no_std compatibility

[Jondolf]

Objective

Add no_std compatibility.

Solution

TODO

---

Migration Guide

TODO

[tapmondev]

I'm not sure if this is the right place to document this, but I'm trying to run this pr in a pretty confined WASM env , where there is no time/rng access. I'm running into the following error:

2025-04-17T20:57:46.512Z panicC:\Users\tapmondev\.cargo\registry\src\index.crates.io-1949cf8c6b5b557f\bevy_ecs-0.16.0-rc.5\src\error\handler.rs:141: Encountered an error in system `bevy_transform_interpolation::hermite::ease_rotation_hermite<avian2d::interpolation::AngVelSource>`: Parameter `Res<Time<Fixed>>` failed validation: Resource does not exist

I'm running with bevy 0.16 rc5 and these plugins:

  let mut app = App::new();
    app.add_plugins(
        (
            // Use MinimalPlugins and disable features not needed for server-side logic.
            MinimalPlugins
            .build()
            .disable::<ScheduleRunnerPlugin>() // No need for Bevy to run its own schedule loop
            .disable::<TimePlugin>(), // SpacetimeDB handles time/ticks
            PhysicsPlugins::default(),
        )
    );

I manually call the bevy update by running app.update()

From what my gut tells me I can't use the default Physics Plugins, as there is the PhysicsSchedulePlugin ? I'm pretty to new bevy and rust in general. So not sure if I'm missing something obvious here. I'd love some pointers how to call updates to the physics system/world.

EDIT:

I got it running, I was able to use the time plugin by calling:

  unsafe {
        bevy_platform::time::Instant::set_elapsed(get_tick_based_elapsed_time);
    }
    
// --- Tick-Based Elapsed Time Tracking ---
const TICK_INTERVAL_NANOS: u64 = 16_000_000; // 16ms in nanoseconds
static ELAPSED_NANOS: AtomicU64 = AtomicU64::new(0);

// Function to provide elapsed time based on ticks
fn get_tick_based_elapsed_time() -> Duration {
    let nanos = ELAPSED_NANOS.load(Ordering::Relaxed);
    Duration::from_nanos(nanos)
}

However one quirk I noticed is that I manually need to init some resources, not sure this is due to no_std support.

app.init_resource::<avian2d::collision::CollisionDiagnostics>();
    app.init_resource::<SolverDiagnostics>();
    app.init_resource::<SpatialQueryDiagnostics>();