private fun rotate_column(col_id: Int, direction: Int) do
		var col_data = rot_col_buffer
		if col_data.is_empty then for i in [0 .. 4[ do col_data.add(new Array[Int])
		array1d_copy_to(coldata(front_face, col_id), rot_col_buffer[0])
		array1d_copy_to(coldata(top_face, col_id), rot_col_buffer[1])
		array1d_copy_to(coldata(back_face, col_id), rot_col_buffer[2])
		array1d_copy_to(coldata(bottom_face, col_id), rot_col_buffer[3])
		if direction == clock then
			rot_col_buffer.rotate_left
		else if direction == counterclock then
			rot_col_buffer.rotate_right
		else
			abort
		end
		set_coldata(front_face, col_id, rot_col_buffer[0])
		set_coldata(top_face, col_id, rot_col_buffer[1])
		set_coldata(back_face, col_id, rot_col_buffer[2])
		set_coldata(bottom_face, col_id, rot_col_buffer[3])
	end