function ImagingStereoDemo(stereoMode, usedatapixx, writeMovie, reduceCrossTalkGain)
% ImagingStereoDemo([stereoMode=8][, usedatapixx = 0][, writeMovie = 0][, reduceCrossTalkGain = 0])
%
% Demo on how to use OpenGL-Psychtoolbox to present stereoscopic stimuli
% when the Psychtoolbox imaging pipeline is enabled. Use of the imaging
% pipeline allows for more flexible and high quality stereo display modes,
% but it requires graphics hardware with support for at least framebuffer
% objects and Shadermodel 2.0. Any half-way recent graphics card provides
% those features as part of OpenGL 2.0. See the Psychtoolbox Wiki about
% gfx-hardware recommendations. The demo also shows how to configure the
% pipeline to restrict image processing to some subregion of the display,
% e.g., to save some computation time on low-end hardware.
%
% Press escape key to abort demo, space key to toggle modes of specific
% algorithms.
%
% Optional parameters:
%
% 'stereoMode' specifies the type of stereo display algorithm to use:
%
% 0 == Mono display - No stereo at all.
%
% 1 == Flip frame stereo (temporally interleaved) - You'll need shutter
% glasses that are supported by the operating system, e.g., the
% CrystalEyes-Shutterglasses. Psychtoolbox will automatically generate blue
% sync lines at the bottom of the display.
%
% 2 == Top/bottom image stereo with lefteye=top also for use with special
% CrystalEyes-hardware. Also used by the ViewPixx Inc. DataPixx device for
% frame-sequential stereo with shutter glasses, and with various other products.
%
% 3 == Same, but with lefteye=bottom.
%
% 4 == Free fusion (lefteye=left, righteye=right): Left-eye view displayed
% in left half of window, right-eye view displayed in right-half of window.
% Use this for dual-display setups (binocular video goggles, haploscopes,
% polarized stereo setups etc.)
%
% 5 == Cross fusion (lefteye=right ...): Like mode 4, but with views
% switched.
%
% 6-9 == Different modes of anaglyph stereo for color filter glasses:
%
% 6 == Red-Green
% 7 == Green-Red
% 8 == Red-Blue
% 9 == Blue-Red
%
% If you have a different set of filter glasses, e.g., red-magenta, you can
% simply select one of above modes, then use the
% SetStereoAnglyphParameters() command to change color gain settings,
% thereby implementing other anaglyph color combinations.
%
% 10 == Like mode 4, but for use on Mac OS/X with dualhead display setups.
%
% 11 == Like mode 1 (frame-sequential) but using Screen's built-in method,
% instead of the native method supported by your graphics card.
%
% 100 == Interleaved line stereo: Left eye image is displayed in even
% scanlines, right eye image is displayed in odd scanlines.
%
% 101 == Interleaved column stereo: Left eye image is displayed in even
% columns, right eye image is displayed in odd columns. Typically used for
% auto-stereoscopic displays, e.g., lenticular sheet or parallax barrier
% displays.
%
% 102 == PsychImaging('AddTask', 'General', 'SideBySideCompressedStereo');
% Side-by-side compressed stereo, popular with HDMI stereo display devices.
%
% 103 == Setup for stereo display on a VR HMD.
%
% 'usedatapixx' If provided and set to a non-zero value, will setup a
% connected VPixx DataPixx device for stereo display.
%
% 'writeMovie' If provided and set to a non-zero value, will write a movie
% file 'MyTestMovie.mov' into the current working directory which captures
% the full performance of this demo. A setting of 1 will only write video,
% a setting of 2 will also write an audio track with a sequence of ten
% successive beep tones of 1 sec duration.
%
% 'reduceCrossTalkGain' If provided and set to a greater than zero value, will
% make background 50% gray and demo the crosstalk reduction shader.
%
% Authors:
% Finnegan Calabro  - fcalabro@bu.edu
% Mario Kleiner  - mario.kleiner.de at gmail.com
%

