Cube outer edges edge loops selection

Hello, I am interesting why Cube, and cube created from Plane on the outer edges have not loops selection like all other objects.


Next time, use a image to illustrate or at least prepare the scene to get to the point quickly. It’s not necessary to make pretty images or videos to ask a question, just informative ones.

Anyway, the reason is because cylinders, cubes, holes, plane edges etc. aren’t edge loops.

Strict definition for edge loop is that the edges go over junctions with 4 edges (1. grid) and stops when there is more or less edges. That means it stops at poles, which are vertices with 3, 5, or more than 5 edges connected to them (3. grid). Or in other words, other than 4. Everything else is just built-in functionality for convenience to be able to select boundary edges on holes (2. grid) or other edge flows that follow some rule base.

All corners in a cube are poles. So are the ones with a cylinder that is capped with an n-gon but Blender still treats them differently.

Thanks for reply.

I understand now. But beginners, like me may be confused with some convenience inconsistency, on almost all objects outer edges edge loop selection works, but on basic objects like Plane and Cube not. And they begin to wonder what they are doing wrong. I know I can select it in other ways :slight_smile:

You’re welcome.

I forgot to mention, latest Blender (2.71) has another convenience functionality included to allow selecting boundary loop around a plane. You can do the selection by selecting the border edges with alt+RMB and then doing the same selection again. Doesn’t work for cube though.

You are right, in 2.71 works as you wrote. In my opinion this deepens the selecting inconsistency. It is only theorizing - if you have joined empty circle and plane and want to select loop: On plane second ALT+RMB select loop - if have all selected and click ALT+RMB on another edge it deselect other. On Circle first ALT+RMB select loop, when click ALT+RMB on another selected edge, it only change active edge, not deselect any other. Also if I have e.g. two joined Circles I can on first Circle ALT+RMB and on second Circle press SHIFT+ALT+RMB then I have all selected. On two joined Planes it is impossible.

Yea, it’s not a groundbreaking addition. Not sure if I even use it that much. Select menu -> select boundary loop (or same from edges menu, ctrl+E) works with more complex selections and isin’t limited to outside boundaries.