ui: Beginning of UI-related stuff

- UiRoot component
- WindowSize resource and update_window_size system
- UiInventory and UiInventorySlot components
- UiInventory now shows player inventory slots

src/inventory/ui.rs

@@ -0,0 +1,93 @@
+use bevy::prelude::*;
+
+use crate::{inventory::{ActiveInventory, Inventory}, ui::{UiRoot, WindowSize}};
+
+const UI_SLOT_ASSET_PATH: &'static str = "sprites/ui/inventory_slot.png";
+
+#[derive(Component)]
+#[require(Node)]
+pub struct UiInventory;
+
+#[derive(Component)]
+#[require(Node, ImageNode)]
+pub struct UiInventorySlot(UVec2);
+
+fn ui_inventory_bundle(inventory: &Inventory, window_size: &Res<WindowSize>) -> impl Bundle {
+    let window_ratio = window_size.aspect_ratio();
+    let (width, height) = {
+        if window_ratio >= 1. {
+            (auto(), percent(100))
+        } else {
+            (percent(100), auto())
+        }
+    };
+    (
+        UiInventory,
+        Node {
+            align_self: AlignSelf::Center,
+            align_content: AlignContent::Center,
+            display: Display::Grid,
+            width,
+            height,
+            aspect_ratio: Some(inventory.size.x as f32 / inventory.size.y as f32),
+            grid_auto_columns: vec![GridTrack::percent(100. / inventory.size.x as f32)],
+            grid_auto_rows: vec![GridTrack::percent(100. / inventory.size.y as f32)],
+            ..default()
+        },
+    )
+}
+
+fn inventory_slot_bundle(x: u32, y: u32, width: u32, height: u32, image: Handle<Image>) -> impl Bundle {
+    (
+        UiInventorySlot(UVec2::new(x, y)),
+        ImageNode {
+            image,
+            image_mode: NodeImageMode::Stretch,
+            ..default()
+        },
+        Node {
+            width: percent(100.),
+            height: percent(100.),
+            grid_column: GridPlacement::start(x as i16 + 1),
+            grid_row: GridPlacement::start(y as i16 + 1),
+            ..default()
+        },
+    )
+}
+
+pub fn setup_ui_inventory(
+    mut commands: Commands,
+    asset_server: Res<AssetServer>,
+    inventory_query: Query<(&Inventory, Option<&Children>), With<ActiveInventory>>,
+    root_query: Query<Entity, With<UiRoot>>,
+    window_size: Res<WindowSize>,
+) {
+    let Ok(root) = root_query.single() else {
+        error!("Query contains more than one UiRoot");
+        return;
+    };
+    let ui_slot_image: Handle<Image> = asset_server.load(UI_SLOT_ASSET_PATH);
+    for (inventory, _children) in inventory_query {
+        let inventory_entity = commands.spawn(ui_inventory_bundle(inventory, &window_size))
+            .with_children(|commands| {
+                for x in 0..inventory.size.x {
+                    for y in 0..inventory.size.y {
+                        commands.spawn(inventory_slot_bundle(x, y, inventory.size.x, inventory.size.y, ui_slot_image.clone()));
+                    }
+                }
+            }).id();
+        commands.entity(root).add_child(inventory_entity);
+
+        // for simplicity we'll show only first inventory
+        break;
+    }
+}
+
+pub fn clear_ui_inventory(
+    mut commands: Commands,
+    inventory_query: Query<Entity, With<UiInventory>>,
+) {
+    for entity in inventory_query {
+        commands.entity(entity).despawn();
+    }
+}