random generate objects along screen perimeter

I would like to generate specific game objects, bad guys if you will, in random locations along the perimeter of the screen, preferably outside the perimeter so we don’t see them spawn.

I would like to have these objects home in on a specific location like the center of the screen 0,0 coordinates.

I want to be able to randomly select from a pool of several objects to spawn and have the spawn frequency increase over time.

I’m new to lua and programming in general. I’ve been looking all over for examples of this and have not found much. I’m not sure where to begin.

Any help is appreciated. [import]uid: 20207 topic_id: 6284 reply_id: 306284[/import]