game: add weapon base and sword

scenes/weapons/weapon_sword_projectile.gd

@@ -0,0 +1,40 @@
+class_name WeaponSwordProjectile
+extends Node2D
+
+@export var speed: float = 500.0
+@export var range: float = 200.0
+@export var target: Node2D
+@export var damage: float
+@export var on_hit_sig: Signal
+
+var _direction: Vector2
+var _traveled: float = 0.0
+var _already_hit: Array[PhysicsBody2D] = []
+
+
+func _ready() -> void:
+	_direction = global_position.direction_to(target.global_position).normalized()
+	_traveled = 0.0
+	rotation = _direction.angle()
+	if _direction.x < 0:
+		rotation += PI
+	var proj_manager = get_tree().get_first_node_in_group(GlobalConst.GROUP_PROJ_MANAGER)
+	if not proj_manager:
+		return
+	reparent(proj_manager, true)
+
+
+func _physics_process(delta: float) -> void:
+	var step = _direction * speed * delta
+	global_position += step
+	_traveled += step.length()
+
+	if _traveled >= range:
+		queue_free()
+
+
+func _on_area_2d_body_entered(body: Node2D) -> void:
+	if body in _already_hit:
+		return
+	on_hit_sig.emit(self, body)
+	_already_hit.append(body)