haulage system WIP

src/entities/cargo/systems.rs

@@ -0,0 +1,55 @@
+//! Cargo systems: carry visual cycling and haul encumbrance.
+
+use bevy::prelude::*;
+
+use crate::entities::cargo::components::{CarryVisualState, HaulSlot};
+use crate::entities::item::inventory::constants::ENCUMBERED_SPEED_MULTIPLIER;
+use crate::entities::item::inventory::InventoryChangedEvent;
+use crate::entities::shared_components::Ambulatory;
+
+/// Cycle the carry visual sprite while the entity's HaulSlot is occupied.
+/// When empty, ensure the normal sprite is restored.
+///
+/// Runs in Update (visual only, no game state change).
+pub fn carry_visual_system(
+    time: Res<Time>,
+    mut query: Query<(&HaulSlot, &mut CarryVisualState, &mut Sprite)>,
+) {
+    for (haul_slot, mut visual, mut sprite) in query.iter_mut() {
+        if haul_slot.is_empty() {
+            if visual.showing_cargo {
+                sprite.image = visual.normal_sprite.clone();
+                visual.showing_cargo = false;
+            }
+            continue;
+        }
+
+        visual.timer.tick(time.delta());
+        if visual.timer.just_finished() {
+            visual.showing_cargo = !visual.showing_cargo;
+            sprite.image = if visual.showing_cargo {
+                visual.carry_sprite.clone()
+            } else {
+                visual.normal_sprite.clone()
+            };
+        }
+    }
+}
+
+/// Apply encumbrance when HaulSlot is occupied, remove when empty.
+/// Fires InventoryChangedEvent so update_encumbrance recalculates walk_speed.
+///
+/// Uses Changed<HaulSlot> so this only runs for entities whose slot changed this frame.
+pub fn haul_encumbrance_system(
+    mut query: Query<(Entity, &HaulSlot, &mut Ambulatory), Changed<HaulSlot>>,
+    mut events: MessageWriter<InventoryChangedEvent>,
+) {
+    for (entity, haul_slot, mut ambulatory) in query.iter_mut() {
+        if haul_slot.is_occupied() {
+            ambulatory.walk_speed = ambulatory.base_walk_speed * ENCUMBERED_SPEED_MULTIPLIER;
+        } else {
+            ambulatory.walk_speed = ambulatory.base_walk_speed;
+        }
+        events.write(InventoryChangedEvent { carrier: entity });
+    }
+}