Creating a super elipses featurescript

Michael_Goldblatt

Super elipses for reference: http://demonstrations.wolfram.com/VisualizingSuperellipses/

I'm trying to create a superelipses featurescript, but am having some trouble getting the shape to behave the way I want. 
The two solutions I can think of are to 1) make geometry and then constrain it (so that the corner fillets are tangent to the rest of the arcs) in featurescript.
or 2) to make a sketch that will plot equations with a selected origin. 

"The superellipse has parametric equations , ,

 for  in the first quadrant (, ); multiplying by  gives the equations for the curve in the other quadrants."

Any insight would be great.

ilya_baran

I think the best way is to make a sketch.  Calculate the points all around the superellipse explicitly and use a single skFitSpline call (or if the superellipse has four sharp corners, use four skFitSpline calls).  Let me know if that's enough to get you through or if more info is needed.

Michael_Goldblatt

ilya_baran said:

I think the best way is to make a sketch.  Calculate the points all around the superellipse explicitly and use a single skFitSpline call (or if the superellipse has four sharp corners, use four skFitSpline calls).  Let me know if that's enough to get you through or if more info is needed.

That is what I ended up trying to do. Actually stuck now on skfitspline. I get no errors but it won't create the geometry.
This is what I have:

  skFitSpline(sketch, "spline", {

          "points" : [

              point1,point2,point3,point4,point5,point6,point7,point8,point1

          ]

  });

Where the points are skPoint that I can see.

Thanks

Michael_Goldblatt

Woops just figured it out. My spline was crossing over itself.

ilya_baran

For reference, here's my attempt: https://cad.onshape.com/documents/79dbbeb51f35887c803024ea/w/7a0e243d4c22fe97f0673b18/e/77e013e2655245fee378e7b4

mahir

Very nice, Ilya. I did something similar in SW. I'm currently working on a more versatile parametric XYZ curve, but I'm having trouble getting FeatureScript to evaluate string expressions as values, e.g. "tan(45)" should evaluate to 1.

ilya_baran

@mahir_abrahim
Unfortunately I think having the feature user input the equation is very difficult to do for now, since we don't allow much even in the isAnything input and FS isn't great for string parsing.  We will need to do a bit of work on our side to make this possible...