Press the Make Compositing Child button in the track header for tracks 2 & 3. First make tracks 2 & 3 a child of track 1 using the Make Compositing Child button for both tracks. Now to control the two tracks in unison we do two things.This will push the video for that track back. Press the Track Motion button on track 3 and in the Track Motion window, set the Z Position to 240. Now that all three tracks have Track Motion set to 3D Source Alpha, let’s go back to the bottom track (3) which holds the Back Plane and push it back in 3D space.Your tracks should look like the image below with all three in 3D Composite Mode.To do this Press the Composite Mode button in the track header and select 3D Source Alpha from the dropdown list. Next we want to change the Compositing Mode for all three tracks to 3D Source Alpha.We’ll also change the background color of the Generated Media Text to make it more easily identifiable. Let’s add a Sony Text Generated Media on each track. For this tutorial we will add Generated Media but you can use any video you want.We’ll name these “ 3D Parent”, “ Front Plane” and “ Back Plane”. We start by pressing Ctrl+Q three times to add three tracks to the Vegas timeline.For this to work in 3D, all three tracks must be in 3D mode. The secret to controlling multiple tracks in unison is to use Parent Motion. A nice 3D effect is the ability to have two videos fly through space parallel to each other.
