Trying to dive in to Blender again and really struggling to understand some of the basic selection logic.

Specifically border selecting edges in Edit Mode.

Border Selecting 2 Verts

When dragging out the marquee I've intersected 4 edges and completely encapsulated 1 edge.

In most programs this would result in 5 selected edges.

But here you can see only 1 edge is selected.

So you would think this meant that Border Select only selects edges when all their verts are completely surrounded by the selection border.

But here comes the twist!

Border Selecting 1 Vert

Here you see only 1 vert is surrounded, yet the result is 3 selected edges!

This seems both inconsistent and counter-intuitive.

Is this the intended selection behavior for this tool? If so, why is this desirable? What's the advantage to this approach? I'm trying to understand the logic so using it isn't so frustrating.

Otherwise, is there another mode for Border Select that makes it behave more like you'd expect it to?


  • $\begingroup$ It looks like Border select is "smart" and will do this: 1. check if the selection fully encloses any edges, verts, etc (depending on what mode you're in) a. If there are any fully enclosed items, select those ones. b. if there are no fully enclosed items, select all intersecting items. Lasso selection also follows these rules. You might want to play with the circle selection tool (press c) which will always select by intersection. $\endgroup$
    – Tavi Kohn
    Commented Jul 6, 2018 at 18:15
  • $\begingroup$ Ah, nice about circle select. Thanks. It would be really great though if instead of limiting certain selection behaviors to certain selection tools, all selection tools had common modes: an intersection mode (crossing), fully enclosed mode (window) and "smart" mode that you could toggle between so all your tools would work the way you wanted them too. Oh well, thanks for the reply! $\endgroup$
    – andyV
    Commented Jul 6, 2018 at 21:46

1 Answer 1


Interesting question, never gave it much though, but now that you mention I did some investigation and came to the conclusion that I find it a smart and consistent system even if apparently unexpected at first.

If you border select only one corner, imagining you are in vertex selection mode, you are technically selecting one vertex only; so Blender automatically extends the selection to all the concurrent edges.

enter image description here

If you fully encapsulate an arbitrary number of edge then Blender will assume you want to select them and ignore the "vertex-extension" mode.

enter image description here

If no vertex is selected and no edge is fully encaspulated then "crossing-mode" is used instead, and any touched edge is selected regardless of being fully inside the border or not.

enter image description here

  • $\begingroup$ Hi! Thanks for the answer! I appreciate your opinion, but for me having it switch between two different selection behaviors is kind of confusing instead of consistent. I'd actually much prefer explicit window/crossing modes so that way I can reliably expect one behavior or the other every time. Oh well, at least now I know. Thank you! $\endgroup$
    – andyV
    Commented Jul 6, 2018 at 21:17
  • $\begingroup$ p.s. Your blue selection highlights look pretty slick :) $\endgroup$
    – andyV
    Commented Jul 6, 2018 at 21:31
  • $\begingroup$ Behavior is hardcoded has far as I can tell, you can't change it, at least not without changing code and recompiling Blender yourself. The apparent pre-selection highlight is actually an undesired side effect of my custom keymap, though it is mostly harmless. $\endgroup$ Commented Jul 6, 2018 at 22:07
  • $\begingroup$ Thank you very much for that explanation it seems logical. But still in my case the behaviour is neither mode x nor mode y. I fully enclose a lot of faces - still the top triangle that is not fully enclosed gets selected. GIF here: v22018086713571297.hotsrv.de/owncloud/index.php/s/… $\endgroup$ Commented Jun 4, 2019 at 9:38
  • $\begingroup$ I can't access your link. Anyway if this is about your previous question it is probably best addressed in your own post for context. Could you please edit your original question and use the builtin tools there to post your images? $\endgroup$ Commented Jun 4, 2019 at 9:48

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