hy everyone;
i have a big problem that i cant setup pyro fx (fireball) in my object
in movement :cry: .
how can i do how can i do with this trail of fire and smoke that not dissapire.
also in render i cant have the alpha channel when object with pyro move .
plz what can i do?

So I'm actually doing this exact thing right now, and there are a few things you should try to make this work.

First make sure your fluid container(located in the pyro smoke object if you used the shelf tool) is starting in a location that lets it grab the fuel source on the first frame. Next make sure your resize_container is using a tracking object. This helps in making sure the default resize that gets laid down with the shelf tool doesn't lose your source if it moves outside of the original bounds of the fluid container.

Next on the fluid source you can add motion blur to your source in the scalar volumes tab. If your source geo is cached out make sure you add a timeblend node in before it gets converted into a volume, that way it has the proper attributes to create the subframe motionbluring.

The combination of those two things should help a bunch in getting a more stable sim out, but depending on how fast your source is moving you may have to substep your dopnet as well.

This peter quint tutorlal covers pretty much everything I said above, and will most likely fix most of your issues.
http://vimeo.com/38288672 [vimeo.com]

If it's still not working after trying all that, post your hip file!

Hi, I am also trying to make this work

I have my sphere run through a wall (so the sphere has rds solver) and I put velocity in it for it to go through the wall.

I have put and applied all those thing in my scene however it does not move, the animation of the pyro is only stay in one place which is the start point of the sphere.

I noticed that the tracking gets the reference to the sphere file that of course it does not move anywhere because I put the velocity not a starting path or so, so the sphere move when the rbd solver kicks in.

so now I have been trying and do not really know which of the sphere that I should put the reference then? because I put before rbd solver, it doesn't work (yes because it doesn't move yet by then)

so any help?

thank you

@mottchzee

What I would recommend doing is caching out your rbd simulation of the sphere breaking through the wall.

You most definitely need to have the pyro be tracking the post-simulated sphere, because like you said before it gets run through the solver its just a static object with initial velocities. The reason I recommend caching your sim is that if it is not cached every frame that the pyro needs to track the sphere, it will have to run that rbd sim first. If you cache the sim to disk (using a ropout or file node in conjunction with dopImport) houdini only has to look up point positions, and not run a full rbd sim.

If it's still not working after doing that feel free to throw a hip file up and i'll check it out for you.