Blender mesh.hide_backface JP

import bmesh, math, mathutils
class hide_backface(bpy.types.Operator):
    bl_idname = _common.get_ops_idname('mesh', 'hide_backface')
    bl_label = "裏側を隠す"
    bl_options = {'REGISTER', 'UNDO'}

    show_radian = bpy.props.FloatProperty(name="表示角度", default=math.radians(110), min=0, max=math.radians(180), soft_min=0, soft_max=math.radians(180), step=500, precision=0, subtype='ANGLE', unit='ROTATION')

    @classmethod
    def poll(cls, context):
        try:
            ob = context.active_object
            if ob.mode != 'EDIT' or ob.type != 'MESH': return False
        except: return False
        return True

    def execute(self, context):
        ob, me = context.active_object, context.active_object.data
        bm = bmesh.from_edit_mesh(me)

        view_rotation = context.region_data.view_rotation.copy()
        up_axis = mathutils.Vector((0, 0, 1))

        for vert in bm.verts:
            normal_rotation = up_axis.rotation_difference(ob.matrix_world * vert.normal)
            diff_rotation = view_rotation.rotation_difference(normal_rotation)
            vert.hide_set(self.show_radian < diff_rotation.angle)

        bmesh.update_edit_mesh(me)
        return {'FINISHED'}