0bf8096501
Damped Track by specification attempts to arrive at the desired direction via the shortest rotation. However with opposite vectors there are infinitely many valid 180 degree rotations. Currently it gives up and does nothing. I think that it would be more reasonable to resolve the ambiguity arbitrarily, so that Damped Track won't have a weird dead zone. To make it more predictable I use a local axis. In addition, the singularity area vicinity has some floating point precision problems that result in significant jitter. This applies workarounds for two causes of instability. Differential Revision: https://developer.blender.org/D3530