这个要研究。

applyOffset <spline_shape_node>
<offset_float>

For each spline in
the shape, makes a copy of the spline, offset on all sides to the distance in
units specified by offset_float.
If a spline is open, the resulting spline and its outline will make a single
closed spline. Negative offset_float values create an offset spline to the left of the spline (as the spline is drawn from its start to its finish). The spline_shape_node is converted to a SplineShape (Editable Spline) if it is not
already a SplineShape.