set emission amount by surface speed?

[Saca]

hi,
can you tell me how to set emission amount by surface speed?

the scene is, some papers are flying, somes are stopped, somes are slow moving, somes are fast moving.
and they are emit particles like 'tinker bells'.

property_Test(velocity magnitude) is not work in this case, velMag=0 broken?
and one-zero switch is not match in this case.

thanks

[d4rk3lf]

Can't you simply use spawn - by travel distance?
The faster they are, the more distance they will travel, therefore, they will spawn more particles.

[Saca]

thanks.

the paper (emitter) is not particle system, that is mesh object animated manually.

thus, scatter particles into the paper objects (sticky setting),
the particles using as spawn-emitter, and check the parent-particle speed.

exactly, that's nice.
but can not i set emission amount by surface speed directly in tyflow?

[d4rk3lf]

Well you can probably use "property test" operator where you can test their velocity, and above certain speed you can spawn them in the next event with spawn operator.. but then again, spawn itself have "spawn by travel distance" already implemented, so why not using it? 
Maybe there is a more straight forward way then property test (and apart from just using spawn), but I can't remember right now. 

So, if you have several papers, manually animated, and you want to spawn some particles from them acording to their speed, here is how I would set the flow: 
- Birth  (at zero frame maybe 2000-5000 particles) 
- Position object (papers) 
- Object bind (papers... set it to "lock to surface", and don't forget to check verlet, so particles have their velocity moved forward) 
- Spawn (by travel distance... set distance as you like.. and don't forget to check inherit velocity in spawn, that is by default at 100% (so make it lower, or higher, according to your needs... 
.... now connect spawn to new event where you will have... 
Shape (pick any shape that you want) 

And in this new event, just place operators to your need.. if you want like magic dust, you will probably want some force operator with low gravity and turbulence... maybe collision for ground... etc...

[Saca]

spawn by travel distance worked well.
ObjectBind:verlet option is very important.

thanks!