Select objects laying on certain cplane


Is there any way possible how to select curves points etc. laying on certain cplane?

Lets say i need all these cross sections which are associated with named cplanes exported to separate files for example oriented on xy.

but first comes first there is prerequisite to somehow distinguish geometry according to what cplane they lay on.

any ideas? thanks :slight_smile:

Hello - a macro of _SelVolumeBox would maybe avoid needing a script for this:

SelVolumeBox Pause Pause Pause .01

Set your custom CPlane first, & make your pick points outside all the objects.

@ivan.galik see if this does anything good - (3.6 KB)

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

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


Thanks I have tried the script.

I get it that it should work the way you first pick some object which defines the plane and script should select all the objects on that plane?

It seems like it only selects objecst which are co-planar not all objects which lays on the plane. Lines are not selected because line doesnt define any plane.

Lines do lie in in a plane - well maybe not ‘a’ plane, rather an infinite number of them - so once you have a plane, one can test to see if a line is in it or not - both endpoints just have to be on the plane.

So, lines, while being theoretically planar curves, should not have a unique plane. However, it seems that in Rhino, if they are parallel to only one of the principal planes, they do get assigned that plane. That means that lines parallel to the X, Y and Z axes do not have a plane, but a diagonal line that lies on the world XY plane for example will get assigned that as a plane.

So, to make a script reliable, one maybe has to exclude lines as possible plane source objects - the one you choose first to compare others to - but, a simple test can determine if in fact they do lie in a chosen plane afterward.