% We start of with non-inverted display:
inverted = 0;

% Default to stereoMode 8 -- Red-Green stereo:
if nargin < 1
    stereoMode = [];
end

if isempty(stereoMode)
    stereoMode = 8;
end;

if nargin < 2
    usedatapixx = [];
end

if isempty(usedatapixx)
    usedatapixx = 0;
end

if nargin < 3
    writeMovie = [];
end

if isempty(writeMovie)
    writeMovie = 0;
end

if nargin < 4
    reduceCrossTalkGain = [];
end

% Check that Psychtoolbox is properly installed, switch to unified KbName's
% across operating systems, and switch color range to normalized 0 - 1 range:
PsychDefaultSetup(2);

% Define response key mappings:
space = KbName('space');
escape = KbName('ESCAPE');

%try
% Get the list of Screens and choose the one with the highest screen number.
% Screen 0 is, by definition, the display with the menu bar. Often when
% two monitors are connected the one without the menu bar is used as
% the stimulus display.  Chosing the display with the highest dislay number is
% a best guess about where you want the stimulus displayed.
scrnNum = max(Screen('Screens'));

% Increase level of verbosity for debug purposes:
%Screen('Preference', 'Verbosity', 6);

% Windows-Hack: If mode 4 or 5 is requested, we select screen zero
% as target screen: This will open a window that spans multiple
% monitors on multi-display setups, which is usually what one wants
% for this mode.
if IsWin && (stereoMode==4 || stereoMode==5)
    scrnNum = 0;
end

% Dual display dual-window stereo requested?
if stereoMode == 10
    % Yes. Do we have at least two separate displays for both views?
    if length(Screen('Screens')) < 2
        error('Sorry, for stereoMode 10 you''ll need at least 2 separate display screens in non-mirrored mode.');
    end
    
    if ~IsWin
        % Assign left-eye view (the master window) to main display:
        scrnNum = 0;
    else
        % Assign left-eye view (the master window) to main display:
        scrnNum = 1;
    end
end

% Open double-buffered onscreen window with the requested stereo mode,
% setup imaging pipeline for additional on-the-fly processing:

% Prepare pipeline for configuration. This marks the start of a list of
% requirements/tasks to be met/executed in the pipeline:
PsychImaging('PrepareConfiguration');

if usedatapixx
    % Tell PTB we want to display on a DataPixx device:
    PsychImaging('AddTask', 'General', 'UseDataPixx');
end

% Ask to restrict stimulus processing to some subarea (ROI) of the
% display. This will only generate the stimulus in the selected ROI and
% display the background color in all remaining areas, thereby saving
% some computation time for pixel processing: We select the center
% 512x512 pixel area of the screen:
%
% Update: Disabled, as it does more harm than good in this demo for
%         some display configurations. Still useful for your own code
%         if you have a weak graphics card or a very demanding task.
%
%if ~ismember(stereoMode, [100, 101, 102]) && isempty(reduceCrossTalkGain)
%    PsychImaging('AddTask', 'AllViews', 'RestrictProcessing', CenterRect([0 0 512 512], Screen('Rect', scrnNum)));
%end

% stereoMode 100 triggers scanline interleaved display:
if stereoMode == 100
    PsychImaging('AddTask', 'General', 'InterleavedLineStereo', 0);
end

% stereoMode 101 triggers column interleaved display:
if stereoMode == 101
    PsychImaging('AddTask', 'General', 'InterleavedColumnStereo', 0);
end

% stereoMode 102 triggers side-by-side compressed HDMI frame-packing display:
if stereoMode == 102
    PsychImaging('AddTask', 'General', 'SideBySideCompressedStereo');
end

% Trigger automatic setup of first detected VR HMD with
% default rendering parameters:
if stereoMode == 103
    PsychVRHMD('AutoSetupHMD', 'Stereoscopic');
    stereoMode = 0;
end

if stereoMode == 10
    % In dual-window, dual-display mode, we open the slave window on
    % the secondary screen:
    if IsWin
        slaveScreen = 2;
    else
        slaveScreen = 1;
    end
    
