user: Describe PoseBone(bpy_struct) from the Blender manual or Python API, including usage steps and snippets.

assistant: # PoseBone(bpy_struct)

base class — [`bpy_struct`](bpy.types.bpy_struct.html#bpy.types.bpy_struct "bpy.types.bpy_struct")

*class* bpy.types.PoseBone(*bpy_struct*)
:   Channel defining pose data for a bone in a Pose

    bbone_curveinx
    :   X-axis handle offset for start of the B-Bone’s curve, adjusts curvature

        Type:
        :   float in [-inf, inf], default 0.0

    bbone_curveinz
    :   Z-axis handle offset for start of the B-Bone’s curve, adjusts curvature

        Type:
        :   float in [-inf, inf], default 0.0

    bbone_curveoutx
    :   X-axis handle offset for end of the B-Bone’s curve, adjusts curvature

        Type:
        :   float in [-inf, inf], default 0.0

    bbone_curveoutz
    :   Z-axis handle offset for end of the B-Bone’s curve, adjusts curvature

        Type:
        :   float in [-inf, inf], default 0.0

    bbone_custom_handle_end
    :   Bone that serves as the end handle for the B-Bone curve

        Type:
        :   [`PoseBone`](#bpy.types.PoseBone "bpy.types.PoseBone"), (readonly)

    bbone_custom_handle_start
    :   Bone that serves as the start handle for the B-Bone curve

        Type:
        :   [`PoseBone`](#bpy.types.PoseBone "bpy.types.PoseBone"), (readonly)

    bbone_easein
    :   Length of first Bézier Handle (for B-Bones only)

        Type:
        :   float in [-inf, inf], default 0.0

    bbone_easeout
    :   Length of second Bézier Handle (for B-Bones only)

        Type:
        :   float in [-inf, inf], default 0.0

    bbone_rollin
    :   Roll offset for the start of the B-Bone, adjusts twist

        Type:
        :   float in [-inf, inf], default 0.0

    bbone_rollout
    :   Roll offset for the end of the B-Bone, adjusts twist

        Type:
        :   float in [-inf, inf], default 0.0

    bbone_scalein
    :   Scale factors for the start of the B-Bone, adjusts thickness (for tapering effects)

        Type:
        :   [`mathutils.Vector`](mathutils.html#mathutils.Vector "mathutils.Vector") of 3 items in [-inf, inf], default (1.0, 1.0, 1.0)

    bbone_scaleout
    :   Scale factors for the end of the B-Bone, adjusts thickness (for tapering effects)

        Type:
        :   [`mathutils.Vector`](mathutils.html#mathutils.Vector "mathutils.Vector") of 3 items in [-inf, inf], default (1.0, 1.0, 1.0)

    bone
    :   Bone associated with this PoseBone

        Type:
        :   [`Bone`](bpy.types.Bone.html#bpy.types.Bone "bpy.types.Bone"), (readonly, never None)

    child
    :   Child of this pose bone

        Type:
        :   [`PoseBone`](#bpy.types.PoseBone "bpy.types.PoseBone"), (readonly)

    color
    :   Type:
        :   [`BoneColor`](bpy.types.BoneColor.html#bpy.types.BoneColor "bpy.types.BoneColor"), (readonly)

    constraints
    :   Constraints that act on this pose channel

        Type:
        :   [`PoseBoneConstraints`](bpy.types.PoseBoneConstraints.html#bpy.types.PoseBoneConstraints "bpy.types.PoseBoneConstraints") [`bpy_prop_collection`](bpy.types.bpy_prop_collection.html#bpy.types.bpy_prop_collection "bpy.types.bpy_prop_collection") of [`Constraint`](bpy.types.Constraint.html#bpy.types.Constraint "bpy.types.Constraint"), (readonly)

    custom_shape
    :   Object that defines custom display shape for this bone

        Type:
        :   [`Object`](bpy.types.Object.html#bpy.types.Object "bpy.types.Object")

    custom_shape_rotation_euler
    :   Adjust the rotation of the custom shape

        Type:
        :   [`mathutils.Euler`](mathutils.html#mathutils.Euler "mathutils.Euler") rotation of 3 items in [-inf, inf], default (0.0, 0.0, 0.0)

    custom_shape_scale_xyz
    :   Adjust the size of the custom shape

        Type:
        :   [`mathutils.Vector`](mathutils.html#mathutils.Vector "mathutils.Vector") of 3 items in [-inf, inf], default (1.0, 1.0, 1.0)

    custom_shape_transform
    :   Bone that defines the display transform of this custom shape

