[vfx] wind trail

[kgc00]

Why

According to the codecs card, I've implemented some wind trails for use when authoring scenes.

How

https://forum.unity.com/threads/vfx-wind-trails.1159775/

It works by having a parent volume which contains the actual visible objects but does not emit particles itself. Then, we have one prefab for the loop-de-loop wind trail and one for the straight wind trail. We can customize the rates, boundary size for the spawn volume, size, and speed on a per-prefab basis to match whatever setting the wind will be spawning in.

example