Map GUI cutout

For all the minimap examples on here I can't find one that does quite what I want. I can't get it happening via the blend modes example either.

My primary focus is just to overlap a map in the corner of the screen.

The map is a separate file that looks like a map (only green and a bit transparent so it looks like a scan, but that's probably irrelevant) The aim is not to show the whole map but just show further away, so I just want to be able to take a large graphic (the map) and only show a circular cutout of it and have the rest transparent. This minimap is going to turn and move as the player does so a the static map examples are not enough.

TLDR; How do you only show a circular piece of a graphic and hide all the rest? (Is it possible? All the minimap examples I find all seem to be static)

Basically I'm looking for something like the "destination in" effect in the blend mode example except I need it to be transparent instead of black. Maybe I should be asking if there's some way to turn the black transparent?

Create a separate layer for your map, and set 'Force own texture' to 'yes'. Add your circle to this layer and set the 'Blend mode' to 'Destination In'.

Now anything on this layer will appear inside the circle, with anything outside completely transparent.

Aha! Exactly what I was looking for, thankyou Thehen.