Need particles going up and down, do I need 2 ?

I have some particles (smoke), at the bottom of the screen it needs to travel up and at the top of the screen it needs to travel down.

I have it working but the only way I could get it working was too create 2 particles types and change the weight.

Just wondering if there is a better way, so I can get rid of some code ?

Dave [import]uid: 117617 topic_id: 28621 reply_id: 328621[/import]