In some instances, the number of control vertices of a hair could change mid-frame.
Cycles would then be unable to calculate proper motion blur for those hairs. This adds
interpolated CVs to fill in for the missing data. While this will not necessarily result in
a fully accurate reconstruction of the guide hair, it preserves motion blur instead of disabling it.
Reviewers: #cycles, sergey
Reviewed By: #cycles, sergey
Subscribers: sergey, brecht, #cycles
Tags: #cycles
Differential Revision: https://developer.blender.org/D3695
aa000400dc