utils.py 文件源码

def align_bone_z_axis(obj, bone, vec):
    """ Rolls the bone to align its z-axis as closely as possible to
        the given vector.
        Must be in edit mode.
    """
    bone_e = obj.data.edit_bones[bone]

    vec = bone_e.y_axis.cross(vec)
    vec.normalize()

    dot = max(-1.0, min(1.0, bone_e.x_axis.dot(vec)))
    angle = math.acos(dot)

    bone_e.roll += angle

    dot1 = bone_e.x_axis.dot(vec)

    bone_e.roll -= angle * 2

    dot2 = bone_e.x_axis.dot(vec)

    if dot1 > dot2:
        bone_e.roll += angle * 2