Initial work on rollback and refactor

src/schedule.rs

@@ -0,0 +1,44 @@
+//! The gameplay frame pipeline.
+//!
+//! Every rollback-simulated system belongs to exactly one of these sets, and
+//! the sets run in the order declared here. Plugins add their systems with
+//! `.in_set(GameplaySet::X)` instead of being threaded into one central
+//! `.chain()`, so a module can schedule its own work without any other module
+//! knowing about it.
+
+use bevy::prelude::*;
+use bevy_ggrs::prelude::*;
+
+#[derive(SystemSet, Debug, Clone, PartialEq, Eq, Hash)]
+pub enum GameplaySet {
+    /// Turn this frame's netcode inputs into per-fighter input state.
+    Input,
+    /// Decide whether the current fighter state hands off to another one.
+    Interrupt,
+    /// Run the fighter state that survived the interrupt pass.
+    StateUpdate,
+    /// Integrate velocities into positions.
+    Physics,
+    /// Resolve the integrated positions against the stage.
+    Collision,
+}
+
+/// Declares the order of [`GameplaySet`] inside [`GgrsSchedule`]. Added by
+/// `GamePlugin` before any plugin that populates the sets.
+pub struct GameplaySchedulePlugin;
+
+impl Plugin for GameplaySchedulePlugin {
+    fn build(&self, app: &mut App) {
+        app.configure_sets(
+            GgrsSchedule,
+            (
+                GameplaySet::Input,
+                GameplaySet::Interrupt,
+                GameplaySet::StateUpdate,
+                GameplaySet::Physics,
+                GameplaySet::Collision,
+            )
+                .chain(),
+        );
+    }
+}