Stereo

The OSG has support for stereo out of the box. Currently both anaglyphic stereo (i.e. red/green or red/cyan glasses) and quad buffered stereo (i.e. active stereo using shutter glasses, or passive stereo using polarised projectors & glasses). It is planned to extend this support horizontal and virtical split window stereo implementations.

Almost all OSG applications have the potential for stereo support simply by setting the relevent environmental variables, or via command line arguments. Little or no code changes will be required, the support is handled transparently inside osgUtil::SceneView's handling of rendering.

If the user is planning to use head tracked stereo, or a cave then it is currently recommend to set it up via a VR toolkit such as VRjuggler, in this case refer to the VR toolkits handling of stereo, and do not invoke the OSG's native support, i.e. keep all the OSG's stereo specific environment varibles (below) set to OFF, or set the values to off within own your own applications.

The environmental variables of interest:

OSG_STEREO	ON	turn stereo on.
OSG_STEREO	OFF	turn stereo off (default)
OSG_STEREO_MODE	ANAGLYPHIC	use anaglyphic stereo when in stereo (default).
OSG_STEREO_MODE	QUAD_BUFFER	use quad buffered stereo when in stereo.
OSG_SCREEN_DISTANCE	0.50	set the distance the viewer is from screen in metres (default shown)
OSG_SCREEN_HEIGHT	0.26	set the height if image on the screen in metres (default shown)
OSG_EYE_SEPERATION	0.05	set the eye seperation - interoccular distance (default shown.)

Command line arguments can be used to override these settings:

-stereo		Switch on stereo.
-stereo	ON	Switch on stereo.
-stereo	OFF	Switch off stereo.
-stereo	ANAGLYPHIC	Switch on ANAGLYPHIC stereo.
-stereo	QUAD_BUFFER	Switch on QUAD_BUFFER stereo.

Examples:

To invoke stereo from the comandline:
sgv -stereo cow.osg

To invoke quad buffered stereo from the commandline:
sgv -stereo QUAD_BUFFER cow.osg

To force all apps to start up in quad buffered stereo (if system supports it)
    export OSG_STEREO=ON
    export OSG_STEREO_MODE=QUAD_BUFFER
    sgv cow.osg

To set quad buffered stereo to the default, but use the commandline to switch stereo on:
    export OSG_STEREO=OFF
    export OSG_STEREO_MODE=QUAD_BUFFER
    sgv -stereo cow.osg

Size matters:

For appropriate depth perception the stereo code creates seperate left and eye views, both the frustum and modelview are shifted to account for the seperate eye views. To achieve the right amount of adjustment the OSG requires the users eye seperation, the distance from the eyes to the screen and the height of the screen. The OSG will use the defaults of 0.05m,0.5m and 0.26m respectively which are assumed to be reasonable defaults for most users workstation configurations, note the OSG_SCREEN_HEIGHT is the image height rather than total size of your monitor/display surface. For the best stereo effects please measure these values and set them up via the environmental variables. Once set the views you get should give improved depth perception.