How to Access Object Details within Rhinoscript or Python Script

Hi all,
I’m trying to write a script that is able to see and output part of the object details that are shown when I click the “Details” button in the properties tab. I’m specifically looking for it to output the object description from the geometry section. The goal of the script is to quickly see whether a bunch of arcs are NURBS arcs or standard arcs. This is helpful for me to know when exporting to DXF.



Hi @jodanvids,

Let me know if this helps any.

# Test for a curve that is or looks like an arc
def _is_arc(curve):
    closed = False
    rc = curve is None
    # Is curve an ArcCurve?
    if not rc:
        rc = isinstance(curve, Rhino.Geometry.ArcCurve)
        if rc:
            closed = curve.IsCompleteCircle
    # Is curve a PolyCurve that looks like an arc?
    if not rc:
        if isinstance(curve, Rhino.Geometry.PolyCurve):
            rc, arc = curve.TryGetArc()
            if rc:
                closed = arc.IsCircle
    # Is curve a NurbsCurve that looks like an arc?
    if not rc:
        if isinstance(curve, Rhino.Geometry.NurbsCurve):
            rc, arc = curve.TryGetArc()
            if rc:
                closed = arc.IsCircle
    # Done
    return rc, closed

– Dale

1 Like

Thanks! I think this is what I’m looking for, but I’ll work on it a bit.

Hi Dale,
One other question on this. How do I select the curve to input into the isinstance function. It doesn’t seem to be looking for the object ID obtained from rs.GetObject. It wants the type of data you get from initializing an object through Rhino.Geomtry.Arc for instance.



Hi @jodanvids,

Try this:

import Rhino
import scriptcontext as sc

def test():
    filter = Rhino.DocObjects.ObjectType.Curve
    rc, objref = Rhino.Input.RhinoGet.GetOneObject("Select curve", False, filter)
    if not objref or rc != Rhino.Commands.Result.Success: 

    rc, closed =_is_arc(curve)
    if rc:
        if closed:
            print("Curve is a circle")
            print("Curve is an arc")

– Dale

Hey Dale,
I found a simple solution for this. There is actually a method in Rhino Script that does this, which is Rhino.IsNurbsCurve(). I checked it and it works for distinguishing between an actual arc and a NURBS curve that approximates an arc.

This is the test script I used.

Option Explicit

Call Main()
Sub Main()

	Dim strArcEval
	Dim strDescription
	Dim boolIsArc
	strArcEval = Rhino.GetObject("Select curves for evaluation")
	strDescription = Rhino.ObjectDescription(strArcEval)
	boolIsArc = Rhino.IsNurbsCurve(strArcEval)

End Sub