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: Node3D = null
  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         if target == null:
  36                 return
  37
  38         var pose: Transform3D = _skeleton.global_transform * _skeleton.get_bone_global_pose(_bone_idx)
  39         var looked_at: Transform3D = _w_look_at(pose)
  40
  41         _skeleton.set_bone_global_pose(
  42                 _bone_idx,
  43                 Transform3D(
  44                         (_skeleton.global_transform.affine_inverse() * looked_at).basis.orthonormalized(),
  45                         _skeleton.get_bone_global_pose(_bone_idx).origin
  46                         )
  47                 )
  48
  49
  50 func _w_look_at(from: Transform3D) -> Transform3D:
  51         var w: Vector3
  52
  53         if aim_axis == Axis.Y_plus:
  54                 w = from.basis.x
  55         elif aim_axis == Axis.X_plus:
  56                 w = from.basis.z
  57         elif aim_axis == Axis.Z_plus:
  58                 w = from.basis.y
  59         elif aim_axis == Axis.Y_minus:
  60                 w = w.inverse()
  61         elif aim_axis == Axis.X_minus:
  62                 w = from.basis.y.inverse()
  63         elif aim_axis == Axis.Z_minus:
  64                 w = from.basis.y.inverse()
  65
  66         var t_v: Vector3 = target.global_position - from.origin
  67         var v_y: Vector3 = t_v.normalized()
  68         var v_z: Vector3 = w.cross(v_y)
  69         v_z = v_z.normalized()
  70         var v_x: Vector3 = v_y.cross(v_z)
  71         from.basis = Basis(v_x, v_y, v_z)
  72         return from