Game art-transparencies, particle EFX

hello, I’m trying to export explosions. lasers, lightning, and projectile vomit to my developer. (this is a Zombie game) I was the explosions to have glow EFX, so that the the alpha goes from 100% to 0%, but I can’t seem to export a PNG or TARGA that does that–it always seems to have a hard edge. is there some setting in PS (using CS3) that I need to use? is there some code in Corona that my programmer can use to chroma key out some colors to make it transparent? thanks [import]uid: 131481 topic_id: 26859 reply_id: 326859[/import]