In EnSight, stereo display is enabled by pressing F12 on your keyboard. Pressing F12 again will return to normal display. The stereo separation angle can be controlled by pressing the F10 and F11 keys. F10 decreases the angle and F11 increases the angle. Pressing Ctrl+F12 will swap the left and right eyes in order to correct for stereo displays which have the left and right eyes reversed. When EnSight is configured to use a detached display (see Setup For Parallel Rendering), these commands affect only the detached display. The window remains monoscopic.
The stereo model used by EnSight to generate stereo imagery is one of two physical cameras. These cameras are located some distance from the screen and they are some distance apart. We render the right and left eye views using those two cameras. This will look (completely) correct, if your eyes are located at these two camera points. Unfortunately, we are not head-tracking in the case of desktop stereo, so it is very difficult to be perfectly aligned. Fortunately, the brain is very adept at compensating for the differences in projection and can tolerate an amazing level of inaccuracy in the projections (witness the fixed projection at your local 3D theater).
However, as geometry gets closer and closer to the eye, the compensation tends to fail. It also tends to fail when geometry near the border of the screen gets clipped. In those cases, the brain refuses to 'fuse' the imagery into a single 3D image. To compensate for this, EnSight allows you to vary the eye separation. You can use the function keys (F10 and F11) to adjust the stereo separation, or, you can adjust the number directly. Or you can use a tool included in the EnSight tools as shown further below. The command:
ensight.objs.core.STEREO_SEPARATION =
5.0
either in the Python command window or the command language command window (File → Command) or even in a command file (.enc file) or python file (.py file) adjusts the current value. These numbers are not in units of any specific distance (we would need to know the screen DPI for that) and are larger for eyes closer together and smaller for when they are further apart. Think of them as the distance the viewer is away from the screen, given a fixed intraocular distance. Thus, head position is implied. It is directly in the center of the imagery, as some distance back from the screen.
Double click on the Tools icon.
Open the Utilities folder, double-click the Stereo view properties tool to enable stereo and set eye separation.
On most platforms the display is not initialized by default in a mode which enables stereo viewing. In general quad-buffered stereo requires a refresh rate of 96Hz or higher. On some monitors it may be necessary to decrease the display resolution in order to accommodate this higher refresh rate. Check your monitor documentation before attempting to change the refresh rate.
There is a utility distributed with EnSight which can be used to
determine if your display has stereo capability. Run
cei_apex242_glinfo from a command line and look for
OpenGL visuals with a 'y' the column 'st' or 'stro'. If none exist,
then the current display parameters do not allow for stereo viewing.
Below are example instructions for various platform configurations which have been tested and confirmed to work with EnSight. When in doubt, refer to your system documentation for OpenGL as well as the X server (Unix) or video adapter device driver (Windows).
Linux
Professional graphics cards generally support stereo OpenGL under Linux. Documentation is included with the drivers, which may be downloaded from the card vendors web sites.
MS Windows
Configuration of stereo under Microsoft Windows is dependent upon the graphics card driver which is installed. Right-click the background and choose Properties to open to Display Properties dialog. Look for a tab which such as OpenGL Properties or Advanced and search for a stereo option. In many cases there is a toggle button for enabling stereo display.
The nVidia stereo-enabled graphics cards have a number of notes. Firsts, when you upgrade your graphics card software driver from the manufacturer's web site, your stereo may no longer work because it may be turned off as a result of the upgrade. And you may turn on stereo in the driver and find that the stereo test app works, but EnSight still fails. This is because the nVidia test app uses DirectX, but EnSight uses OpenGL. So while the nVidia test app is working in stereo because you have turned on DirectX stereo, EnSight may not be working because OpenGL is still turned off. In nVidia, the critical setting that allows OpenGL stereo is not under the Stereoscopic 3D settings, but is rather under Manage 3D Settings. Set Stereo Enable to On.
You will usually need to restart the machine in order for changes to take effect. If stereo still does not work, try changing the display resolution, as stereo may not be available at higher resolutions. Also, if you lowered the refresh rate below 120 Hz, put it back to 120 Hz.