Line Trace by Channel not ignoring Actors to Ignore


so I got my Line Trace by Channel setup. It works perfectly but recently I bumped into a problem.

I need it Ignore building which I place depending on where it hits while I place it.

Right now I tried adding it to Actors to Ignore but it just isn’t ignoring actor. When I remove collision it does exactly what I want so it has to collide with itself and create a new point.

Here is a video to what I mean. first time is with Collision enabled. second one when it’s disabled. After it’s placed collision get’s enabled anyway but my problem is this real time placement.

[Video Link][1]

And picture of Line Trace itself

I seriously run out of ideas at this point.
Any help is welcome!

I am having same problem. I asked same question in a separate post. Haven’t heard anything back so far. Kind of disappointing.

Did you manage to figure it out?

Hi all,

I haven’t been able to reproduce this issue with LineTraceByChannel node. Would either of you be able to create a small test map with which you can recreate this problem, and uploading it somewhere I can get it? Thanks!


We haven’t heard back from you about this issue in a while, so I am marking this post as resolved for tracking purposes. Please feel free to reopen post when you have more details or a test map for us to look at. Thanks!

problem is still occurring, line trace is still “hitting” actor that I ordered to ignore… =/

Hi Filipe,

Can you provide a small test project that displays this problem? We have still been unable to reproduce issue here. If you can, up a project and upload it somewhere such as Dropbox or Google Drive, and get me download link. We can take a look from there. Thanks!


Ok, it is simple: I have a fog BP, same FOG one from blueprint example, and butterfly BP from same blueprints example.

I just want butterflies to ignore fog, because they are landing on it, using “get all actors of class” and hooking it to line trace of butteflies Blueprint does no effect.

PS: I´m using line trace for object, static ones, but fog I still want to ignore it, hehe

Thank you so much for trying to help!

BP_FogSheet? That doesn’t have any collision, so line trace couldn’t possibly detect it. Can you put this into a small project and let me see this in action? Or give me specific steps to follow to reproduce this way you did in Blueprints project?

I’m having the same issue with Unreal 5.4.1 in C++. I add an actor to the IgnoredActors array but it always ends up in my hit results. I also tried ignoring all of the children actors and components with no luck. My current solution is just to check in my loop below this, (omitted for brevity), if the actor is the actor I want to ignore and continue the loop. Does anyone have any idea how to actually ignore actors using LineTraceMultiByChannel or LineTraceSingleByChannel?

FCollisionQueryParams Params;
GetWorld()->LineTraceMultiByChannel(HitResults, TraceStart, TraceEnd, ECC_Interaction, Params);