>Psychtoolbox>PsychGLImageProcessing

SetCompressedStereoSideBySideParameters(win, [0, 0], [0.5, 1], [0.5, 0], [0.5, 1]);

Change parameters for over-under stereo to side-by-side stereo so that
the imaging mode will work in a display that horizontally stretches left
and right frames to fill the full res window.

This routine is called automatically by PsychImaging() during onscreen
window creation with its default parameters if …

PsychImaging(‘AddTask’, ‘General’, ‘SideBySideCompressedStereo’);

… is called during window setup.

You can call the function yourself after PsychImaging(‘OpenWindow’, …);
if you want to use non-default composition parameters for side-by-side
stereo presentation.

This is how compressed side-by-side stereo works:

1. Usercode draws stimuli into the left-eye and righ-eye framebuffers at
   full display resolution.

2. Screen(‘Flip’) compresses those stimuli horizontally into the output
   framebuffer.

3. At display time, the display stretches half frames to full width:
   _________ _________ _________
   | L | R | —> | <-L-> | + | <-R-> |
   ——— ———- ———-

Side-by-side compressed images are one of several popular stereo HDMI
formats.

The stereo mode must have been set to 2 or 3 for this to work, or the
above mentioned PsychImaging() function must have been called for setup.

Example function call:

SetCompressedStereoSideBySideParameters(win, [0, 0], [0.5, 1], [0.5, 0], [0.5, 1])

Call this function after the win = PsychImaging(‘OpenWindow’,…); call
on an onscreen window in Top/Bottom stereo mode to change the parameters
of drawing the stereo views.

All parameters except the onscreen ‘win’dowhandle are optional and have
reasonable builtin defaults:

‘leftOffset’ = Top-Left [x,y] offset of left eye framebuffer in relative
coordinates [0,0] == top-left of framebuffer, [1,0] == 1 display window
width to the right, [2,0] == 2 display window widths to the right etc.

‘leftScale’ = Scaling of left eye image buffer. E.g., [1,1] == Don’t
scale. [0.75, 0.5] scale to 75% of original width, 50% of original
height.

‘rightOffset’, ‘rightScale’ == Ditto for right eye image.

This function was inspired and co-implemented by David Hoffman.