This simple tutorial will teach you how to add good looking rain or snow to your level. You need to know how to create simple levels and how to add things and cogs to them. The snow or rain will cause minimum lag and framerate drop, due to the use of particles instead of sprites or animated sector surfaces. Just remember not to add too many ghosts.
Note: Be sure to download the files used in this tutorial before proceeding.
If you want to know more about the effect itself (the particles), open your level's .jkl or the master.tpl in JED\Jeddata with a Text editor and search for +snow or +rain. The values you find there are explained in other tutorials on Massassi, such as the template reference or the weapons templates, and you might want to check the jkspecs for explanation of the flags. If you want a sample level with snow, download Hoth Defense Station: it uses the same technique and almost the same particles...
Note: The falling distance of the two particles are set to 1.5 JKU, so make sure you have no enclosed rooms below within this range, or the effect will there be seen, too (look again at the picture). To adjust the range change the timer value of the template. You can also change the vel value (velocity), because the range is timer * vel, but this will probably destroy the rain or snow feeling...