Wish - extend/trim curve FENCE option


i am drawing a layout and need to change lotsof things extending curve trimming them etc. and i thought that if something like “fence” option as in Autocad it would be better, but as far as i know there is not an option for extend nor trim. Do someone knows a way?

thank you

what is fence? VIDEO

Better explanation here:

1 Like

Looks like a convenient addition, especially for curves that are not straight.

In this case, because they are straight, you could opt for the following (this should be less repetitive than having to extend each curve):

  • Split the curves with a vertical curve
  • Select the parts to extend (left of split curve)
  • Use Scale1D to extend them beyond the fence
  • Use Trim (or maybe CurveBoolean?) to trim the curves with the fence
  • Join the remaining curves.

This is actually does work to some degree, but appears to be buggy in its implementation. The problem with Extend is that you have to pick the curves near the end to extend or it doesn’t work. The main bug is it is possible to re-select the selected boundary curve as curve to be extended, which is wrong and needs to be fixed.

You can crossing window (right-left) select the curves to extend, as long as you get somewhere past the halfway point on the side to extend it works - but if you hit the boundary curve (or a curve already extended?) it fails.

A trick here is to use Lasso with crossing selection… Lasso does work as a polyline fence if you do not hold the mouse button down but just click points as if you were making a polyline. But it doesn’t seem to get everything unless its closed, so I just dragged it as usual.

See quick video for success and failure modes.

Oh, and I wonder if a separate ExtendCrvsToBoundary command would be useful, where one could preselect curves to extend and then the boundary, and the ends of the selected curves nearest the boundary would get extended to the boundary.



i wasn’t aware of that lasso can be used in extend thank you @Helvetosaur . Like “chain” is available for filletedge. and not seeing these options in command line does not help either. Why they are not in the command line?

if they are arcs then there should be a filter for shortest extension length to prevent the extend command processes the long way and result a circle, am i wrong?


That’s what I meant when I said

“and the ends of the selected curves nearest the boundary would get extended to the boundary.”


i should have read more carefully. :pensive:

Hi Blastered- SelBrush is also handy in this context. Keep to the end to extend, as Mitch points out.


thank you pascal,

why these options are not in the option lists of those commands?


Hi Blastered, the selection tools are just Rhino commands- they are available whenever it makes sense (or should be) to use them. I’m not sure if I am answering your question…


Hi Pascal,

I think Rhino should suggest what user may need to select, instead of knowing all selection commands and typing them there should be (in my opinion) those options.

i remember once chain select was an option of filletedge and can be easily turned on by pressing “C” then Space bar, but now user needs to type “chain” then press space/enter/RMB, kind of time consuming and not practical isn’t it? While creating this topic i thought something like “fence” (turns out selbrush and lasso are rhino equivalents) options could save time by just hitting the right key.

by the way splitting a surface/solid by selcrv makes sense to me but does not work.


This topic has taught me also something about selection commands. To make these more quick to access, it may be possible to assign a shortcut key to them in the Options dialog.
This can save you typing, and you will have the same shortcut across all commands.