View Full Version : Preserving/Using Bullet *.dynachache

11-17-2014, 06:26 AM
How do you tell LW to USE an existing Bullet simulation's *.dynacache and NOT recalculate it when reopening a scene AND/OR to USE the cache for network rendering?

Every time I calc a Bullet sim and am happy with the results, save the scene, and confirm the timestamp and size of the *.dynacache file, then close and reopen the scene, LW wants to recalculate the simulation. Isn't the purpose of a cache to NOT have to recalc once the sim params are working as desired? Why aren't dynacache files treated the same as *.pfx files for LW's Particle system? Is there a step I'm missing in Bullet similar to the object properties FX tab to specify and "save" a cache file that is then remembered and used until explicitly forced to be cleared and recalculated?

I KNOW the "workaround" is to bake object motion(s) to MDD and read the *.mdd file back via plugin or nodes, but just wondering about the "per session" nature of dynacaches and why they can't be, aren't being, used for other sessions.

Ryan Roye
11-17-2014, 07:02 AM
If you're doing a hard body animation, just bake the keyframe motion and remove bullet; very simple.

regarding deforming bodies... the dynacache should be utilized when you open the scene, perhaps its a pathing issue? I would test this by setting the playhead to frame 500 or so, packaging the scene and then reloading it. It is possible that LW isn't seeing the cache file where it expects it to be.

Bullet caching works per-edit, not per session.

11-17-2014, 07:29 AM
This is a sim of 256 chains of 5 links each anchored around the outside of an 8' steel drum. So, 1,280 hard bodies in a single object layer (parts mode convex pieces in Bullet) plus 256 anchors and drum in another layer, plus 96 paddles (12 x 8 rows in a semi-spiral around the outside of the drum) they collide with (layer parented to anchor-drum layer). Baking to MDD works great, but just wondering why the dynacache isn't used for net rendering and limited to just the current session?