As a part of Japanese localization project, I made some good enhancements on impact effects:
http://www.hard-light.net/forums/index.php?topic=65667.40Sample Movie:
http://www.youtube.com/watch?v=qH-ZQd6vwzIIt is currently not yet marged to SCP, but it is nice to marge it to SCP. However, I made those enhancements in dirty way: I hard coded it without ability to control by tbl file. And yes, it should be able to be controlled by tbl file when you marge it to SCP. Just like:
$Impact Explosion: filename
$Impact Explosion Radius: #.#
$Impact Explosion Lifetime: #.# ;; in seconds
$Impact Explosion Flash: filename
$Impact Explosion Flash Radius: #.#
$Impact Explosion Flash Lifetime: #.# ;; in seconds
$Hull Impact Explosion: filename
$Hull Impact Explosion Radius: #.#
$Hull Impact Explosion Life: #.# ;; in seconds
$Hull Impact Explosion Flash: filename
$Hull Impact Explosion Flash Radius: #.#
$Hull Impact Explosion Flash Lifetime: #.#
"$Impact Explosion Lifetime": Optional. I gave bomb explosions long lifetime in my version and it looked good. So lets have this so that you can have long lifetime for explosion lifetime.
"$Impact Explosion Flash/Radius/Lifetime": Optional. In my version, it is hard coded but already look good. So it is good to show flash with hard coded default params when those params are missing. And you should expressly set "none" for "$Impact Explosion Flash" to disable flash.
"$Hull ***": Optional. If hull impact explosion params are missing, same effects are used both for shield impact and hull impact.
So required params are "$Impact Explosion:" and "$Impact Explosion Radius:" only, and it should work fine with all other optional params missing. But you can control details of effects by having optional params.