duration;
fn main() {
if cfg!(feature = "bevy_window") {
println!("This example is running with the bevy_window feature enabled and will not run headless.");
println!("Disable the default features and rerun the example to run headless.");
println!("To do so, run:");
println!();
println!(" cargo run --example headless --no-default-features");
return;
}
// This app runs once
App::new()
.add_plugins(DefaultPlugins.set(ScheduleRunnerPlugin::run_once()))
.add_systems(Update, hello_world_system)
.run();
// This app loops forever at 60 fps
App::new()
.add_plugins(
DefaultPlugins
.set(ScheduleRunnerPlugin::run_loop(Duration::from_secs_f64(
1.0 / 60.0,
)))
// The log and ctrl+c plugin can only be registered once globally,
// which means we need to disable it here, because it was already registered with the
// app that runs once.
.disable::<LogPlugin>(),
)
.add_systems(Update, counter)
.run();
}
fn hello_world_system() {
println!("hello world");
}
fn counter(mut state: Local<CounterState>) {
if state.count % 60 == 0 {
println!("{}", state.count);
}
state.count += 1;
}
#[derive(Default)]
struct CounterState {
count: u32,
}