Why doesn't CenterMark work on a closed curve?

Hi Rhino’s. I am perplexed as to why i cant get a center on my closed curves. does anyone know a workaround? i want a mark for the middle of x & y in my curve. i use this for gaining measurements from the “mid” of the closed curve.

Hello- if the curve is planar, use AreaCentroid


Thanks @pascal but that doesn’t give me the mid point, what I want is a mark essentially where the gumball appears. My curves are non symmetrical which puts the centroid off to the area centre instead of the dimensional centre

Any other ideas?


Hi G- the gumball appears at the bounding box center - you can run BoundingBox, and find the center of the resulting rectangle.
@graz - here’s a python that may help -
MarkBBCenter.py (754 Bytes)

To use the Python script use RunPythonScript, or a macro:

_-RunPythonScript "Full path to py file inside double-quotes"


Great idea, I’ll run BoundingBox and then CenterMark on that box then delete the box.

If any devs read this it’d be great to be able to set the centremark on that type of closed curve.

Thanks @pascal