Bake simulation to joints (maya)

jjoyal88

Im trying to take a simulation I made with a sphere exploding and get the animation to bake onto joints so I can bring it into UDK. Does anyone know how I would go about making the animations bake onto the joints so its not on the geometry itself,
Thanks

MoP

You could use Parent Constraints to link the joints to the geometry? Then just export the joints (you might need to bake the keyframes after that, not sure).

jjoyal88

Thanks for the reply.
I did those steps then I combined the mesh and weighted the correct pieces with the corresponding joints. Everything looked good so I exported using actorX and inside of UDK the whole mesh just follows one joint. I then made a root joint in maya and everything looked good again. Inside of UDK though it still only followed on joint. Is there something I could be missing inside of UDK?

Mark Dygert

You might have too many bones set to influence the verts? for UDK I think this caps out at 4?

jjoyal88

I have it set at an influence of 1.

Mark Dygert

That's probably the problem then. Only one bone is influencing the verts. If that's the export setting then it's going to pick the bone with the highest influence.

jjoyal88

I only want one bone influence per piece of geometry so its basically hard binding.

Mark Dygert

You're going to have to draw me a picture or attach an image I'm having trouble visualizing what you're trying to do. Sorry...

jjoyal88

http://img42.imageshack.us/img42/2826/sphere1.jpg
http://img132.imageshack.us/img132/9771/sphere2.jpg

I have the animation from the simulation baked onto the joints and the geometry is smooth binded to the joints with an influence of 1.

I see that the joints animation does not actually work. The channels for the joints are colored like they have animation but the animation doesnt actually change.

Lamont

This was brought up a while ago... hold on let me search it as it's hard to find.

Lamont

http://www.polycount.com/forum/showthread.php?t=76608

ivars

jjoyal88 wrote: »

I see that the joints animation does not actually work. The channels for the joints are colored like they have animation but the animation doesnt actually change.

In Maya?

Can you please show a screen of your hierarchy expanded in the outliner. And a shot of your construction history of your mesh.

jjoyal88

@Lamont Based on that thread what Im doing wrong is deleting the rigid bodies before adding the joints from what you wrote on how you did it. I will have to try that approach since Im doing all those steps just in the wrong order.

jjoyal88

@ivars The first image is with the pieces seperated and joints parented. The second is when the geo is combined and the joints weighted to the mesh. In the first image the geo still drives the joints since its parented and the second the shards are driving the joints. I just cant get the animations to bake onto the joints at all.
The mesh is just a polySphere I shattered using dynamics then applied a field to explode it. Then it is baked and the rigid bodies are deleted so only the baked on animation is effecting the geo.

http://img703.imageshack.us/img703/3816/screenshot20101207at312.png
http://img545.imageshack.us/img545/4537/screenshot20101207at313.png

ivars

I think I know what the problem is....

You see those transform-nodes in there? (shard#) That's the original transform-node from your pieces, and that still holds the animation that drives the joints. I think you've missed a few steps, one being deleting history on your combined mesh.

Do this:
- Start over from where you have the joints connected to the meshes with a parent-constraint. (It's very important it's a constraint, not parented)
- Select all the joints and bake the simulation (Edit > Keys > Bake simulation)
- Edit > Delete all by type > Constraints (Meshes and joint should still animate the same)
- Go to whatever frame you want to be your new mesh bindpose. (Let's say frame 0)
- Select all mesh-pieces and delete their keyframes, if they're animated. If they're just driven by dynamics, delete their rigid bodies)

(Notice that if you combine animated objects, the animation stays on the objects original transform nodes)

- While still on frame 0, combine the meshes and delete the construction history of the resulting mesh.
- Bind the new mesh to the complete skeleton, and skinweight.

The end result should look like this:

PolySurface1
Joint11
|- Joint10
|- Joint9
|- Joint8
|- Joint7
|- Joint6
|- Joint5
|- Joint4
|- Joint3
|- Joint2
|- Joint1

I'm not very familiar with UDK, but I think that should do it.

jjoyal88

@Ivars Thanks a lot I got it to work. I was just parenting and not constraining. I imported it into UDK using fbx and it wasnt working at first so I also had it exported using axmain and once I sampled the animation from the .psa file it worked just fine. Thanks again!