@tool

class_name TrackingBone3D_head
extends SkeletonModifier3D

@export_enum(" ") var bone: String
@export var target: Vector3 = Vector3(0, 0, 0)


func _validate_property(property: Dictionary) -> void:
	if property.name == "bone":
		var skeleton: Skeleton3D = get_skeleton()
		if skeleton:
			property.hint = PROPERTY_HINT_ENUM
			property.hint_string = skeleton.get_concatenated_bone_names()


func _process_modification() -> void:
	var skeleton: Skeleton3D = get_skeleton()
	if !skeleton:
		return # Never happen, but for the safety.
	var bone_idx: int = skeleton.find_bone(bone)
	var _parent_idx: int = skeleton.get_bone_parent(bone_idx)
	var pose: Transform3D = skeleton.global_transform * skeleton.get_bone_global_pose(bone_idx)
	
	#var looked_at: Transform3D = _w_look_at(pose, target)
	var looked_at: Transform3D = pose.looking_at(target, Vector3.UP)
	var axis: Vector3 = looked_at.basis.y
	looked_at = looked_at.rotated(axis, PI)
	
	skeleton.set_bone_global_pose(
		bone_idx,
		Transform3D(
			(skeleton.global_transform.affine_inverse() * looked_at).basis.orthonormalized(), 
			skeleton.get_bone_global_pose(bone_idx).origin
			)
		)