I am not sure if this is a bug or a workflow issue. , in this system that I have I am getting a cool effect but its not the one that I want. Basically its particles along a path going to a find target when I Stoke it. some of the particles match up with the pflow and some just stop mid way and I have had to scale the velocity field massively.
I also wanted to say that I am really stoked about Stoke. Up resing particles has always been time consuming specially when you have to run it through pflow again , this would fit in nicely with many pipelines. Great job Thinkbox! find_target.max (332 KB)
It is As Designed.
The key to understanding Stoke is:
*In PFlow, particles have their own velocity and thus inertia - if you assign a Velocity on one frame, they will move in that direction forever unless affected by external factors (collisions, Forces, other Speed operators). The exception in PFlow is FumeFX Follow which dictates the exact velocity on each particle when set to 100% influence.
*In Stoke, particles do not have inertia. They FOLLOW velocities provided by external sources (other particles, space warps as velocity fields, FumeFX etc.). If the medium stops moving, the Stoke particles stop moving.
In your example, the PFlow particles move along the path and at some point you stop emitting PFlow particles. Thus, the velocity field becomes zero in the bottom part of the spline and all particles stop.
To create the look you want, I would suggest either continuing to emit particles, or adding a Spawn by travel to emit some secondary particles from PFlow that continue moving around after the main particles have passed… I tried with spawn every 12cm, 10% Spawnable, Inherit Speed 5%, Variation 50%, Divergence 180.0. It created a nice after-motion in the lower trail.
Remember that you are “painting velocities” with your PFlow particles, and the velocities are taken on each frame without regard of previous frames. You need a good “base painting” to get beautiful results from the Stoke particles following it…
That is great to hear! We imagined it would be useful for many people, but it is good to actually get some positive feedback!
Thanks for the explanation. So the velocity field can’t be zero at any point? I thought that if i synced the particle birth times for both pflow and stoke it would have a veocity to follow. It seems that some particles are getting left behind and therefore creating this extra trail effect. Is it something like there is not enough “res” in the velocity field?
The velocity can be 0 anywhere, then the Stoke particles will stop. Keep in mind the velocities are on a grid, so it depends on whether the voxel with a Stoke particle “sees” a velocity from the driving particles. Once you stop emitting, the PFlow particles move away and some particles might be left behind. Esp. given that the PFlow particles come from a point and the Stoke particles from a larger Torus. A lot of the Stoke particles never get so see a velocity in a voxel near them…
Ok thanks I willl keep that in mind I guess its always going to be a bit tricky when trying to form objects with particles. Is there a way of visualising the fields currently?
