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Houdini to Unreal - Vertex Animation Textures

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Hi,


I am trying to export a fluid sim from Houdini 16 using the new vertex animation textures node. I am having a few problems hooking up the material in Unreal. I have copied and pasted the Fluid UE4 code but have found that there are no notes on how to hook it up and get it working.


Does anyone know how to do this? or is there a sample scene or tutorial on setting up the Unreal materials?

I have attached hip and export files plus a screen grab from Unreal.


Thanks
Graham

Capture.JPG

flip.hip

flip_col.exr

flip_mesh.fbx

flip_norm.exr

flip_pos.exr

Edited by gramx

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Hey Graham, and anyone else trying to do this

I just put out a video with a little explanation of the gotchas of the process as well as the project that I showed at GDC with source files and an updated HDA (which should be going into the build anyday now)

A lot of people have been asking for more info on this, so hopefully this clarifies it a bit

 

 

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Hi Luiz,

I have been looking at the hip files and it seems that you have a newer version of the Vertex Animation Textures Asset. I get an error saying incomplete asset definition. Are you able to send over the latest asset or will it be available in the next Daily Houdini build. I am running 16.0.542

Thanks

Graham

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Guest VegaBeyond

Hi,

I'm using the newest vertex animation texture tool downloaded from github, but when I render, it just don't export the fbx mesh. So I have only the pos and norm exr... I'm using version 16.0.633. Any idea of how this happen? Thanks!

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Guest VegaBeyond
On 8/1/2017 at 8:17 PM, mestela said:

You're not using apprentice but any chance? Fbx export is disabled in apprentice. 

Oh maybe that's true... I'm in school and we maybe got education license for class T^T but it worked when some professional guy come for a workshop

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Just to toss this out there.    Earlier I was doing a export and found that the soft export (Beta from github) was overwriting my UV set.  When I dove in, the switch statement had the following warning.  


Warning 
Bad node reference: "../divide1" in parameter /out/vertex_animation_textures_beta1/soft_obj/STATIC_MESH/switch1/input.   which was causing it to always use the first input, which was a uv unwrap.  

After bypassing the switch everything exported as expected.  

Also, it appears to skip exporting the vertex alpha. 

Cheers 

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Hey guys, I just tried this witchcraft and its bloody awesome!!!

One problem though, When I apply my textures to the fbx in the demo unreal project, all works fine.

But.. when I use the fbx I export from houdini, it seems broken. I did check the "full precision uv thing.

brokenFBX.jpg.4ddf654a7331d9d8d491b12b9bbc1f54.jpg.

The vertex animation textures node in the demo project didn't want to export anything, so i used the one that ships with houdini.

I am using indie so i suspect that is why the included hda didn't want to work.

Anny suggestions?

Thanks

Gerbrand

 

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So my next problem is more about me not knowing unreal.

I created an actor from the vertex animated fbx, and spawn it into my game on a event.

The problem is that it seems to play on a loop, so it will just play from wherever it is looping as it spawns.

How would I force it to play from the start of my anim as it spawns into the world?

Thanks guys

Gerbrand

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There are a few ways to handle that.   For particle system stuff I usually add a dynamic parameter node in the material and control it in the particle system.  To get it to play via blueprints in a controlled fashion, instead of using time in the material, use a scalar value and control that using a timeline in the blueprint.  There are probably other ways but I think that should give you decent control.  

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Hey Neil. Thanks for the reply!

I think I did what you suggested, but the playback was jittery.

What I did was create a parameter node and plugged it into where the time node goes in the master material.

I don't know if there is a difference between a parameter, and a dynamic parameter as you suggested, but that's what i did.

The timeline in the blueprint was set to run from value 0 to 99, as I had 100 frames in my explosion.

I will try again, but if you can think of a reason why it would be jittery, please let me know.

If you have done this, and don't mind sharing a screenshot of your PB nodes and material nodes, it could maybe help me to double check what to do.

Thanks again

Gerbrand

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Hey guys, I'm having some issues using the vertex animation exporter - with RBD mode, it wont produce a FBX and so I have to manually export that which isn't an issue just odd and then with the shader correctly built in unreal I still get a horrible result?

 

ALSO has anybody tried to export cloth/soft body method? as for me after following examples and tutorials I only export a useful normal and FBX and the position map / vertex displacement part always comes out completely empty?

 

Attatched both my hip files also :)

rbd_test.hip

soft_body_test.hip

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From what I can see all my cameras set to render out position etc seem to be erroring regardless of if I manually set the bounding etc. Anyone else come a cross this and found a fix?  

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On 9/27/2017 at 2:50 AM, Gerbrand said:

Hey Neil. Thanks for the reply!

I think I did what you suggested, but the playback was jittery.

What I did was create a parameter node and plugged it into where the time node goes in the master material.

I don't know if there is a difference between a parameter, and a dynamic parameter as you suggested, but that's what i did.

The timeline in the blueprint was set to run from value 0 to 99, as I had 100 frames in my explosion.

I will try again, but if you can think of a reason why it would be jittery, please let me know.

If you have done this, and don't mind sharing a screenshot of your PB nodes and material nodes, it could maybe help me to double check what to do.

Thanks again

Gerbrand

Sorry for the delayed response, just now happened to see this.   I hope you found a solution.   So, for my setup, I'm wiring the Dynamic Parameter (which is for particle systems only) into a multiply, with the B input of the multiply being the speed parameter, which is set to 0.33.  In your setup, you would wire your parameter into A. Other than that, it is the standard setup. The only real difference between a parameter and a Dynamic Parameter is the Dynamic Parameter is a direct link to a particle system component.  The jittering may be coming from running it from 0 to 99.  In my case, I have 39 frames and I run it from 0 to 2.8.  I don't recall how I came up with that value.  I think I probably just fiddled with it until it looked right.    The jittering may also be coming from the UVs.  In the static mesh settings, Use High Precision UVs need to be ticked.  I haven't tried running one of these through blueprints yet, only through the particle system.  I'd start by trying to adjust the value range, seems like something around 6 or 7 may be a good place to start as the high end of it instead of 99. 

 

@Chris, try the latest version of the exporter from the github link if you haven't given that a shot yet.  That fixed some of the odd issues I was having.   I haven't tried the RBD export like this yet, only the soft body and fluid.  The soft body worked nicely, I used it to export a FEM simulation.  The fluid also worked well.  Though I do recall having to go through with different settings on the export a few times to get it right.   For the soft, I don't pack the normals since I've never got that working properly.  I also don't normalize the data.  In the output node, I had to dive into it, dive into the soft_obj node, then into the static mesh, then in there I had to wire the timeshift1 directly into the build_the_uvs node, bypassing the switch for the unwrap.  The switch is looking for a divide point attrib and that was failing for me.  Bypassing that bit fixed the issue though.  Hope some of this helps.  

 

Edited by LucidMovement
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Thanks for the tips Neil! 

I also have the soft method working

- still having odd rotation issues with RBD

- Sprites work perfectly except they are invisible?? regardless of what I do to the shade but you can see their moving correctly when highlighted so I'm sure that maybe a small fix

- Fluids I'm still getting the same results regardless of changing resolutions (texture/sim/etc) see the video below - any solutions for any of this would be super handy, :) 

Thanks Guys,

 

2017-10-11-1044-27.flv

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