Brush-spawned LIGH moves in the direction of gravity.  Vertical gravity points it down, radial gravity points it to the center, and if turn the gravity off; LIGH points in random directions.  TESC-spawned LIGH points in random directions regardless of which gravity mode is on or wheather any is on.  But you can manipulate which direction the LIGH will only point to by drawing DMND, or some other element that LIGH can't pass through or destroy, around the TESC except in the spot to where you want the LIGH to point.

tmp decides the direction of a ligh particle