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I have a large scene with many objects but want to cut out only a part of it before sending it to the client. I drew a 3D bounding box defining the region of interest 3D selection box, and I want to:

  • Delete all geometry outside the box or
  • Select all geometry inside the box

Secondary information

I tried boolean intersection but couldn't get it to work. Maybe I'm doing something wrong.

Related: Boolean modifier on groups - can't select 2nd object - is this possible?

In my specific case, I have no face geometry in the scene, only vertices and edges (a.k.a. polylines or curves). Of course the box used for selection has faces.

PS: I prefer manual solutions for such a basic task but python would be ok.

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    $\begingroup$ I'd say Boolean modifier won't work in this case as you have no faces - "The Boolean modifier doesn’t work on edges without faces.". A kind of lazy solution could be used if all the objects were joined; then you could select/delete unwanted using Box Select from the top view. If without joining I think it may be done only with script. $\endgroup$ – Mr Zak Nov 4 '15 at 0:48
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Beside what Mr Zak said, the only (crappy) way is to use the "bisect" tool in edit mode on each object to be "cut", using the box as reference, of course cutting in ortographic front/left/top mode. That cuts yor geometry (even without faces), adding new vertices along the cut edges, so that, later you can delete unwanted geometry outside the reference box...

The bisect tool is crappy, too, it has no way to keep straight, and is not affected by snapping, too. Again, if your cuts are not "perfect", your only hope is to use the snap tools after the "bisection", aligning the new vertices resulting near the box limits, to align them to the box vertices...

If not clear, I can make some reference image...

[edit] here you have the whol (crappy) sequence:

I started from a simple test setup but similar to your case, I hope:

enter image description here

seen from the side

enter image description here

so if you select the grouped green shape (this is only 1 mesh I just added a group to make it green like yours and also visually show it better) in edit mode, acting from the basic side view (ie: not in perspective mode, but ortographic, since you have to cut straight lines "by hand"):

enter image description here

You can select all the mesh (A key) and use the mesh>bisect tool.

enter image description here

Once you select it, you have to drag a straight line (you can start it from anywhere, I chose the intersection of green and orange lines, of course).

enter image description here

in the above image I angled it a bit for you to see it better, but you have to keep it straight, and drag it until it "cuts" also the bottom green/orange cross:

enter image description here

as soon as you release the left mouse button (LMB) the cut is set, and your mesh (also if has no faces) is cut, and new vertices made along the cut on all edges, as you see below, from an angled view.

enter image description here

of course you could be not as much precise cutting by hand, but you could always use now the snap tool set as you see below

enter image description here

then align those vertices (all together or even one by one) to your "limits box" (the orange circle hints that the selected vertices are aligned to the enclosed vertex of the "limits box"). I dragged them on the X axis in the example, and pressed the CTRL key to "snap" them until the orange circle confirms the snapping:

enter image description here

after doing this for all edges needed, you just need to delete "outer" vertices:

enter image description here

and you get something similar to what you needed, I hope:

enter image description here

...phew! :) what a crappy tool, I know...

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  • $\begingroup$ tks! will try. some reference images in your answer would be helpful. $\endgroup$ – rfabbri Nov 4 '15 at 9:01
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    $\begingroup$ ok, I added the best that I could, trying to keep it simple enough. $\endgroup$ – m.ardito Nov 4 '15 at 9:36

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