Rotating an overlay on a diagonal surface

[Pocket]

I tried placing an overlay onto a diagonal wall, and it wound up being upside-down. What the crap am I supposed to do to get it rotated back around the right way? I just can't wrap my head around the logistics of it. I tried rotating 90 degrees in two dimensions at once, but I wound up with the overlay either bizarrely stretched-out or at an odd angle.

 

[Idolon]

You have to go into the overlay's properties and edit the Start/End U/V properties. I think flipping the Start/End U and Start/End V properties should do a 180 degree rotation, but don't quote me on that.

 

[A Boojum Snark]

Sometimes I've done an overlay "transfer" when I need to rotate them in a way that won't behave, by placing the overlay onto a "normal" brush that will let me do the adjustment I need and then changing the face the overlay is applied to. Sorry I can't be more detailed without knowing the situation... and it has been awhile since I needed to do that.

 

[Pocket]

You have to go into the overlay's properties and edit the Start/End U/V properties. I think flipping the Start/End U and Start/End V properties should do a 180 degree rotation, but don't quote me on that.

Ah yes. I should have remembered that from back when I needed to place an overlay that was flipped. Swapping just one pair flips it; swapping both fake-rotates it 180 degrees by flipping it both ways.

Though I'm still curious if there's a correct method if I'd needed to rotate it 90 degrees.