Hello everyone,

Still a beginner I was wondering about a particular simulation that I have to do.

I have the alembic of a spacecraft that takes off and I have to make the reactors fire. I can't keep a constant fire (like a blue fire, small but very powerful ; without alterations or forces that are applied to it) that follows the animation.

Either the animation is too fast and the fire no longer follows either the shape of fire makes it unreal..

Any tips?

Thank you for your answers and sorry for the mistakes, my english is pretty bad

One way to approach this, if you want a steady flame is to simply simulate a single steady flame for the number of frames you need. Then export it as .bgeo or VDB sequence. Once you have a pre-simulated flame you can import it once, using the File node, and copy it to as many engine ports as you need. Parent them to the spaceship and you are good to go.

Another way is to enable the Track By Object option of the resize_container node. Choose the SOP path to your spaceship or engine port. For fast moving objects you may need more substeps on the PopSolver. Try increasing max to 3 to 9.

Thanks a lot for this advices ! I'll try this

Another quick question: How can I put my animated camera (imported in alembic archive) in the right axis?

Rewind, and create a new camera in the same exact location as the Alembic camera. Then make the Alembic camera the parent of the new camera. Look through the new camera and adjust the rotation offset +/-90 degrees XY or Z as needed.

You could try following up the Alembic camera with a Transform node to try and offset it. Not sure if that will work, though…

Hi !

I come back now on this project, others have required my attention…

Enivob your solution for the steady fire with pre-simulated flames works perfectly. But now I need to parent them with the spaceship and I don't know how to do this on the whole sequence.

Someone have a way? My object comes from Maya in alembic.


Thanks !

You can arbitrarily connect one transform to another via hscript commands.
Drop down a Transform node right after the mesh you want to align/parent. Then paste the above code into the XYZ fields. You will need to adjust the path to the source, which might be your “parent”. i.e. spaceship model.

It does not seem to work with this method…
My ship was animated in Maya so i don't know if Houdini have the right informations.. I can see center positions but nothing about translate, rotation or scale

My problem is surely an amateur thing. Maybe with an animation constraints or something like that?

EDIT: Center positions of my alembic give me translate animation as I suspected but my object turns on itself at the beginning. My fire doesn't follow the rotation of the spaceship. Any idea?

Anybody? Just want to add the rotation of my initial alembic from Maya to my fire pre-calculated in Houdini. Or another way to parenting this two elements..

I take this opportunity to ask another question: in my scene my groundplane catch some light of my fire. How can I keep just the light without the geometry of the ground? Light disappear with a matte_shading or shadow catcher..

I attach pictures for my two problems

Thanks !