        Type:
        :   [`PoseBone`](#bpy.types.PoseBone "bpy.types.PoseBone")

    custom_shape_translation
    :   Adjust the location of the custom shape

        Type:
        :   [`mathutils.Vector`](mathutils.html#mathutils.Vector "mathutils.Vector") of 3 items in [-inf, inf], default (0.0, 0.0, 0.0)

    custom_shape_wire_width
    :   Adjust the line thickness of custom shapes

        Type:
        :   float in [1, 16], default 0.0

    head
    :   Location of head of the channel’s bone

        Type:
        :   [`mathutils.Vector`](mathutils.html#mathutils.Vector "mathutils.Vector") of 3 items in [-inf, inf], default (0.0, 0.0, 0.0), (readonly)

    hide
    :   Bone is not visible except for Edit Mode

        Type:
        :   boolean, default False

    ik_linear_weight
    :   Weight of scale constraint for IK

        Type:
        :   float in [0, 1], default 0.0

    ik_max_x
    :   Maximum angles for IK Limit

        Type:
        :   float in [0, 3.14159], default 0.0

    ik_max_y
    :   Maximum angles for IK Limit

        Type:
        :   float in [0, 3.14159], default 0.0

    ik_max_z
    :   Maximum angles for IK Limit

        Type:
        :   float in [0, 3.14159], default 0.0

    ik_min_x
    :   Minimum angles for IK Limit

        Type:
        :   float in [-3.14159, 0], default 0.0

    ik_min_y
    :   Minimum angles for IK Limit

        Type:
        :   float in [-3.14159, 0], default 0.0

    ik_min_z
    :   Minimum angles for IK Limit

        Type:
        :   float in [-3.14159, 0], default 0.0

    ik_rotation_weight
    :   Weight of rotation constraint for IK

        Type:
        :   float in [0, 1], default 0.0

    ik_stiffness_x
    :   IK stiffness around the X axis

        Type:
        :   float in [0, 0.99], default 0.0

    ik_stiffness_y
    :   IK stiffness around the Y axis

        Type:
        :   float in [0, 0.99], default 0.0

    ik_stiffness_z
    :   IK stiffness around the Z axis

        Type:
        :   float in [0, 0.99], default 0.0

    ik_stretch
    :   Allow scaling of the bone for IK

        Type:
        :   float in [0, 1], default 0.0

    is_in_ik_chain
    :   Is part of an IK chain

        Type:
        :   boolean, default False, (readonly)

    length
    :   Length of the bone

        Type:
        :   float in [-inf, inf], default 0.0, (readonly)

    location
    :   Type:
        :   [`mathutils.Vector`](mathutils.html#mathutils.Vector "mathutils.Vector") of 3 items in [-inf, inf], default (0.0, 0.0, 0.0)

    lock_ik_x
    :   Disallow movement around the X axis

        Type:
        :   boolean, default False

    lock_ik_y
    :   Disallow movement around the Y axis

        Type:
        :   boolean, default False

    lock_ik_z
    :   Disallow movement around the Z axis

        Type:
        :   boolean, default False

    lock_location
    :   Lock editing of location when transforming

        Type:
        :   boolean array of 3 items, default (False, False, False)

    lock_rotation
    :   Lock editing of rotation when transforming

        Type:
        :   boolean array of 3 items, default (False, False, False)

    lock_rotation_w
    :   Lock editing of ‘angle’ component of four-component rotations when transforming

        Type:
        :   boolean, default False

    lock_rotations_4d
    :   Lock editing of four component rotations by components (instead of as Eulers)

        Type:
        :   boolean, default False

    lock_scale
    :   Lock editing of scale when transforming

        Type:
        :   boolean array of 3 items, default (False, False, False)

    matrix
    :   Final 4×4 matrix after constraints and drivers are applied, in the armature object space

        Type:
        :   [`mathutils.Matrix`](mathutils.html#mathutils.Matrix "mathutils.Matrix") of 4 \* 4 items in [-inf, inf], default ((0.0, 0.0, 0.0, 0.0), (0.0, 0.0, 0.0, 0.0), (0.0, 0.0, 0.0, 0.0), (0.0, 0.0, 0.0, 0.0))

    matrix_basis
    :   Alternative access to location/scale/rotation relative to the parent and own rest bone

        Type:
        :   [`mathutils.Matrix`](mathutils.html#mathutils.Matrix "mathutils.Matrix") of 4 \* 4 items in [-inf, inf], default ((0.0, 0.0, 0.0, 0.0), (0.0, 0.0, 0.0, 0.0), (0.0, 0.0, 0.0, 0.0), (0.0, 0.0, 0.0, 0.0))

    matrix_channel
    :   4×4 matrix of the bone’s location/rotation/scale channels (including animation and drivers) and the effect of bone constraints

