Strands Question

[Adam Sale]

Hey folks, Its been a while since I've used strands, and I recently came across an issue that I can't remember how to fix. Searching archives yields no useful results, as I'm not sure how to frame my query. 

If I emit Strands from particles ( like rain streaks), and then spawning particles based on collisions with say a grid, the spawned particles inherit the strands, but they have this behavior where the strands are actually ahead of the actual particle from which they are supposed to trail. In the create Strands Dialogue, there is a Reverse Strand direction option, but this doesn't do it. 

Its easiest to see this on frames 15 and 16 of the dropbox attach. 

Heres a link to a scene so you can see what I mean.. I feel like this is one of those duh moments... 

https://www.dropbox.com/sh/z8p4v5kkh24fqhg/hOZ9aew6n9

Thanks for any thoughts.. 

Adam

[Thomas Volkmann]

Unfortunately the scene crashes at startup... at least on my machine :/

 

/Thomas

 

Adam Sale <adam...@gmail.com> hat am 22. Oktober 2012 um 05:35 geschrieben:

[Adam Sale]

Dang.. forgot that I had built it in a 2014 Beta.. 

Here is a link with a similar simple setup for 2012

https://www.dropbox.com/sh/z8p4v5kkh24fqhg/PlWaklwcbU/Raintest2012.scn

Frame 27 is the first instance of this extra tail on the newly spawned blue particles.. 

Just not remembering how to fix this one.. 

Thanks for any help.. 

Adam

[Ben Beckett]

Hi Adam

 

In the create Strand node, It might fix your problem if you tick on reverse strand direction.

 

Thanks

Ben

[Adam Sale]

I've tried it with both options, still the same behavior for me when I use it with  spawn on collision

[Daniel Brassard]

Maybe delay set data node need to go in there somewhere.

Dan

[Adam Sale]

Either way, this is something that should just work with the provided tasks. 

[Petr Zloty]

Hi,
There is an easy solution, look at the attached image. Just multiply
the strand length of splash particles by their age and then add small
value to prevent any errors.

It's because the trail generation compound remembers all of the
previous positions of the rain drop particle, and it doesn't empty
that list after spawn on collision event. So the strand is not ahead
but it's follow the original strand.


I bypass this problem recently with a little different solution. I
created the splash particles on different pointcloud, it works too.

Cheers

2012/10/24 Adam Sale <adam...@gmail.com>:

[Adam Sale]

that makes sense Petr.. 

I will check out your fix.. 

Thanks Man

Adam