    % Tell PsychImaging that the 2nd window for output of the right-eye view should be
    % opened on 'slaveScreen':
    PsychImaging('AddTask', 'General', 'DualWindowStereo', slaveScreen);
end

% Experimental stereo crosstalk reduction requested?
if ~isempty(reduceCrossTalkGain)
    % Yes setup reduction for both view channels, using reduceCrossTalk as 1st parameter
    % itself. Second parameter sets the background luminance level.
    PsychImaging('AddTask', 'LeftView', 'StereoCrosstalkReduction', 'SubtractOther', reduceCrossTalkGain);
    PsychImaging('AddTask', 'RightView', 'StereoCrosstalkReduction', 'SubtractOther', reduceCrossTalkGain);
    bgColor = GrayIndex(scrnNum);
else
    bgColor = BlackIndex(scrnNum);
end

% Consolidate the list of requirements (error checking etc.), open a
% suitable onscreen window and configure the imaging pipeline for that
% window according to our specs. The syntax is the same as for
% Screen('OpenWindow'):
[windowPtr, windowRect] = PsychImaging('OpenWindow', scrnNum, bgColor, [], [], [], stereoMode);

if ismember(stereoMode, [4, 5])
    % This uncommented bit of code would allow to exercise the
    % SetStereoSideBySideParameters() function, which allows to change
    % presentation parameters for dual-display / side-by-side stereo modes 4
    % and 5:
    % "Shrink display a bit to the center": SetStereoSideBySideParameters(windowPtr, [0.25, 0.25], [0.75, 0.5], [1, 0.25], [0.75, 0.5]);
    % Restore defaults: SetStereoSideBySideParameters(windowPtr, [0, 0], [1, 1], [1, 0], [1, 1]);
end

% Stimulus settings:
numDots = 1000;
vel = 1;   % pix/frames
dotSize = 8;
dots = zeros(3, numDots);

xmax = RectWidth(windowRect)/2;
ymax = RectHeight(windowRect)/2;
if stereoMode == 100
    xmax = xmax/4;
    ymax = ymax/2;
else
    xmax = min(xmax, ymax) / 2;
    ymax = xmax;
end

amp = 16;

dots(1, :) = 2*(xmax)*rand(1, numDots) - xmax;
dots(2, :) = 2*(ymax)*rand(1, numDots) - ymax;

% Set color gains. This depends on the anaglyph mode selected. The
% values set here as default need to be fine-tuned for any specific
% combination of display device, color filter glasses and (probably)
% lighting conditions and subject. The current settings do ok on a
% MacBookPro flat panel.
switch stereoMode
    case 6,
        SetAnaglyphStereoParameters('LeftGains', windowPtr,  [1.0 0.0 0.0]);
        SetAnaglyphStereoParameters('RightGains', windowPtr, [0.0 0.6 0.0]);
    case 7,
        SetAnaglyphStereoParameters('LeftGains', windowPtr,  [0.0 0.6 0.0]);
        SetAnaglyphStereoParameters('RightGains', windowPtr, [1.0 0.0 0.0]);
    case 8,
        SetAnaglyphStereoParameters('LeftGains', windowPtr, [0.4 0.0 0.0]);
        SetAnaglyphStereoParameters('RightGains', windowPtr, [0.0 0.2 0.7]);
    case 9,
        SetAnaglyphStereoParameters('LeftGains', windowPtr, [0.0 0.2 0.7]);
        SetAnaglyphStereoParameters('RightGains', windowPtr, [0.4 0.0 0.0]);
    otherwise
        %error('Unknown stereoMode specified.');
end

