Half-tile autotile example

Set up tiles like this: (inside corners to the right)
┌───  ────  ───┐
│              │     ┌  ┐

│              │     └  ┘
│              │

│              │
└───  ────  ───┘

x = 1
y = 1

//check left/right
if(left is open) x = 0
else if(right is open) x = 2

//check up/down
if(up is open) y = 0
else if(down is open) y = 2

//special case for inside corners
if (x == 1 && y == 1){
    if(top left is open){x = 4; y = 1}
    else if(top right is open){x = 3; y = 1}
    else if(bottom left is open){x = 4; y = 0}
    else if(bottom right is open){x = 3; y = 0}
}

use the tile at position x,y