Generic Way to Create Concentric Shape

GoJS
#1

What is the best way to make concentric shapes? Basic shapes are easy to make concentric shapes, but when there are curves involved, it’s not that easy. Is there a way to make an outer shape, copy it to an inner shape, scale to a small shape, then overlay the inner shape on top (centered) of the outer shape?

Thanks.

#2

I’m not sure that will work. For example:

    myDiagram.nodeTemplate =
      $(go.Node, "Auto",
        { locationSpot: go.Spot.Center, location: new go.Point(0, 0) },
        $(go.Shape, "Club",
          { fill: "white" },
          new go.Binding("scale"))
      );

    var arr = [];
    for (i = 10; i > 0; i--) arr.push({ scale: i/10 });
    myDiagram.model = new go.GraphLinksModel(arr);

results in:
image

As you can see, scaled curves don’t nest in the way I think you are asking for.

#3

I was able to make a concentric arrow shape using some high school math. If I can visualize the bezier curves, I can perform the same transformations similar to the math I used when making the concentric arrow. I’ll post later if I’m successful.