% Set up alpha-blending for smooth (anti-aliased) drawing of dots:
Screen('BlendFunction', windowPtr, 'GL_SRC_ALPHA', 'GL_ONE_MINUS_SRC_ALPHA');

col1 = WhiteIndex(scrnNum);
col2 = col1;
center = [0 0];
sigma = 50;
xvel = 2*vel*rand(1,1)-vel;
yvel = 2*vel*rand(1,1)-vel;

Screen('Flip', windowPtr);

% Maximum number of animation frames to show:
nmax = 100000;

% Optionally create a movie file 'MyTestMovie.mov' in the current
% directory. The file will record a movie of this performance with video
% frames of size 512 x 512 pixels at a framerate of 30 fps.
if writeMovie
    if writeMovie > 1
        % Add a sound track to the movie: 2 channel stereo, 48 kHz:
        %
        % We raise video quality to 50% for decent looking movies.
        % Setting Videoquality is not strictly needed, as the default
        % encoder at default settings will create good looking video, but
        % we do it anyway, just to show you how.
        %
        % We also select Profile 2 for H264 encoding. Profile 2 is "Main Profile",
        % and that is about the maximum that deficient playback software like Apples
        % Quicktime player can handle. Without that setting, encoding would happen in
        % "High Profile" and stupid Quicktime would be unable to play movies. Other more
        % high quality open source players like VLC would of course handle such movies
        % without any problems.
        %
        % For more optional settings and a description of the syntax of the
        % optional 'movieOptions' string, read "help VideoRecording".
        movie = Screen('CreateMovie', windowPtr, 'MyTestMovie.mov', 512, 512, 30, ':CodecSettings=AddAudioTrack=2@48000 Videoquality=0.5 Profile=2');
        
        % Create a sequence of 10 tones, each of 1 second duration, each 100 Hz higher
        % than its predecessor. Each of the two stereo channels gets a slightly different sound:
        for freq=200:100:1100
            Screen('AddAudioBufferToMovie', movie, [0.8 * MakeBeep(freq, 1, 48000); 0.8 * MakeBeep(freq*1.2, 1, 48000)]);
        end
        nmax = 300;
    else
        % Only video, no sound:
        % We raise video quality to 50% for decent looking movies. See
        % comments in if-branch for more details about codec settings.
        movie = Screen('CreateMovie', windowPtr, 'MyTestMovie.mov', 512, 512, 30, ':CodecSettings=Videoquality=0.5 Profile=2');
    end
    
    % Other examples of valid and more low-level codec settings to allow
    % tighter control over the process:
    %
    %        % Use Schroedinger codec 'schroenc' with 'qtmux' QuickTime Multiplexer to encode 16 bpc Dirac video stream: (Decoding crashes though on GStreamer-1.4.0):
    %        movie = Screen('CreateMovie', windowPtr, 'MyTestMovie.mov', 512, 512, 30, ':CodecType=VideoCodec=schroenc gop-structure=1 ::: Muxer=qtmux', 4, 16);
    %
    %        movie = Screen('CreateMovie', windowPtr, 'WinXPTest.avi', 640, 480, 30, ':CodecType=VideoCodec=x264enc speed-preset=5 key-int-max=30 bitrate=20000 profile=3');
    %        movie = Screen('CreateMovie', windowPtr, 'WinXPTest.avi', 640, 480, 30, ':CodecType=VideoCodec=x264enc speed-preset=5 bitrate=20000 profile=3');
    %        movie = Screen('CreateMovie', windowPtr, 'WinXPTest.avi', 640, 480, 30, ':CodecType=theoraenc');
    %        movie = Screen('CreateMovie', windowPtr, 'WinXPTest.avi', 640, 480, 30, ':CodecType=theoraenc AddAudioTrack');
    %        movie = Screen('CreateMovie', windowPtr, 'WinXPTest.avi', 320, 240, 30, ':CodecType=VideoCodec=xvidenc profile=244 max-key-interval=10 bitrate=9708400 quant-type=1');
    
