A 3D graphics system like OpenGL is complemented by display hardware that supports stereo output. Usually, this is done using a monitor with double the normal refresh rate and special goggles that rapidly switch LCD shutters between the two eyes in synchronization with the video frame rate. The display continuously scans out the left eye view, then the right eye view, synchronized with the LCD goggle shutters.
OpenGL supports a quad buffering scheme (stereo is almost always double buffered; stereo also adds left and right buffers in addition to front and back). Quad buffered stereo requires extra frame buffer memory and fast monitor refresh rates so OpenGL stereo support is not currently common. To get the stereo effect, OpenGL applications rendering to a stereo window must render both the right and left views, each from a slightly different eye point.