Houdini Niagara Updates

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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.
Edited by axess21 - Nov. 6, 2020 05:27:22
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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

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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!
- “spooky action at a distance”. Albert Einstein
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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’
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Where I can find the plugin build for Unreal 4.26? . I can't find it in the GitHub.

Thanks
Edited by Josich - Dec. 10, 2020 05:04:13
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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
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Could we please have the Unreal 4.26 compile?
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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.
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+1 for houdini niagara update for unreal 4.26!
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Hi!

Any updates on 4.26?
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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?
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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.
Edited by sidenimjay - March 13, 2021 16:19:46

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niagraRop2_18.5.508_ERROR2.PNG (140.5 KB)

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Is this plugin ready for UE5?
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Any timeframe until this is good to go for the UE5 Early Access?
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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
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Here are binaries for 4.26 and 4.27.

Updates to github coming shortly.

Github Updated Releases section
Edited by Bob_Cober - Aug. 25, 2021 23:05:21

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HoudiniNiagara426.zip (54.6 MB)
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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.
Edited by Noboru_Garcia - Aug. 31, 2021 17:08:18
- “spooky action at a distance”. Albert Einstein
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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.
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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.
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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
As always thank you!

Alex
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