use bevy states

despawn plugin
buiding plugin

game/buildings/Cargo.toml

@@ -8,6 +8,8 @@ edition = "2021"
 [dependencies]
 bevy = "0.13.2"
 world_generation = {path = "../../engine/world_generation"}
+shared = {path = "../shared"}
+bevy_rapier3d = "0.26.0"
 
 [features]
 tracing = []

game/buildings/src/building_plugin.rs

@@ -0,0 +1,68 @@
+use bevy::{prelude::*, window::PrimaryWindow};
+use bevy_rapier3d::{pipeline::QueryFilter, plugin::RapierContext};
+use shared::{despawn::Despawn, states::GameplayState, tags::MainCamera};
+use world_generation::{hex_utils::HexCoord, map::map::Map};
+
+pub struct BuildingPugin;
+
+impl Plugin for BuildingPugin {
+	fn build(&self, app: &mut App) {
+		app.add_systems(Startup, init);
+		app.add_systems(Update, hq_placement.run_if(in_state(GameplayState::PlaceHQ)));
+	}
+}
+
+#[derive(Resource)]
+struct IndicatorCube(Handle<Mesh>, Handle<StandardMaterial>);
+
+fn init(mut commands: Commands, mut meshes: ResMut<Assets<Mesh>>, mut materials: ResMut<Assets<StandardMaterial>>) {
+	let cube = Cuboid::from_size(Vec3::splat(1.));
+	let mesh_handle = meshes.add(cube);
+	let mat_handle = materials.add(Color::WHITE);
+	commands.insert_resource(IndicatorCube(mesh_handle, mat_handle));
+}
+
+fn hq_placement(
+	cam_query: Query<(&GlobalTransform, &Camera), With<MainCamera>>,
+	mut commands: Commands,
+	window: Query<&Window, With<PrimaryWindow>>,
+	mouse: Res<ButtonInput<MouseButton>>,
+	rapier_context: Res<RapierContext>,
+	map: Res<Map>,
+	indicator: Res<IndicatorCube>,
+) {
+	let win = window.single();
+	let (cam_transform, camera) = cam_query.single();
+	let Some(cursor_pos) = win.cursor_position() else {
+		return;
+	};
+
+	let Some(cam_ray) = camera.viewport_to_world(cam_transform, cursor_pos) else {
+		return;
+	};
+
+	let collision = rapier_context.cast_ray(
+		cam_ray.origin,
+		cam_ray.direction.into(),
+		500.,
+		true,
+		QueryFilter::only_fixed(),
+	);
+
+	if let Some((_e, dist)) = collision {
+		let contact_point = cam_ray.get_point(dist);
+		let contact_coord = HexCoord::from_world_pos(contact_point);
+		let positions = map.hex_select(&contact_coord, 3, true, |pos, h, _| pos.to_world(h));
+		for p in positions {
+			commands.spawn((
+				PbrBundle {
+					mesh: indicator.0.clone(),
+					material: indicator.1.clone(),
+					transform: Transform::from_translation(p),
+					..default()
+				},
+				Despawn,
+			));
+		}
+	}
+}

game/buildings/src/lib.rs

@@ -1 +1,4 @@
 pub mod buildings_database;
+pub mod building_plugin;
+
+pub use building_plugin::*;