Baking simulations in linked groups

Support Particles and Physics Simulations
#1

Hi everyone. I have a problem which I’m not sure how to solve: I want to animate a character which I’m linking from another blend file. I begin by opening the blend of my scene, selecting the Link option, browsing and selecting the file containing my character, and linking its group. You cannot select individual objects in a group instance… so I then select the group and use the Make Proxy option on the rig, which creates a duplicate of the armature and lets me select and animate it separately.

The problem is what I do if my character contains hair or cloth simulations: How do I change the start and end frames of the caches to match those of my scene, as well as bake or free the bakes of my caches? I can’t select the mesh because it’s instanced through a group, unless I also use Make Proxy on it which I wish to avoid doing for more than just the armature. Are there any tricks to make the caches automatically start / end with the scene and to bake / free the simulations?

#2

I remember reading somewhere that typing #frame in a field will cause that field to assume the value of the current frame. While this seems to work for things like the noise seed in Cycles, it doesn’t appear I can use it for the End parameter of a simulation cache, nor can I even keyframe this parameter. Any other ideas, and is there a possible solution at all?

#3

Still eagerly waiting for an answer, if anyone knows what can be done to work around this please.

Like I said: I have a character intended to be linked as a group, and animated by making the armature a proxy. While this allows for the character to be fully posed and animated, it also contains hair particles with dynamics, cloth simulations, possibly even fluid simulations. Is there a way to make these automatically work while duplicated as a group, without having to Make Proxy each object involved? Thanks.

#4

Since there hasn’t been an answer here, I reported this as a problem on the dev tracker as well:

https://developer.blender.org/T44696

If anyone more knowing in the matter sees this, I would appreciate a reply. I’m already animating a linked character, and there is virtually no way to bake the dynamics on the particle hair :frowning: Is there at least some sort of workaround, or another way besides baked physics to make hair particles realistically sway? Thanks.

#5

A hint to get you going, at least with cloth:

In the ‘library’ file I had to de-select ‘Use lib path’ in the bake settings. This lets each scene/shot create its own cache directory and files.

But you need to trick blender by baking a couple of frames within the library file. This must flag some magic data value that lets the process work. So I would just bake 2 frames as a disk cache, then when linking the rig into your scene you are able to bake a new cache.

Then in the scene file, you also need to trick Blender again. Otherwise you can’t select the cloth object to bake:

  1. Select your character rig (or probably any object)
  2. Click the ‘object’ tab in the properties panel
  3. At the top of the panel, click the ‘pin’ icon to keep fixed datablock displayed
  4. In the object browser dropdown, you should now be able to select the clothing object that’s linked in
  5. You should now be able to access the linked clothing object’s physics settings for baking

Hope this gets you a bit further. I haven’t tried this with other soft-bodies but I think the same system should work OK. Good luck.

1 Like
#6

Thank you for the info, I shall look into that! One of the Blender maintainers also mentioned that a solution for this might be worked on, so I guess I’ll have to wait and see for that too.