        Type:
        :   [`mathutils.Matrix`](mathutils.html#mathutils.Matrix "mathutils.Matrix") of 4 \* 4 items in [-inf, inf], default ((0.0, 0.0, 0.0, 0.0), (0.0, 0.0, 0.0, 0.0), (0.0, 0.0, 0.0, 0.0), (0.0, 0.0, 0.0, 0.0)), (readonly)

    motion_path
    :   Motion Path for this element

        Type:
        :   [`MotionPath`](bpy.types.MotionPath.html#bpy.types.MotionPath "bpy.types.MotionPath"), (readonly)

    name
    :   Type:
        :   string, default “”, (never None)

    parent
    :   Parent of this pose bone

        Type:
        :   [`PoseBone`](#bpy.types.PoseBone "bpy.types.PoseBone"), (readonly)

    rotation_axis_angle
    :   Angle of Rotation for Axis-Angle rotation representation

        Type:
        :   float array of 4 items in [-inf, inf], default (0.0, 0.0, 1.0, 0.0)

    rotation_euler
    :   Rotation in Eulers

        Type:
        :   [`mathutils.Euler`](mathutils.html#mathutils.Euler "mathutils.Euler") rotation of 3 items in [-inf, inf], default (0.0, 0.0, 0.0)

    rotation_mode
    :   The kind of rotation to apply, values from other rotation modes are not used

        Type:
        :   enum in [Object Rotation Mode Items](bpy_types_enum_items/object_rotation_mode_items.html#rna-enum-object-rotation-mode-items), default `'QUATERNION'`

    rotation_quaternion
    :   Rotation in Quaternions

        Type:
        :   [`mathutils.Quaternion`](mathutils.html#mathutils.Quaternion "mathutils.Quaternion") rotation of 4 items in [-inf, inf], default (1.0, 0.0, 0.0, 0.0)

    scale
    :   Type:
        :   [`mathutils.Vector`](mathutils.html#mathutils.Vector "mathutils.Vector") of 3 items in [-inf, inf], default (1.0, 1.0, 1.0)

    select
    :   Bone is selected in Pose Mode

        Type:
        :   boolean, default False

    tail
    :   Location of tail of the channel’s bone

        Type:
        :   [`mathutils.Vector`](mathutils.html#mathutils.Vector "mathutils.Vector") of 3 items in [-inf, inf], default (0.0, 0.0, 0.0), (readonly)

    use_custom_shape_bone_size
    :   Scale the custom object by the bone length

        Type:
        :   boolean, default False

    use_ik_limit_x
    :   Limit movement around the X axis

        Type:
        :   boolean, default False

    use_ik_limit_y
    :   Limit movement around the Y axis

        Type:
        :   boolean, default False

    use_ik_limit_z
    :   Limit movement around the Z axis

        Type:
        :   boolean, default False

    use_ik_linear_control
    :   Apply channel size as IK constraint if stretching is enabled

        Type:
        :   boolean, default False

    use_ik_rotation_control
    :   Apply channel rotation as IK constraint

        Type:
        :   boolean, default False

    use_transform_around_custom_shape
    :   Transform the bone as if it was a child of the Custom Shape Transform bone. This can be useful when combining shape-key and armature deformations.

        Type:
        :   boolean, default False

    use_transform_at_custom_shape
    :   The location and orientation of the Custom Shape Transform bone will be used for transform gizmos and for other transform operators in the 3D Viewport. When disabled, the 3D Viewport will still use the actual bone transform for these, even when the custom bone shape transform is overridden.

        Type:
        :   boolean, default False

    basename
    :   The name of this bone before any `.` character.

        (readonly)

    center
    :   The midpoint between the head and the tail.

        (readonly)

    children
    :   (readonly)

    children_recursive
    :   A list of all children from this bone.

        (readonly)

    children_recursive_basename
    :   Returns a chain of children with the same base name as this bone.
        Only direct chains are supported, forks caused by multiple children
        with matching base names will terminate the function
        and not be returned.

        (readonly)

    parent_recursive
    :   A list of parents, starting with the immediate parent.

        (readonly)

    vector
    :   The direction this bone is pointing.
        Utility function for (tail - head)

        (readonly)

    x_axis
    :   Vector pointing down the x-axis of the bone.

        (readonly)

    y_axis
    :   Vector pointing down the y-axis of the bone.

        (readonly)

    z_axis
    :   Vector pointing down the z-axis of the bone.

