I’ve been working specifically with the idea of a VR movie in mind, so to help out, I figured I’d let you know what I learned.
It is possible to get cameras to still follow the matinee path, and allow for HMD rotation, but you have to understand how it is matinee is controlling the cameras. It’s not that the tracking isn’t occurring (because it still is) but rather, it’s because Matinee overrides the camera’s position and rotation information after the camera is updated for the HMD. The way I got around this was to use blueprints to re-add the tracking information to the camera during the OnTick event. (technically, I based the blueprint on a camera actor, which doesn’t use the on-tick event, so I had the gamemode on-tick get all the cameras and update them).
For the Elemental demo specifically, it’s a little bit of a pain to set up, but you need to replace the default camera’s that matinee uses one at a time with the special cameras, and make sure the correct ones get re-added to the camera groups that control them. Also, replacing the cameras will remove the camera settings (like exposure and post-processing) so you have to record and copy those to your new cameras.
If you want to take a more direct route and you have downloaded the full source, you could probably instead go into the Interpolate.cpp and find where the movement track updates the camera’s information and apply the offset there.
Anyway, that’s my understanding of the matter. Hope that helps.