void realizeInstance(const SBStateDigest& sbs) const {
// Initialize cache entries that will never be changed at later stages.
SBTreeVelocityCache& vc = sbs.updTreeVelocityCache();
SBTreeAccelerationCache& ac = sbs.updTreeAccelerationCache();
updV_FM(vc) = 0;
updV_PB_G(vc) = 0;
updVD_PB_G(vc) = 0;
}
void realizeInstance(const SBStateDigest& sbs) const {
// Initialize cache entries that will never be changed at later stages.
SBTreeVelocityCache& vc = sbs.updTreeVelocityCache();
SBDynamicsCache& dc = sbs.updDynamicsCache();
SBTreeAccelerationCache& ac = sbs.updTreeAccelerationCache();
updY(dc) = SpatialMat(Mat33(0));
updA_GB(ac) = 0;
}