Plugins

Plugins bundle related systems and resources into a reusable unit. Each implements Bevy's Plugin trait and is registered in create_app() or run().

OrbitalMechanicsPlugin

Source: src/plugins/orbital_mechanics.rs

The central simulation plugin. Registers Avian3D physics on a custom ManualPhysics schedule (decoupled from the render frame rate), and orchestrates all orbital mechanics and capture systems.

Registers the following on OnEnter(UiScreen::Sim):

• init_sim_resources — inserts Celestials, OrbitalCache, WorldTime, and CaptureSphereRadius
• load_dataset_entities — loads JSON orbital datasets from assets/datasets/

Registers the following on OnExit(UiScreen::Sim):

• remove_sim_resources — removes the above resources

init_orbitals runs in First to ensure newly-spawned Orbit components are initialised before any Update system runs.

fixed_physics_step runs in FixedUpdate at FIXED_HZ and manually drives the ManualPhysics schedule each tick, scaled by WorldTime::multiplier.

The ManualPhysics schedule runs in this order:

Set	Systems
PhysicsSystems::First	cache_eci_states
PhysicsSystems::Prepare	physics_bubble_add_remove, target_entity_reset_origin
(Avian3D default sets)	Broad-phase, narrow-phase, constraint solving, integration
PhysicsSystems::Last	capture_state_machine_update

Also registers dev_gizmos, capture_gizmos, and floating_origin_update_visuals in Update.

pub struct OrbitalMechanicsPlugin;

impl Plugin for OrbitalMechanicsPlugin {
    fn build(&self, app: &mut App) {
        app.add_plugins(PhysicsPlugins::new(ManualPhysics))
            .add_systems(OnEnter(UiScreen::Sim), (init_sim_resources, load_dataset_entities).chain())
            .add_systems(OnExit(UiScreen::Sim), remove_sim_resources)
            .add_systems(First, init_orbitals.run_if(in_state(UiScreen::Sim)))
            .add_systems(FixedUpdate, fixed_physics_step.run_if(in_state(UiScreen::Sim)))
            // ... gizmo + visual update systems in Update
            .add_systems(ManualPhysics, (
                cache_eci_states.in_set(PhysicsSystems::First),
                (physics_bubble_add_remove, target_entity_reset_origin).in_set(PhysicsSystems::Prepare),
                capture_state_machine_update.in_set(PhysicsSystems::Last),
            ).run_if(in_state(UiScreen::Sim)));
    }
}

OrbitCameraPlugin

Source: src/plugins/orbit_camera.rs

Registers three input systems in Update and one tracking system in PostUpdate.

System	Purpose
orbit_camera_input	Handles mouse pan and scroll zoom
orbit_camera_switch_target	Switches tracked entity on click
orbit_camera_control_target	Syncs camera focus to the current target's position
orbit_camera_track	Runs after floating_origin_update_visuals to keep the camera positioned correctly

orbit_camera_track is ordered with .after(floating_origin_update_visuals) to ensure the floating origin translation is applied before the camera is repositioned.

GpuComputePlugin

Source: src/plugins/gpu_compute.rs

Manages a GPU compute pipeline for efficiently rendering large orbital debris datasets (thousands of objects) as instanced points on the map view.

Registers:

• GpuElements, GpuComputeUniforms, GpuComputeEpochOrigin resources on the main world
• GpuEciStateBuffer — a GPU-side ShaderStorageBuffer of ECI state vectors, extracted to the render world each frame
• MapOrbitPointMaterial — a custom Material that reads from the ECI buffer in its vertex shader to position instanced debris points on the map
• A compute pass (GpuComputeLabel) that propagates ECI states on the GPU using orbital_eci.wgsl
• setup_map_orbit_points, update_gpu_uniforms, sync_map_orbit_point_visibility in PostUpdate
• reset_gpu_compute_resources on OnExit(UiScreen::Sim)

The compute pipeline takes the initial ECI state buffer and a time offset uniform, and writes updated positions into the buffer read by the map material. This avoids uploading per-object transforms every frame for large catalogs.

UiPlugin

Source: src/ui/plugin.rs

Responsible for the entire Bevy-native UI layer. Registers:

• A dedicated UiCamera entity on its own render layer (UI_LAYER = 2)
• UiScreen state (WorkingDirectorySetup → Home → Sim state machine)
• SelectedProject, UiTheme, WorkingDirectory, NewCapturePlanForm resources
• UiEvent message type
• Screen lifecycle systems: spawn/cleanup/interaction handlers for WorkingDirectorySetupScreen, HomeScreen, SimScreen, and NewCapturePlanModal
• Input field systems: input_field_interaction, input_field_keyboard, input_field_display
• Form sync system: sync_form_fields
• Polling systems: poll_file_dialog_task, poll_new_plan_modal, poll_home_plan_refresh

State transitions are driven by UiEvent messages processed by handle_ui_events:

Event	Transition
WorkingDirectorySelected(path)	WorkingDirectorySetup → Home
ChangeWorkingDirectory	Home → WorkingDirectorySetup
OpenProject(id)	Home → Sim (only if id exists in CapturePlanLibrary)
BackToHome	Sim → Home

The poll_home_plan_refresh system watches the UserPlansDirty flag. When set, it rebuilds the home screen plan list in-place without triggering a full screen transition.