create unit selector

scripts/main_camera.gd

@@ -57,6 +57,7 @@ func _input(event: InputEvent) -> void:
 		target_position = Vector3.ZERO
 		zoom_raw = ZOOM_VALUE_DEFAULT
 
+
 func _handle_movement(delta: float) -> void:
 	var viewport_size := get_viewport().get_visible_rect().size
 

scripts/selector.gd

@@ -0,0 +1,108 @@
+extends Node
+
+var frustrum_polygon: ConvexPolygonShape3D = ConvexPolygonShape3D.new()
+var frustrum_polygon_points: PackedVector3Array = [
+		Vector3.ZERO,
+		Vector3.UP,
+		Vector3.RIGHT,
+		Vector3.BACK,
+		Vector3.ONE,
+]
+
+var visible_units: Dictionary = {}
+
+var selecting: bool = false
+var selecting2: bool = false
+var selection_rect: Rect2 = Rect2()
+
+@onready var camera: Camera3D = get_viewport().get_camera_3d()
+@onready var frustrum_area: Area3D = $FrustrumArea
+@onready var frustrum_collision_shape: CollisionShape3D = (
+		$FrustrumArea/FrustrumCollisionShape
+)
+@onready var rect_box: Panel = $SelectionRect
+
+
+func _ready() -> void:
+	frustrum_polygon.points = frustrum_polygon_points
+	frustrum_collision_shape.shape = frustrum_polygon
+	rect_box.visible = false
+	frustrum_area.body_entered.connect(_on_frustrum_area_unit_entered)
+	frustrum_area.body_exited.connect(_on_frustrum_area_unit_exited)
+
+
+func _process(_delta: float) -> void:
+	_handle_frustrum_shape()
+	_handle_selection_box()
+	_handle_unit_selection()
+
+
+func _input(event: InputEvent) -> void:
+	if event is InputEventMouseButton:
+		var button_event := event as InputEventMouseButton
+		selecting = button_event.pressed
+		if selecting:
+			selection_rect.position = button_event.position
+			selection_rect.size = Vector2.ZERO
+	
+	if event is InputEventMouseMotion and selecting:
+		var motion_event := event as InputEventMouseMotion
+		selection_rect.size = motion_event.position - selection_rect.position
+
+
+func _handle_frustrum_shape() -> void:
+	var viewport_size := get_viewport().get_visible_rect().size
+
+	var origin := camera.position
+	var far := camera.far - 1
+	var corner_1 := camera.project_position(Vector2.ZERO, far)
+	var corner_2 := camera.project_position(Vector2(viewport_size.x, 0), far)
+	var corner_3 := camera.project_position(Vector2(0, viewport_size.y), far)
+	var corner_4 := camera.project_position(viewport_size, far)
+
+	frustrum_polygon_points[0] = origin
+	frustrum_polygon_points[1] = corner_1
+	frustrum_polygon_points[2] = corner_2
+	frustrum_polygon_points[3] = corner_3
+	frustrum_polygon_points[4] = corner_4
+
+	frustrum_polygon.points = frustrum_polygon_points
+
+
+func _handle_selection_box() -> void:
+	rect_box.visible = selecting
+	if not selecting:
+		return
+	
+	var rect_abs := selection_rect.abs()
+
+	rect_box.position = rect_abs.position
+	rect_box.size = rect_abs.size
+
+
+func _handle_unit_selection() -> void:
+	if not selecting:
+		return
+	
+	var rect_abs := selection_rect.abs()
+
+	for unit: Node3D in visible_units.values():
+		var point := camera.unproject_position(unit.position)
+		if unit is TestUnit:
+			(unit as  TestUnit).set_selected(rect_abs.has_point(point))
+
+
+func _on_frustrum_area_unit_entered(unit: Node3D) -> void:
+	var unit_id := unit.get_instance_id()
+	if visible_units.keys().has(unit_id):
+		return
+	
+	visible_units[unit_id] = unit.get_parent()
+
+
+func _on_frustrum_area_unit_exited(unit: Node3D) -> void:
+	var unit_id := unit.get_instance_id()
+	if !visible_units.keys().has(unit_id):
+		return
+	
+	visible_units.erase(unit_id)