Unpredictable particle physics caching for proxies?

Hi folks.

I’m using Blender 2.74 on both Windows and OSX.

I’m having lots of trouble rendering a scene file that links (with an armature proxy) to a character from another file, and I’m
hoping for help/hints.

Said character (in the linked file) includes three particle systems for hair. All (now) set to use local disk cacheing for physics data.

When I render (or just play an animation) over in the master file, all seems to be OK. The physics cache folder gets created
(blendcache_*), *.bphys physics data files appear, and the file renders correctly.

But when I render the scene file, it seems to be random chance whether the physics cache gets built. In many
cases, no blendcache_* folder appears, and the render proceeds as if physics was not even enabled. I’ve learned to watch
for this and can sometimes ‘force’ it by changing render and/or animation frame limits and restarting the render. This
workaround seems to work when I render under Windows. It has never worked when (as I sometimes do) I render on OSX (so
far, OSX has always rendered with no physics).

Is there some trick I’m missing when using a proxy? Do I have to run some additional step after linking the character group
and running ‘make proxy’ on the armature?

Any suggestions? Right now I’m thinking of stopping using the proxy mechanism just to get reliable renders.



Ah. OK.

I executed a self diagnostic (I rode home on my bicycle thinking about this), and thought of something…

I’m quite possibly starting rendering beyond the start point set in the ‘master’ file simulation frame range.

(Trying to save time by not rendering the physics ‘settling’ time). With no data cache in place, I bet
that’s why the physics isn’t ‘starting’.

I’ll check into that.


Well. I confirmed this morning that my first problem was indeed forgetting to reset the start frame to
frame 1 before render = no physics.

I still haven’t managed to get OSX to render the scene correctly though. It looks to me like a bug in
the physics settings. I always get what looks like ‘default’ particle settings, no good at all for my
stiffened hair. It ‘is’ now generating the expected blendcache* folder.

However, I can render exactly the same scene file under Windows (7.0) reliably now, and that
is my usual platform.

If I get a chance, I’ll try copying cached physics from Windows to OSX.

[EDIT: Copying the cached physics didn’t work. Blender isn’t fooled. It clears the folder and starts again]


Problem solved.

Another error on my part. I was running the previous version of blender on the Mac. It’s particle setup
is radically different, so probably had good reason not to work. Got that fixed, and it’s working.