Today I have noticed something that I overlooked when started learning blender.
I have this simple mesh:
I have tried to select all the outside perimeter and was surprised when just one side was selected (Same happens for the other 3 sides). So, I searched for the definition of Edge loop and it seems to be: All edges that are composed by vertices that have 4 edges connected to it. So something like this:
all these horizontal edges have vertices connected to 4 edges. So, they should be part of the same edge loop.
Coming back to the first picture I posted... why are these 4 edges selected if they don't have vertices with 4 edges connected to them? I see vertices connected to 3 edges int he middle and 2 edges at the extremes.
More over... if this edges are selected, why aren't then all the others at the perimeter selected too?
Sorry if this is a very convoluted question for such a basic topic, but I tend to overthink some concepts :).
Thanks in advance!
Martin will probably have more technical answer, but the selection stops basically because Blender doesn't know where to go. I picture it like something like this:
When there are no interruptions the loop selection go through, but as soon as you have a pole or the selection has to "make up its mind", it stops since it can't know where to go, so you have to select the other parts, like waiting for your input.
It's kinda how I picture when you select the outer perimeter edges, it reaches a point it doesn't know it has to turn. But again, that's how my mind sees the logic, Martin will have the proper explanation for sure.
Ummmm, yup correct, but... let me explain what I think should happen:
1. I try to select the top edge loop (like in the picture)
2. it starts selecting edges and gets to the extreme vertices. For example the one on the right. At this point there's no other way to go but down. So, at least for the next edge the direction is clear IMO.
So, from this, shouldn't it at least select one more edge? I mean, from the extreme vertex to the next one down. At this point you're right there are 2 ways that could be followed. (Down or left), if doing right side or (down or right) if doing left side.
Hi hhexdump ,
Don't worry about it, just Select and see what gets Selected.
What you are talking about are Boundary Edges (term from Mathematics, Topology). In Blender an Edge that connects to exactly 1 Face is a Boundary Edge. Selecting an Edge Loop from a Boundary Edge once gives the left result, ALT Selecting the same Edge again, Selects the whole Boundary as seen right::
But seriously, don't worry about it, just accept what happens when Selecting Edge Loops.
Here's the thing, you say it should do one thing, because you know that's what you want. Blender has no way of knowing if you just want the top edge or if you want the entire outer boundary or if you want just the one corner. So, they just go for the simplest path and then you can just shift+alt click the others to add to the selection. You can also select one edge in edge select mode and press shift+g->amount of faces. Since all of the boundary edges only have 1 face connected to them it will select only those edges.
***Edit*** WOW! Thanks Martin. I just reread your comment. I didn't know that if you Alt+Double click it would select the entire boundary edge.