Hi all. I'm trying to use the Houdini Niagara rop to bring an RBD simulation to Unreal and struggling in transferring the correct orientation for the pieces. Did anyone manage to achieve this?
I managed to create the correct orient attribute in Houdini, but how do I feed it to Niagara? What module should use this attribute? I tried “orient mesh to vector” with overriding the quaternion, but it gives the wrong orientation whatever I do.

edit - I found a solution - I had to generate a fake N from orient inside Houdini and export both orient and N, then I used this normal as Look at the direction in “orient mesh to vector” module + orient as quaternion override + N as reference axis vector + 1 override incoming orientation. This feels like an overly complex answer to a simple rotation question.

But I have new questions:
1 - Niagara side - When I try to convert emitter to GPU sim, I get an “invalid type for index in NiagaraEmitterInstance.ush”. Is it even possible to use GPU?
2 - Houdini side - After the first frame I have a weird position offset on each piece. I think it could be some pivot offset, but why it's only starting on frame 2? I mean It looks ok in sim right after RBD but if I delete geometry and instance exported pieces on rbd points, this offset appears.

Hi There

I am trying to create a looping particle animation and there seems to be a weird delay in the beginning of animation. I have reduced my data to 1 point and 10 frames and created a super simple position sampler, but the problem still presists.
In Particle Update my ‘Test Script’ just reads the position value of the particle 1 at frame 1 (the position is 0,0,0 here) and passes it on to the Houdini particle position parameter. But I have to go to approx. 0.03 on the timeline before the particle shows up.

WHAT am I not understanding here?!?

Cheers
Jacob

Could we please have the Unreal 25.4 compile? I tried to get into this and 25.4 is the only one Epic is giving me but the tools are compiled for 25.3. Thanks!

axess21
edit - I found a solution - I had to generate a fake N from orient inside Houdini and export both orient and N, then I used this normal as Look at the direction in “orient mesh to vector” module + orient as quaternion override + N as reference axis vector + 1 override incoming orientation. This feels like an overly complex answer to a simple rotation question.

I found a simple solution:
In “Orient Mesh to Vector”
1. Apply @up to ‘Look at Direction’
2. Apply @N to ‘Side Axis Direction’

Where I can find the plugin build for Unreal 4.26? . I can't find it in the GitHub.

Thanks

Hey,

awesome job with the NiagaraROP!

And a question. Can we use GPU simulations in Niagara with this setup? Currently, I'm receiving an error - Invalid Simulation.

/Engine/Generated/NiagaraEmitterInstance.ush(2234,18-152): Err0r X3120: invalid type for index - index must be a scalar, or a vector with the correct number of dimensions HoudiniNiagaraBasic, Particle GPU Compute Script,
/Engine/Generated/NiagaraEmitterInstance.ush(1752,2-29): warning X3206: implicit truncation of vector type HoudiniNiagaraBasic, Particle GPU Compute Script,

Thanks

Could we please have the Unreal 4.26 compile?

Any update for 4.26 is appreciated. It's been released for quite a while now and the Git repo hasn't been updated for a couple of months. Epic seems to have removed the plugin in the Unreal Engine repo likely because of compatibility reasons but it is problematic for projects depending on this plugin.

+1 for houdini niagara update for unreal 4.26!

Hi!

Any updates on 4.26?

I wander if there's a Niagara to Houdini interface in the future, so I can drive houdini simulation based on existing niagara particle then have it baked out?

getting this error when trying to write an hbjson file from the fluid_splat_walkthrough hipfile, you have to dig down into the hda to get the warning as it is not being promoted to the top level.

Is this plugin ready for UE5?

Any timeframe until this is good to go for the UE5 Early Access?

Has anyone managed to get it running / compiled in 4.26.2 so far?
Compiling does not work with the latest build in 4.26.2

Here are binaries for 4.26 and 4.27.

Updates to github coming shortly.
Github Updated Releases section

When I try to add forces to the cached simulation as is sown in some of the demonstrations each loop gets more and more distorted and the particles begin to jitter around. I am using the default Houdini Basic picking my Point Cache and then putting a noise, everything looks and works fine until I use a noise to add a little variation. I have also noticed that each loop doubles the number of points. Is there something more I should be doing? What is the correct setup to have?

UPDATE FIXED
It's worth mentioning that if a sim needs to loop they should be killed before the end of the exported cache's last frame or pad the loop beyond the lifespan. I think when Niagara injects more particles and looses track of ID's.

I can't use hbjson in Unreal Engine 4.27.0. I have successfully install Houdini Hiagara plugin for this version but Unreal Engine can't import that extension.

Has anyone been experiencing jitter in particle position on playback after some loops. It looks great for about 3 solo plays then it jitters and returns to looking fine again.

I am going to ask a silly question. Can these FX be done in Realtime? All the videos I have seen are in Game. Can you do the same thing but just in realtime?

Thanks
Alex