# McNeel Wiki

### User Tools

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

## Question

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 a script, you can write a subroutine that will. The following example 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.

RhinoScript

```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
Rhino.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))

Loop While Not IsNull(crv_pt)
End Sub```

Python

```import rhinoscriptsyntax as rs

def curvaturecircle():
curve = rs.GetObject("Select curve for curvature measurement", rs.filter.curve, True)
if not curve: return

while True:
crv_pt = rs.GetPointOnCurve(curve, "Select point on curve for curvature measurement")
if not crv_pt: break

crv_t = rs.CurveClosestPoint(curve, crv_pt)
arr = rs.CurveCurvature(curve, crv_t)
if not arr:
print "Unable to compute curve curvature."
break

crv_pl = rs.PlaneFromFrame(arr[0], arr[1], arr[4])
pl = rs.MovePlane(crv_pl, arr[2])