        (readonly)

    bl_system_properties_get(*\**, *do_create=False*)
    :   DEBUG ONLY. Internal access to runtime-defined RNA data storage, intended solely for testing and debugging purposes. Do not access it in regular scripting work, and in particular, do not assume that it contains writable data

        Parameters:
        :   **do_create** (*boolean**,* *(**optional**)*) – Ensure that system properties are created if they do not exist yet

        Returns:
        :   The system properties root container, or None if there are no system properties stored in this data yet, and its creation was not requested

        Return type:
        :   [`PropertyGroup`](bpy.types.PropertyGroup.html#bpy.types.PropertyGroup "bpy.types.PropertyGroup")

    evaluate_envelope(*point*)
    :   Calculate bone envelope at given point

        Parameters:
        :   **point** ([`mathutils.Vector`](mathutils.html#mathutils.Vector "mathutils.Vector") of 3 items in [-inf, inf]) – Point, Position in 3d space to evaluate

        Returns:
        :   Factor, Envelope factor

        Return type:
        :   float in [-inf, inf]

    bbone_segment_index(*point*)
    :   Retrieve the index and blend factor of the B-Bone segments based on vertex position

        Parameters:
        :   **point** ([`mathutils.Vector`](mathutils.html#mathutils.Vector "mathutils.Vector") of 3 items in [-inf, inf]) – Point, Vertex position in armature pose space

        Returns:
        :   `index`, The index of the first segment joint affecting the point, int in [-inf, inf]

            `blend_next`, The blend factor between the given and the following joint, float in [-inf, inf]

        Return type:
        :   (int in [-inf, inf], float in [-inf, inf])

    bbone_segment_matrix(*index*, *\**, *rest=False*)
    :   Retrieve the matrix of the joint between B-Bone segments if available

        Parameters:
        :   - **index** (*int in* *[**0**,* *inf**]*) – Index of the segment endpoint
            - **rest** (*boolean**,* *(**optional**)*) – Return the rest pose matrix

        Returns:
        :   The resulting matrix in bone local space

        Return type:
        :   [`mathutils.Matrix`](mathutils.html#mathutils.Matrix "mathutils.Matrix") of 4 \* 4 items in [-inf, inf]

        This example shows how to use B-Bone segment matrices to emulate deformation
        produced by the Armature modifier or constraint when assigned to the given bone
        (without Preserve Volume). The coordinates are processed in armature Pose space:

        ```
        def bbone_deform_matrix(pose_bone, point):
            index, blend_next = pose_bone.bbone_segment_index(point)

            rest1 = pose_bone.bbone_segment_matrix(index, rest=True)
            pose1 = pose_bone.bbone_segment_matrix(index, rest=False)
            deform1 = pose1 @ rest1.inverted()

            # `bbone_segment_index` ensures that index + 1 is always valid
            rest2 = pose_bone.bbone_segment_matrix(index + 1, rest=True)
            pose2 = pose_bone.bbone_segment_matrix(index + 1, rest=False)
            deform2 = pose2 @ rest2.inverted()

            deform = deform1 * (1 - blend_next) + deform2 * blend_next

            return pose_bone.matrix @ deform @ pose_bone.bone.matrix_local.inverted()

        # Armature modifier deforming vertices:
        mesh = bpy.data.objects["Mesh"]
        pose_bone = bpy.data.objects["Armature"].pose.bones["Bone"]

        for vertex in mesh.data.vertices:
            vertex.co = bbone_deform_matrix(pose_bone, vertex.co) @ vertex.co

        # Armature constraint modifying an object transform:
        empty = bpy.data.objects["Empty"]
        matrix = empty.matrix_world

        empty.matrix_world = bbone_deform_matrix(pose_bone, matrix.translation) @ matrix
        ```

    compute_bbone_handles(*\**, *rest=False*, *ease=False*, *offsets=False*)
    :   Retrieve the vectors and rolls coming from B-Bone custom handles

        Parameters:
        :   - **rest** (*boolean**,* *(**optional**)*) – Return the rest pose state
            - **ease** (*boolean**,* *(**optional**)*) – Apply scale from ease values
            - **offsets** (*boolean**,* *(**optional**)*) – Apply roll and curve offsets from bone properties

        Returns:
        :   `handle1`, The direction vector of the start handle in bone local space, [`mathutils.Vector`](mathutils.html#mathutils.Vector "mathutils.Vector") of 3 items in [-inf, inf]

            `roll1`, Roll of the start handle, float in [-inf, inf]

            `handle2`, The direction vector of the end handle in bone local space, [`mathutils.Vector`](mathutils.html#mathutils.Vector "mathutils.Vector") of 3 items in [-inf, inf]

            `roll2`, Roll of the end handle, float in [-inf, inf]

        Return type:
        :   ([`mathutils.Vector`](mathutils.html#mathutils.Vector "mathutils.Vector") of 3 items in [-inf, inf], float in [-inf, inf], [`mathutils.Vector`](mathutils.html#mathutils.Vector "mathutils.Vector") of 3 items in [-inf, inf], float in [-inf, inf])

    parent_index(*parent_test*)
    :   The same as ‘bone in other_bone.parent_recurs