Stereoscopic Camera Frusta Symmetries
Depending on your device's platform, plane geometry of the stereoscopic camera frusta may vary. For GearVR devices, the stereoscopic and monoscopic camera frusta are symmetric; however, for Rift devices, the stereoscopic and monoscopic camera frusta are asymmetric.
Please refer to the following diagrams to see how the camera frusta differ between GearVR and Rift devices.
GearVR (Symmetric Frusta)
Rift (Asymmetric Frusta)
As shown on the left, GearVR stereoscopic cameras have symmetric frusta, which means that the monoscopic camera shares the same projection matrix as the stereoscopic cameras.
On Rift devices, however, the stereoscopic cameras are asymmetric (the inward angle towards the nose is less than the outward angle), which means that the monoscopic camera's
frustum is the union of both the left and right frusta, which makes the monoscopic render target marginally bigger than the stereoscopic render targets.