TrackingBone3D_head.gd

   1 @tool
   2
   3 class_name TrackingBone3D_head
   4 extends SkeletonModifier3D
   5
   6 @export_enum(" ") var bone: String
   7 @export var target: Vector3 = Vector3(0, 0, 0)
   8 @export var influence_lerp_seconds: float = 0.5
   9 @export var rotation_lerp_weight: float = 0.5
  10
  11 var _skeleton: Skeleton3D
  12 var _bone_idx: int
  13
  14 var old_current_pose: Transform3D = Transform3D.IDENTITY
  15
  16 func _validate_property(property: Dictionary) -> void:
  17         if property.name == "bone":
  18                 var skeleton: Skeleton3D = get_skeleton()
  19                 if skeleton:
  20                         property.hint = PROPERTY_HINT_ENUM
  21                         property.hint_string = skeleton.get_concatenated_bone_names()
  22
  23
  24 func _ready() -> void:
  25         # for tweening influence
  26         influence = 0
  27
  28         # for tweening bone poses
  29         _skeleton = get_skeleton()
  30         if not _skeleton:
  31                 push_error("Expected a skeleton!")
  32         _bone_idx = _skeleton.find_bone(bone)
  33
  34         # for smooth rotations
  35         old_current_pose = _skeleton.global_transform * _skeleton.get_bone_global_pose(_bone_idx)
  36
  37
  38 func tween_influence(goal_weight: float) -> void:
  39         create_tween().tween_method(
  40                 _interpolate_influence, influence, goal_weight, influence_lerp_seconds
  41                 ).set_trans(Tween.TRANS_EXPO)
  42
  43
  44 func _interpolate_influence(weight: float) -> void:
  45         influence = weight
  46
  47
  48
  49 func _process_modification() -> void:
  50         var current_pose: Transform3D = _skeleton.global_transform * _skeleton.get_bone_global_pose(_bone_idx)
  51         current_pose.basis = old_current_pose.basis
  52         var target_pose: Transform3D  = current_pose.looking_at(target, Vector3.UP)
  53
  54         # TODO: replace this specific code with general purpose modifier
  55         var axis: Vector3 = target_pose.basis.y
  56         target_pose = target_pose.rotated(axis, PI)
  57
  58         # https://docs.godotengine.org/en/latest/tutorials/3d/using_transforms.html#interpolating-with-quaternions
  59         if rotation_lerp_weight > 0:
  60                 var from := Quaternion(current_pose.basis.orthonormalized())
  61                 var to := Quaternion(target_pose.basis.orthonormalized())
  62                 var rot_target := from.slerp(to, rotation_lerp_weight)
  63                 target_pose.basis = Basis(rot_target)
  64
  65         # remember this!
  66         old_current_pose = target_pose
  67
  68         # yield until target pose has changed, then apply it?
  69         _skeleton.set_bone_global_pose(
  70                 _bone_idx,
  71                 Transform3D(
  72                         (_skeleton.global_transform.affine_inverse() * target_pose).basis.orthonormalized(),
  73                         _skeleton.get_bone_global_pose(_bone_idx).origin
  74                         )
  75                 )