    %        This may need reevaluation for GStreamer-1.x, only tested on 0.10:
    %        Encode yes, decode no: Lossless JPEG for 8bpc content:
    %        movie = Screen('CreateMovie', windowPtr, ['MyTestMovie.flv'], 512, 512, 30, 'gst-launch appsrc name=ptbvideoappsrc do-timestamp=0 stream-type=0 max-bytes=0 block=1 is-live=0 emit-signals=0 ! capsfilter caps="video/x-raw-rgb, bpp=(int)32, depth=(int)32, endianess=(int)4321, alpha_mask=(int)-16777216, red_mask=(int)16711680, green_mask=(int)65280, blue_mask=(int)255, width=(int)512, height=(int)512, framerate=30/1" ! videorate ! ffmpegcolorspace ! ffenc_ljpeg ! avimux ! filesink name=ptbfilesink async=0 location="MyTestMovie.mov"');
    %        Works for lossless RGB8 encoding, but loses A8 alpha channel:
    %        movie = Screen('CreateMovie', windowPtr, ['MyTestMovie.flv'], 512, 512, 30, 'gst-launch appsrc name=ptbvideoappsrc do-timestamp=0 stream-type=0 max-bytes=0 block=1 is-live=0 emit-signals=0 ! capsfilter caps="video/x-raw-rgb, bpp=(int)32, depth=(int)32, endianess=(int)4321, alpha_mask=(int)-16777216, red_mask=(int)16711680, green_mask=(int)65280, blue_mask=(int)255, width=(int)512, height=(int)512, framerate=30/1" ! videorate ! ffmpegcolorspace ! ffenc_huffyuv ! avimux ! filesink name=ptbfilesink async=0 location="MyTestMovie.mov"');
    %
    %        The lowest level, and most flexible, way to control movie
    %        writing is by specifying a so called "gst-launch line". You
    %        can find examples of gst-launch lines by searching the
    %        internet. If you run with Screen('Preference','Verbosity', 5),
    %        then Screen's debug output will also print out the launch line
    %        used by the system, so you can learn how to build valid launch
    %        lines for this function, take them as working baseline
    %        examples, and then tweak them to your needs. Be aware though
    %        that error checking and error handling is minimal with launch
    %        lines. Often all you'll get if something goes wrong is a
    %        somewhat cryptic error message, or botched movie files, or a
    %        hang of Matlab/Octave.
    %
    %        A full gst-launch style gstreamer launch line with everything
    %        manually controlled. This for Flash video encoding (.flv):
    %        movie = Screen('CreateMovie', windowPtr, ['MyTestMovie.flv'], 512, 512, 30, 'gst-launch appsrc name=ptbvideoappsrc do-timestamp=0 stream-type=0 max-bytes=0 block=1 is-live=0 emit-signals=0 ! capsfilter caps="video/x-raw-rgb, bpp=(int)32, depth=(int)32, endianess=(int)4321, alpha_mask=(int)-16777216, red_mask=(int)16711680, green_mask=(int)65280, blue_mask=(int)255, width=(int)512, height=(int)512, framerate=30/1" ! videorate ! ffmpegcolorspace ! ffenc_flv ! ffmux_flv ! filesink name=ptbfilesink async=0 location="MyTestMovie.flv"');
end

% Preallocate timing array for speed:
t = zeros(1, nmax);
count = 1;

% Perform a flip to sync us to vbl and take start-timestamp in t:
t(count) = Screen('Flip', windowPtr);
buttons = 0;

% Run until a key is pressed or nmax iterations have been done:
while (count < nmax) && ~any(buttons)
    
    % Demonstrate how mouse cursor position (or any other physical pointing
    % device location on the actual display) can be remapped to the
    % stereo framebuffer locations which correspond to those positions. We
    % query "physical" mouse cursor location, remap it to stereo
    % framebuffer locations, then draw some little marker-square at those
    % locations via Screen('DrawDots') below. At least one of the squares
    % locations should correspond to the location of the mouse cursor
    % image:
    [x,y, buttons] = GetMouse(windowPtr);
    [x,y] = RemapMouse(windowPtr, 'AllViews', x, y);
    
