TrackingBone3D.gd

   1 @tool
   2
   3 class_name TrackingBone3D
   4 extends SkeletonModifier3D
   5
   6 enum Axis {
   7         X_plus, Y_plus, Z_plus, X_minus, Y_minus, Z_minus
   8 }
   9
  10 @export_enum(" ") var bone: String
  11 @export var aim_axis := Axis.Z_plus
  12 @export var target: Vector3 = Vector3(0, 0, 0)
  13
  14 var _skeleton: Skeleton3D
  15 var _bone_idx: int
  16
  17
  18 func _validate_property(property: Dictionary) -> void:
  19         if property.name == "bone":
  20                 var skeleton: Skeleton3D = get_skeleton()
  21                 if skeleton:
  22                         property.hint = PROPERTY_HINT_ENUM
  23                         property.hint_string = skeleton.get_concatenated_bone_names()
  24
  25
  26 func _ready() -> void:
  27         # for tweening bone poses
  28         _skeleton = get_skeleton()
  29         if not _skeleton:
  30                 push_error("Expected a skeleton!")
  31         _bone_idx = _skeleton.find_bone(bone)
  32
  33
  34 func _process_modification() -> void:
  35         var pose: Transform3D = _skeleton.global_transform * _skeleton.get_bone_global_pose(_bone_idx)
  36         var looked_at: Transform3D = _w_look_at(pose)
  37
  38         _skeleton.set_bone_global_pose(
  39                 _bone_idx,
  40                 Transform3D(
  41                         (_skeleton.global_transform.affine_inverse() * looked_at).basis.orthonormalized(),
  42                         _skeleton.get_bone_global_pose(_bone_idx).origin
  43                         )
  44                 )
  45
  46
  47 func _w_look_at(from: Transform3D) -> Transform3D:
  48         var w: Vector3
  49
  50         if aim_axis == Axis.Y_plus:
  51                 w = from.basis.x
  52         elif aim_axis == Axis.X_plus:
  53                 w = from.basis.z
  54         elif aim_axis == Axis.Z_plus:
  55                 w = from.basis.y
  56         elif aim_axis == Axis.Y_minus:
  57                 w = w.inverse()
  58         elif aim_axis == Axis.X_minus:
  59                 w = from.basis.y.inverse()
  60         elif aim_axis == Axis.Z_minus:
  61                 w = from.basis.y.inverse()
  62
  63         var t_v: Vector3 = target - from.origin
  64         var v_y: Vector3 = t_v.normalized()
  65         var v_z: Vector3 = w.cross(v_y)
  66         v_z = v_z.normalized()
  67         var v_x: Vector3 = v_y.cross(v_z)
  68         from.basis = Basis(v_x, v_y, v_z)
  69         return from