johnLIC
I'm using the VAT method to create RBD simulations for Unreal. Is there a way to create collision geometry? I created prim groups per piece that are named with this code:

string pieceName = prim(0, "name", @primnum);
string groupName = "rendered_collision_geo_ucx_multi" + pieceName;
setprimgroup(0, groupName, @primnum, 1);

It seems like the VAT ROP does not export the group membership. Is it possible to collide with VAT geometry? Is there an demoscene that illustrates how to do it?

Vertex animation in general does not support collision. The animating of the vertices happen later in the rendering pipeline on GPU after the collision has already be calculated. In other words, the physics engine will not be aware that the vertices have moved to different positions. You can use Labs RBD to FBX tool to export your destruction as skeletal mesh to get collision.

johnLIC
Is there a way to create collision geometry?

I would really, really warn you not to force animate collisions in your engine. Very likely you'll get a problems with the force "shooting" by your characters/environmental stuff.

I only can advise to create collisions and to export into your engine without animation. Just for in-engine simulation only.

BagMan64
Once you have your VAT set up in UE4, is there a way to add the instanced material/control it in the sequencer, so it doesn't keep looping?

If you create a Material Parameter Collection with a scalar called time (or whatever... but call it time) then reference that in the master material plugged into the time input of the VAT function, you'll be able to access it in sequencer and then animate the time as you see fit to start\stop etc.

kypo
Hey MaiAo

Sorry, I mistakenly forgot to add the FBX. I've attached it to this post.

I did try and remake the FBX in Houdini but had some extreme results in unity

I've also attached

LevelGen_Test.hip

Thanks

Hey, sorry I just got around to look at your question.

What you need to do is exporting the following attributes from the RBD Solver. Those attributes are expected by VAT ROP. Please see if that fixes your problem.

Hi, I'm having problem with the fisrt frame discrepancy that is mentioned in the Vertex Animation Textures v2.1 Unreal Quickstart https://vimeo.com/427443116/9bf1abac5f [vimeo.com]



This is the .hip file and the export



How can I go around it:S?

I know y'all warned me against creating collision geometry. I did it anyway. I am creating collision geometry only for the pieces that are inactive in the RBD simulations. The idea is that we want to leave parts of these destroyed things, like railings, in place and have them continue to be colliders. I am exporting a single fbx that has both the render mesh and the collision mesh in it, with the UCX_blah geo name for the collider.

It seems like the POS and ROT texture maps are getting confused by the additional prims of the collision geo. Is there a way to segregate the render prims from the collision prims? Am I confused about the problem I have? Basically I get a ball of voronoi chunks that are not where they are supposed to be. I suspect the added collision geo is causing the VAT animation to get screwed up.

It works. I was probably pulling in the wrong fbx files before.

I'm running into the same issues others have posted here with animations looking off when imported into Unity. I've added the attribute transfer on the RBD Bullet Solver like has been suggested, but I'm still having no luck.





Any chance the HIP file used for https://vimeo.com/427443045/6b6f9f63f4 [vimeo.com] could be shared as an example of what a proper configuration looks like?

Update - Solved

For anyone else working in Unity 2019.4, the problem was that the default color space is not set to linear (Project Settings > Player > Other Settings > Color Space). Setting it to linear fixed the issues I was having.

lab UE content plugin-->SideFX_Utilities_BP broken, "by class" node error, UE 4.26.2 -- LAB 18.5.563 -- VAT ROP 2.1

MaiAo

kypo
Hey MaiAo

Sorry, I mistakenly forgot to add the FBX. I've attached it to this post.

I did try and remake the FBX in Houdini but had some extreme results in unity

I've also attached

LevelGen_Test.hip

Thanks

Hey, sorry I just got around to look at your question.

What you need to do is exporting the following attributes from the RBD Solver. Those attributes are expected by VAT ROP. Please see if that fixes your problem.

Hi MaiAo.

Thanks for looking at the previous scene. Sorry it's taken a while to reply, I've had licensing issues. I altered the bullet solver with the changes you mentioned but the results still look incorrect.

Image Not Found

I've attached an updated version of the scene.

Thanks.

I'm doing RBD VAT simulations for Unreal. Occasionally, in Unreal, a few vertices will lose track of their Pos or Rot and get stuck, resulting in pieces smearing across space. It seems to start happening near the end of the simulation.

Has anybody got a fix for that?

Meh - the problem was coming from the Detail panel of the Material Fracture node. I'll see myself out.