    % Select left-eye image buffer for drawing:
    Screen('SelectStereoDrawBuffer', windowPtr, 0);
    
    % Draw left stim:
    Screen('DrawDots', windowPtr, dots(1:2, :) + [dots(3, :)/2; zeros(1, numDots)], dotSize, col1, windowRect(3:4)/2, 1);
    Screen('FrameRect', windowPtr, [1 0 0], [], 5);
    Screen('DrawDots', windowPtr, [x ; y], 8, [1 0 0]);
    
    % Select right-eye image buffer for drawing:
    Screen('SelectStereoDrawBuffer', windowPtr, 1);
    
    % Draw right stim:
    Screen('DrawDots', windowPtr, dots(1:2, :) - [dots(3, :)/2; zeros(1, numDots)], dotSize, col2, windowRect(3:4)/2, 1);
    Screen('FrameRect', windowPtr, [0 1 0], [], 5);
    Screen('DrawDots', windowPtr, [x ; y], 8, [0 1 0]);
    
    % Tell PTB drawing is finished for this frame:
    Screen('DrawingFinished', windowPtr);
    
    % Now all non-drawing tasks:
    
    % Compute dot positions and offsets for next frame:
    center = center + [xvel yvel];
    if center(1) > xmax || center(1) < -xmax
        xvel = -xvel;
    end
    
    if center(2) > ymax || center(2) < -ymax
        yvel = -yvel;
    end
    
    dots(3, :) = -amp.*exp(-(dots(1, :) - center(1)).^2 / (2*sigma*sigma)).*exp(-(dots(2, :) - center(2)).^2 / (2*sigma*sigma));
    
    % Keyboard queries and key handling:
    [pressed dummy keycode] = KbCheck; %#ok<ASGLU>
    if pressed
        % SPACE key toggles between non-inverted and inverted display:
        if keycode(space) && ismember(stereoMode, [6 7 8 9]);
            KbReleaseWait;
            inverted = 1 - inverted;
            if inverted
                % Set inverted mode:
                SetAnaglyphStereoParameters('InvertedMode', windowPtr);
            else
                % Set standard mode:
                SetAnaglyphStereoParameters('StandardMode', windowPtr);
            end
        end
        
        % ESCape key exits the demo:
        if keycode(escape)
            break;
        end
    end
    
    % Add a screenshot of the center 512 x 512 pixels as a new video frame to the movie file, if any:
    if writeMovie
        % It would be better to capture the image from the 'backBuffer', but
        % we capture the 'frontBuffer' to work around a bug in the VirtualBox
        % Virtual Machine software when running a Windows-7 VM. This exotic
        % setup is used for testing of PTB, you should not need this
        % workaround on your system.
        Screen('AddFrameToMovie', windowPtr, CenterRect([0 0 512 512], Screen('Rect', scrnNum)), 'frontBuffer');
    end
    
    % Flip stim to display and take timestamp of stimulus-onset after
    % displaying the new stimulus and record it in vector t:
    onset = Screen('Flip', windowPtr);
    
    % Log timestamp:
    count = count + 1;
    t(count) = onset;
end

% Last Flip:
Screen('Flip', windowPtr);

% Finalize and close movie file, if any:
if writeMovie
    Screen('FinalizeMovie', movie);
end

% Done. Close the onscreen window:
Screen('CloseAll')

% Compute and show timing statistics:
t = t(1:count);
dt = t(2:end) - t(1:end-1);
disp(sprintf('N.Dots\tMean (s)\tMax (s)\t%%>20ms\t%%>30ms\n')); %#ok<DSPS>
disp(sprintf('%d\t%5.3f\t%5.3f\t%5.0f\t%5.0f\n', numDots, mean(dt), max(dt), sum(dt > 0.020)/length(dt)*100, sum(dt > 0.030)/length(dt)*100)); %#ok<DSPS>

% We're done.
return;
