Each different output display renders the scene from the current camera's position, using a frustum that is defined by a rectangle of with a defined size and placement in the 3D VR space. Each of these rectangles is defined by a screen configuration. Usually, each of these projection screens has the same dimensions in VR space as the physical screen that you'll use to render it.
The pivot point of a screen is always in its exact midpoint.
This definition describes a screen that is 3 meters by 3 meters screen, directly in front of its parent. Because the pivot point of the screen is at the center of the rectangle defined by the size parameter, we add a 1.5 meter offset on the Z axis to move the screen upward by half its height.
[screen] id=screen_front loc="X=1.5.Y=0,Z=1.5" rot="P=0,Y=0,R=0" size="X=3,Y=3" parent=screens
To define a screen on the left side of the viewer, we move it to the left (negative values on the Y axis), and rotate it around its local Y axis (yaw),
[screen] id=screen_left loc="X=0,y=-1.5,Z=1.5" rot="P=0,Y=-90,R=0" size="X=3,Y=3" parent=screens
||A unique name for this screen configuration.
||The location of the center of this screen in VR space, relative to its parent.
||The pitch (P), yaw (Y) and roll (R) angles of the screen's facing direction, in degrees.
||The total size of the screen rectangle along its local X and Y axes, in meters.
||The name of a scene_node configuration that you want to act as the parent for this object. This parameter is optional. If you specify a parent, the values you set in the loc and rot parameters will be relative to the position of that parent. If you omit the parent, the values you set in the loc and rot parameters will be relative to the VR root.