MaiAo

Mary537
Hi,
I need to import a RigidBody simulation in Unreal exported by VAT, but after I'm defining the material values and textures the asset has holes. How can I solve?
Another question: How can I create LODs for my simulation with vertex animation?
I used Houdini 18.5.499, VAT 2.1 and Unreal 4.25 and 4.26

Hi, what you captured in the screenshot is a known bug with VAT-Rigid export mode. The fix is very very soon (April 27th Edit: the release data was pushed back; expected to come early May 2021). Stay tuned!

To your second question, you will unfortunately have to export separate meshes and textures for LOD purposes and control LOD using BP or code. Because the textures and exported vertices of the mesh are intrinsically mapped one-to-one, you cannot LOD the mesh in the traditional way and still be able to use the same vertex animation textures.

Heya, any update on that offset fix? Eagerly awaiting it here. Thank you

So targeting an Unreal crowds sim from Houdini. This thread is already a year old.

Is Vertex Animation Textures ROP 2.1 the latest version I should be looking at?

And is this setup still relevant?
https://vimeo.com/427443116/9bf1abac5f [vimeo.com]

art3mis
So targeting an Unreal crowds sim from Houdini. This thread is already a year old.

Is Vertex Animation Textures ROP 2.1 the latest version I should be looking at?

And is this setup still relevant?
https://vimeo.com/427443116/9bf1abac5f [vimeo.com]

2.1 will still work, but 3.0 is about to be released. Have been spending a lot of time on that. When the update comes, you can simply upgrade your tool and shaders. The workflow won't dramatically change, but it will be simplified.

Pumpkinking4
Heya, any update on that offset fix? Eagerly awaiting it here. Thank you

Almost done.

Hi, I'm trying to do a test with a simple box but unreal freaks out.
I'm using H18.5.598 Indie + Unreal 4.25.4
The scene and the cache inside the archive.
It only breaks with the "soft (constant topology) method. The "rigid" is fine.

Also, only "Set VAT Textures" script works for me.

Houdini view vs Unreal view

Enjoying the tool so far, thanks for all the hard work that has made it possible.

Quick question - I have a basic geo in Houdini with a VOP moving a few points around, it has normals and UV. I've exported it as a Soft VAT with 2.1 and imported it into a URP scene in Unity, all good. Normals look ok on my mesh in unity until I add the VAT material and then all my normals have gone funky? Why would this be? Thanks for the advice (I'm a total Unity newb).

JosefHeks
Enjoying the tool so far, thanks for all the hard work that has made it possible.

Quick question - I have a basic geo in Houdini with a VOP moving a few points around, it has normals and UV. I've exported it as a Soft VAT with 2.1 and imported it into a URP scene in Unity, all good. Normals look ok on my mesh in unity until I add the VAT material and then all my normals have gone funky? Why would this be? Thanks for the advice (I'm a total Unity newb).

You can select the brim edge loop and use a Facet SOP. Set group to your edge loop point group and turn on Unique Points. That will split the brim to get better normals. What you were seeing was due to the fact that VAT records data on per point basis,not per vertex basis, so hard edges will be not reflected unless you split the edge.

deviner
Hi, I'm trying to do a test with a simple box but unreal freaks out.
I'm using H18.5.598 Indie + Unreal 4.25.4
The scene and the cache inside the archive.
It only breaks with the "soft (constant topology) method. The "rigid" is fine.

Also, only "Set VAT Textures" script works for me.

Houdini view vs Unreal view

Unfortunately I can't reproduce the issue. But unlike what's in the screenshot, the pos min/max I am getting from your file is -54.59509 and 43.37052. Also have you tried using the MF_VAT_Soft from our content plugin (accessible on the VAT ROP interface via a button).

MaiAo

JosefHeks
Enjoying the tool so far, thanks for all the hard work that has made it possible.

Quick question - I have a basic geo in Houdini with a VOP moving a few points around, it has normals and UV. I've exported it as a Soft VAT with 2.1 and imported it into a URP scene in Unity, all good. Normals look ok on my mesh in unity until I add the VAT material and then all my normals have gone funky? Why would this be? Thanks for the advice (I'm a total Unity newb).

You can select the brim edge loop and use a Facet SOP. Set group to your edge loop point group and turn on Unique Points. That will split the brim to get better normals. What you were seeing was due to the fact that VAT records data on per point basis,not per vertex basis, so hard edges will be not reflected unless you split the edge.

Brilliant. Would have never worked that one out on my own!
Many thanks.

Can anyone tell me if you can make the material of the liquid transparent?
If I switch the material settings, the normals disappear and the liquid becomes flat.