Hello to all!
I have a big problem on unreal engine : I can’t insert “Edge loops” after an operation with booleans. In other words, I’m trying to subtract two shapes, and then put an edge loop on the output shape, but the editor won’t let me do it. Does anyone have a solution to this problem?
Thanks!
Can you show a simple example of it?
Of course !!
First, i make my boolean :
Then, i try to make my edge loop, but it seems to be an error at the mesh corner :
If i try to make a vertical edge loop, no problem :
I see what you’re saying 
It looks like the same problem you get in Blender. You have to make edge loops early, because as the geo gets subdivided, the algorithm can’t find routes across the faces.
In Blender, the cube would be made of quads and it wouldn’t be a problem so early.
Not a very exiting answer, I’m afraid.
Okay, thanks for your answer !! 
It is because of a particular arrangement of polygons, basically. I could show you a video about how to avoid the problem in Blender, but that program uses quads, not tris, so it’s not really applicable. Even though it’s the same problem.
as @ClockworkOcean said, the boolean operation resulted in a topology that won’t allow for the edge loop to find a path. There are a couple options you could do to resolve this. The first option would be to control the topology from the begining by using edge loops in combination with extrude type operations so that your topology maintains quad polygroups.
The second option would be to use edge insert to split the front face into two quad polygroups.
You can then use insert loop to add edges where needed. Also it’s a good idea to switch the loop insert to “retopolgize” instead of plane cut it can really help keep the triangles clean.
Cheers,
R
