round((3+dim+dim)-((y+x)*0.03125),1)
Where dim is the dimensions of the display (It's a square, so dim is the same for both sides), y is the isometric y co-ordinate of the object in pixels, and x is the isometric x coordinate of the object in pixels (Hence the division by 32).
I'm trying to set it up so that objects closer to the 'bottom' of the diamond overlay objects further away from it, but it don't work. There's a host of interesting errors, and I'm not sure what formula I should use. Any suggestions?