UMG Widget Clipping - How to diagnose?


Apologies in advance, I can’t send any code/screenshots of the “real” issue due to the nature of the project, but as I’m asking for guidance I’m hoping that I can get away with an explanation and a mockup picture.

We have a level which consists of a simple flat UMG interface. Within that interface we have a “widget” which is moveable, it can be dragged around by the user and that widget can be initially placed as rotated at a given angle (either 0, 90, 180, 360). For simplicity, let’s just say it’s a flat rectangle.

The problem is, it looks almost like a “clipping region” that matches the size of that widget (but NOT the rotation) moves around the screen as the widget is moved, but is not itself visible.

It can be seen when it masks the original widget if it overlaps it, such that it renders the underlying background colour. Almost like it’s punching a “do not render here” hole in that widget.

If you look at the picture below, the red rectangle is the widget and say (for example) we’re dragging it up. It looks like there’s something being created which matches its size (see the blue rectangle) which moves the same speed but in the unrotated direction, it’s not visible itself. Like a mask.

When/if they overlap (the lightly hatched area), the user sees the black background as if UMG has said “do not render here”.

So the questions are:

  1. What tools (and I mean utilities, breakpoints, settings, ini files etc etc) do I have to detect what is going on here?
  2. Is there some clipping/masking data/code for UMG somewhere I can put breakpoints on?
  3. If there is clipping/masking in UMG somewhere, can I turn it off or change the mode somehow?

I’m 99% sure we’re not explicitly creating anything behaving this way, it feels like a transform or rotation used to mask the widget isn’t being set to match our widget.

Sorry for the brevity, I know it’s a bit vague in places but I’m limited in what I can post. And sorry if it’s something obvious, UMG is new to me.

Thanks in advance!


Hello RayIon,

After taking a quick look at this issue it appears that this may be related to a known issue. I have provided a link to the public tracker. I hope that this information helps.

Link: Unreal Engine Issues and Bug Tracker (UE-4659)

Make it a great day

That looks highly likely, along with some of the related bugs (which we’re also encountering, sadly). ■■■■.

Any pointers on how to fix these bugs? Or timescales as to when it might be fixed? (Though aware of the lack of votes of course :frowning: )

I guess we’ll have to constrain our widgets/images etc…