How would you handle finding the interior area of a grid selection?

[Bdcoll]

Hey all,

So i have myself a little Blueprint (Grid_MASTER) that spawns a 6x6 grid of little Grid elements (These themselves are an actor blueprint (Grid_Element).

These Grid elements are stored in an array in Grid_MASTER and have both their Array Index and a X + Y Coordinate stored in them as if they were a 2d Array.

I’ve also built up a little drag and drop selector so I can drag over a bunch of grid elements and change their colour. The end idea is to be able to create a highlighted grid shape and turn it into a room.

My problem is I can’t for the life of me think of a way to get the outer edges of the selection. If it were always a simple rectangle by itself it would be easy, but these selections could be “L” shaped, or join onto other rooms.

How would you guys approach this problem?

[illspiritx]

Probably not the most optimal way to do it, but I’d probably spawn small-ish cube collision components beside each grid cell and check for overlaps. If it’s making rooms/buildings, I’d probably place the floors first on selected tiles, then add the collision comps outside the selection and see if they overlap a floor piece. Or maybe line traces down from tile centers ±grid size to check for floors. If no floors are hit or overlap (depending on method), it should usually be safe to assume the space is outside the building.