I am not sure if I understand correctly, but how are you drawing your tiles at the moment? In the tile engine I wrote, I used dynamics sprites, which you can draw with a transparency value. I wouldn't recommend to use anything else to be honest, objects are limited and slow as are characters in that amount.
I'm making tiles in MSPaint. This is the way I make my backgrounds:
- I make a grid which can be filled with tiles (No gridlines visible after placing all tiles. Mostly I use 20x20)
- I make some basic tiles which I'm going to use (walls, floors, standart objects.)
- I save the grid as another file and colourize it in a code that indicates wether I want wall, floor or special tiles there.
- I place the basic tiles.
- I copy this picture and add the grid on it again.
- I add detail to the grid-containging copy.
- I paste the copy on the original background, making the gridlines invisible using MSPaints selection transperany (so they'll dissappear.)
In short, I don't use an engine for my tiles, but simply a paint program.
The problem is that I wanted to create regions on places where the player walks beneath a roof/wall (seen from the players view). I want the roof/walls to dissappear or become transperant when the player stands on that region.