Bigscreen lets you watch 3D movies and play 3D games in VR, with support for Side-by-Side (SBS 3D) and Over-Under (OU 3D) formats. Here's how you can enable SBS 3D in Bigscreen.
Go to the Customize Screen interface (the monitor icon) and select SBS or OU. The big screen will display your desktop in SBS/OU mode. The left half of the screen will show up in your left eye, and the right half of the screen will show up in your right eye.
Note: by default, your small screen in front of you remains in 2D mode, allowing you to use your computer normally. This can be changed in advanced options (see below).
By default, SBS 3D and OU 3D shows up on the big screen, and your small screen remains in 2D mode. This lets you use your computer normally.
If you want to only see 3D content on the big screen (and hide your small screen), or if you want to see 3D content on your small screen (and not show anything on the big screen), turn on the Allow 3D modes in any Display Option toggle.
Bigscreen also supports inverted 3D modes. Inverted SBS would show the left half of the screen in your right eye, and the right half of the screen in your left eye.