Bullet Cache, Hierarchies and Bones

Bullet Cache

As Bullet solves dynamic calculations, it stores the results in a cache so that animation playback can be fluid. The cache is automatically stored in the ‘Dynamics’ folder of the current Content Directory for the scene (this can be changed in the Options > Paths window, which can be accessed by pressing the o key). The cache file is named the same as the scene file, but has a .dynacache extension.

To generate the full cache for a dynamics simulation, a quick way is to go to the end frame on the timeline, rather than pressing play. Either click on the last frame in the timeline, or bring up the Goto Frame window (F key). Doing it this way means that although LightWave has to calculate the simulation for the whole scene in one go, it doesn’t have to display every frame update in the viewport, resulting in quicker calculation times.

Bullet and Hierarchies

If you note that the motions of a parent object are not being updated in Bullet for a child object with Bullet applied, reset your dynamics cache on the World tab of Bullet Properties.

Bullet and Bones

You can parent a Bullet-controlled kinematic object to a bone and animate the bone using IK, targeting, etc. Bullet dynamics will read the motions.