making those 'splash' rings

Please help!

I realise the info must be available somewhere, but I've been looking for hours and can't find it.

I want to make one of those effects where entering & walking around in water causes concentric rings to form around the object/avatar. I've made the texture (having assumed I'll need it!) but can't figure out to make it happen.

Should I be using a prim or a particle?

How will SL know where to put it? Found llDetectedPos, but am flummoxed as to how you apply the result.

Also - what about poisitioning? I haven't yet succeeded in making particles that appear on one plane, in one place, only. I tried pattern-drop with no velocity, but nothing appeared .... or, if using a prim, how do you make sure it always rezzes exactly on a level with the top of the water?

I'm really hoping someone can point me to the definitive tutorial on all of this: if not, maybe you'd be kind enough to help me out?

Thank you!
Cherry

I'm honestly not sure how the splashable water works, but my best guess is:

1--Scripted prim detects collision (collision_start on a vol detect prim probably)
2--Script acquires position of colliding object/avatar (not sure exactly how...llSensor would work I know...but there's gotta be a better way...I've just never even looked)
3--Rezz a prim in the location of the collider's position (llRezObject)
4--Emit particle or animated texture that looks like ripple (probably an animated texture)? (the rezzed object would have something like an anim_smooth script (it's in your library) in it with a semi-transparent ripple texture)