Stereo viewing is a common technique to increase visual realism or enhance user interaction with 3D scenes. Two views of a scene are created, one for the left eye, one for the right. Some sort of viewing hardware is used with the display, so each eye only sees the view created for it. The apparent depth of objects is a function of the difference in their positions from the left and right eye views. When done properly, objects appear to have actual depth, especially with respect to each other. When animating, the left and right back buffers are used, and must be updated each frame.
OpenGL supports stereo viewing, with left and right versions of the front and back buffers. In normal, non-stereo viewing, when not using both buffers, the default buffer is the left one for both front and back buffers. Since OpenGL is window system independent, there are no interfaces in OpenGL for stereo glasses, or other stereo viewing devices. This functionality is part of the OpenGL/Window system interface library; the style of support varies widely.
In order to render a frame in stereo:
Computing the left and right eye views is fairly straightforward. The distance separating the two eyes, called the interocular distance (IOD), must be determined. Choose this value to give the proper spacing of the viewer's eyes relative to the scene being viewed. Whether the scene is microscopic or galaxy-wide is irrelevant. What matters is the size of the imaginary viewer relative to the objects in the scene. This distance should be correlated with the degree of perspective distortion present in the scene to produce a realistic effect.