nwang Welcome Nelson!
Our zCache was written for the purpose of previewing your simulation choices when setting up your character, and was not really intended to be used as shot tool.
I blame myself for this misunderstanding, as we should really have named the node zPreview rather than zCache.
The reason why the zCache gets removed is likely because some aspect of the simulation state has changed between when that cache was generated and when you reloaded it and then jumped to the frame.
If you find it best to work with the tool in this way, it might be better to write out individual zCache files per frame.
Here is a little script that should help with that:
(longer term, we'll likely add a cache streaming from disk node to better service this use case)
# save cache per frame, then clear it #
# requires that you already have a ziva cache in the scene.
# some variation of this could be put in the per frame callback when exporting Alembic
s = 1
e = 10
out_dir = 'c:/tmp/'
for i in xrange(s, e+1):
mc.currentTime( i )
mc.zCache( save=os.path.join(out_dir, 'character_name.%i.zCache' % i ))
mc.zCache( clear=True )
# end
# load cache #
for i in xrange(s, e+1):
mc.zCache( load=os.path.join(out_dir, 'character_name.%i.zCache' % i ))
I hope this helps!
Looking forward to hearing any additional questions/feedback you might have.
Cheers!
-jj