Adding Curvature Circles

Developer: RhinoScript
Summary: Demonstrates how to add curvature circles using RhinoScript.

I find Rhino's Curvature command very useful for analyzing the curvature at a point on a curve. Is there anyway for Rhino to add the circle to the document when I pick on the curve (instead of just drawing it dynamically)?

There is no option on the Curvature command for leaving the circle that it draw dynamically. But, with the help of RhinoScript, you can write a subroutine that will. The following example RhinoScript code demonstrates how to do just this.

Note, if you want to run the following script, just download it. Then, extract the .rvb file from the zip file onto your desktop, and then drag it on top of Rhino and drop it. Finally, run the CurvatureCircle command.

 Option Explicit 
 
 Sub CurvatureCircle
 
   Dim crv, crv_pt, crv_t
   Dim arr, crv_pl, pl
 
   crv = Rhino.GetObject("Select curve for curvature measurement", 4, True)
   If IsNull(crv) Then Exit Sub
 
   Do    
     crv_pt = Rhino.GetPointOnCurve(crv, "Select point on curve for curvature measurement")
     If IsNull(crv_pt) Then Exit Do
 
     crv_t = Rhino.CurveClosestPoint(crv, crv_pt)
     If IsNull(crv_t) Then Exit Do
 
     arr = Rhino.CurveCurvature(crv, crv_t)
     If IsNull(arr) Then 
       RhinoApp().Print("Unable to compute curve curvature.")
       Exit Do
     End If
 
     crv_pl = Rhino.PlaneFromFrame(arr(0), arr(1), arr(4))
     pl = Rhino.MovePlane(crv_pl, arr(2))
 
     Rhino.AddCircle pl, arr(3)
     Rhino.AddPoint arr(0)
   Loop While Not IsNull(crv_pt)
 
 End Sub