Nice! Thank you!

Thanks for that info, Mike! I will mess with it shortly and see if I can get it working.

I guess no one has had this issue, or no one has solved it?

For what it's worth, I've got Houdini 17.5.229 and mine is working correctly in UE4. I updated my games tools shelf a couple days ago.

I recently had a problem using a fluid sim material that I'd created a while ago using Houdini's VAT output. I found that the material had been updated in Houdini, and the one I had created earlier was outdated. I seem to remember it screwing things up. When I created a new material from the new Houdini VAT output, it worked fine.

I am, however, having some other issues using the fluid sim in game.

OK, here's another problem. I added the fluid sim mesh as a component to a Blueprint object that a character is holding. Unfortunately, when I do this, the blueprint object correctly slaves to the hand, but the fluid sim appears to be attached to his waste. Is there any way around this?

Also, if I drop the fluid sim mesh directly into the world, it plays correctly. I can move, rotate, and scale it correctly, too. It's just when it's inside another BP that it gets screwed up.

Hi, I'm trying to use a fluid sim vertex animation in Unreal 4. I'm able to get my sim imported and working nicely as a fluid sim, but I'm running into a couple of major blockers when I try to use it in game.

1) When I add my mesh to a Blueprint, it shows up at origin, and I can't move it at all! I can scale and rotate it, but nothing I can do will move the mesh away from the Blueprint's origin.

2) If I attach the mesh to anything moving, which I really want to do, the motion blur goes crazy. I think it must be blurring based on the motion of the actual polys or points, which are moving in a crazy way under the hood.

Are there workarounds for either of these problems? I don't think I'll be able to use this tech unless I can solve them.

Thank you!
Brian

Oddly, if I import the fbx inside the destructible mesh as fbx chunks, it comes in rotated correctly. This is a problem because now the static mesh and the destructible chunks don't line up.

Well, I rebuilt most of my graph from scratch testing the export at many points, and the normal problem never showed up again. I really don't know what it was, but maybe there was some attribute I had added that screwed up exporting? This was really strange. I've had this same problem before, and I still don't know how to solve it or what causes it.

The rotation problem still happens every time when I import a static mesh. It's 90 degrees rotated. I tried changing the import rotation in the import settings and reimporting it, but it had no effect. Does anyone know what could cause that, or how to fix it?

Thanks again,
BK

I'm having a problem trying to export geometry for use in Unreal. When I import my exported fbx into Unreal, the normals are all reversed and the object is rotated 90 degrees. If I import the fbx to Maya, the orientation looks correct, but the normals are not.

Here are some steps to repro this problem:
I fracture my geometry, then apply a Normal node to create correct normals. I'm not using packed geometry.
I then use the Static Fracture Export node to export some fractured pieces for use as destructible mesh chunks in Unreal.
I export the FRACTURE_CONTAINER obj using File/export/Filmbox FBX…

Things I've tried:
Reverse normals in Houdini and then export. No fix.
Export to fbx with regular houdini normals, then open in maya and reverse normals. No fix.
Swizzle @P and @N various directions using point/vert wrangles. No fix.

Is there some setting somewhere I can change that will correct this? What am I doing wrong?

Thanks!
BK

I figured it out! The normals ARE in fact rendering correctly. They are just rendering in a different channel, and you can't see it in photoshop. You can see it in mplay if you switch from the C channel to the N channel. Also, the packed map and other tiled maps DO show up correctly (and you'll probably find them in the $HIP/export folder).

Just thought I'd post in case anyone else is running into this.

I'm getting the same problem. Have you figured this out?

OK, I've tried setting up some keyframe anims using the method you describe. It did work, but I ran into a couple problems.

First, when I rotate a piece, it rotates around the origin instead of around its centroid. I assume this has something to do with the difference between rotation and the orient attribute. I tried using a Point Wrangle that set the orient values numerically, but this was really difficult to get a good result with. Is there a more graceful way of animating rotation on individual rbd packed chunks?

Second, when I translated the objects, I had to enter values numerically in the transform. I couldn't get a transform handle to show up at all. This made it pretty difficult to hand animate the objects. I was able to get the look I needed doing it this way, though, so I could live with this method if necessary. Is there a way to get the transform handle showing up when animating these rbd chunks?

I've attached my current results.

Thanks for this info, Mike! Your solution for the Point VOP animation worked perfectly. I've attached a .hip file of the working version in case anyone wants to see it.

For anyone else reading this thread- the fact that the orient attribute is immutable explains a lot. For example, I could not get changes on orient to show up on my Point VOP node, even though the attribute had correct values in the Geometry Spreadsheet. But, the if I used the output from the animation DID show up correctly if I used the output from the Point VOP to transform the original pieces. Setting my Transform Pieces node to copy the orient attribute made it export correctly using the Vertex Animation Tool. It worked great in UE4.

I will try to get keyframing by hand working next.

I'm trying to do a rigid body simulation and then modify the animation with a Point VOP. For this example, I'm shattering a cube, then using a Point VOP to lerp it back to it's original transform. Unfortunately, when I export this as a Vertex Animation using the Game Development Tools, the rotation texture comes out all gray, and the pieces don't rotate. If I export the sim itself without any modifications, it works fine.

I've attached a hip file of my experiment. I assumed I could drive the RBD Packed pieces using the modified point locations from the sim. Am I doing something wrong? Is there a better way to do this?

Alternately, I would love to find a way to add keyframes individual simulated chunks. I tried to follow this tutorial, but I couldn't find a way to animate the RBD packed pieces individually:
http://www.sidefx.com/docs/houdini/dyno/keyframe.html [www.sidefx.com]

Is there documentation somewhere on how to do this with RBD packed objects?
I'm using Houdini 16.0.633, and I have the latest Game Development Tools as of today.

Thanks again,
BK

Nice, thank you!

Thanks for this tip! I've definitely done some similar exploration, and I'll be doing more shortly.

BK

Thanks for the link! I will check it out.

Oh, awesome. Thanks a ton for digging into this! I'll post when I have it working. Unfortunately, I'm home sick today, or I'd try it right now.

Oh, good to know. Thanks! I have an idea for a hack that will work for me right now- in UE4, I will try ramping down the vertex offset to zero on the first frame. That should let me get my shattered object looking whole.

Hi, Mike,
I thought of that, my min and max values are all between 100 and -100. If you have time to take a look, I've attached a very simple test hip file. It's just a shattering cube. When I bring it into Unreal and set up the material, I get something like the attached image. I am using full precision UVs, and I've tried both normalizing and not normalizing data. I'm sure I'm setting something up wrong. Do you have any suggestions?

Thanks again!