Wearing a VR headset , I’m immersed in a virtual speakeasy of the 1920s. A strange-looking wooden protagonist, played by a human actor whose footage has just been recorded, chit-chats with computer-generated bar patrons.

The technology I’m testing was created by Technicolor and allows film directors to instantly see what a scene will look like with computer-generated imagery added in.

With a touch of a joystick I can “fly” around the room to get a different point of view for the perfect shot, or shrink myself relative to …