TrackingBone3D.gd

   1 @tool
   2
   3 class_name TrackingBone3D
   4 extends SkeletonModifier3D
   5
   6 enum Axis {
   7         X_plus, Y_plus, Z_plus
   8 }
   9
  10 @export_enum(" ") var bone: String
  11 @export var aim_axis := Axis.Z_plus
  12 @export var pivot_axis := Axis.Y_plus
  13 @export var target: Vector3 = Vector3(0, 0, 0)
  14
  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 _process_modification() -> void:
  25         var skeleton: Skeleton3D = get_skeleton()
  26         if !skeleton:
  27                 return # Never happen, but for the safety.
  28         var bone_idx: int = skeleton.find_bone(bone)
  29         var _parent_idx: int = skeleton.get_bone_parent(bone_idx)
  30         var pose: Transform3D = skeleton.global_transform * skeleton.get_bone_global_pose(bone_idx)
  31
  32         var looked_at: Transform3D = _w_look_at(pose)
  33         #var looked_at: Transform3D = pose.looking_at(target, Vector3.UP)
  34         #var axis: Vector3 = looked_at.basis.y
  35         #looked_at = looked_at.rotated(axis, PI)
  36
  37         skeleton.set_bone_global_pose(
  38                 bone_idx,
  39                 Transform3D(
  40                         (skeleton.global_transform.affine_inverse() * looked_at).basis.orthonormalized(),
  41                         skeleton.get_bone_global_pose(bone_idx).origin
  42                         )
  43                 )
  44
  45
  46 func _w_look_at(from: Transform3D) -> Transform3D:
  47         # y look is default
  48         var w: Vector3 = from.basis.x
  49
  50         if aim_axis == Axis.X_plus:
  51                 w = from.basis.z
  52         elif aim_axis == Axis.Z_plus:
  53                 w = from.basis.y
  54
  55         var t_v: Vector3 = target - from.origin
  56         var v_y: Vector3 = t_v.normalized()
  57         var v_z: Vector3 = w.cross(v_y)
  58         v_z = v_z.normalized()
  59         var v_x: Vector3 = v_y.cross(v_z)
  60         from.basis = Basis(v_x, v_y, v_z)
  61         return from