% Short MATLAB example program that uses the Eyelink and Psychophysics
% Toolboxes to create a real-time gaze-dependent display.
% edf 09.19.06: adapted from http://psychtoolbox.org/eyelinktoolbox/EyelinkToolbox.pdf
% and http://www.kyb.tuebingen.mpg.de/bu/people/kleinerm/ptbosx/ptbdocu-1.0.5MK4R1.html
% (also available in local install at Psychtoolbox\ProgrammingTips.html)
% see also
% Psychtoolbox\PsychHardware\EyelinkToolbox\EyelinkDemos\Short demos\EyelinkExample.m
% which calls some functions that do not work on the windows openGL ptb
% ex: [v vs]=Eyelink('GetTrackerVersion') unimplemented for win
% also: el=EyelinkInitDefaults() sets el.keysCached to 0 on windows.
% this causes EyelinkDoTrackerSetup() and EyelinkDoDriftCorrect() to
% fail, because they call EyelinkGetKey(), which depends on cached key id's.
% updating the eyelink toolbox to use the new KbName('UnifyKeyNames')
% should fix this.
% necessary for windows:
% copy EyelinkToolbox144\EyelinkToolbox\EyelinkBasic\eyelink.dll
% (from http://www.psychtoolbox.org/eyelinktoolbox/downloads/EyelinkToolbox144.zip)
% to Psychtoolbox\PsychHardware\EyelinkToolbox\EyelinkBasic\Eyelink.dll
% (note capitalizing Eyelink.dll is important)
% the rest of the eyelink toolbox is included in ptb 1.0.6 openGL beta
% see ptb forum thread http://tech.groups.yahoo.com/group/psychtoolbox/message/4993
% note eyelink functions are documented in
% C:\Program Files\SR Research\EyeLink\Docs\*.pdf
function eyelinkWinDemo
format long g
KbName('UnifyKeyNames') %enables cross-platform key id's
doDisplay=1; %use ptb
createFile=1; %record eyetracking data on the remote (eyetracking) computer and suck over the file when done
mouseInsteadOfGaze=0; %control gaze cursor using mouse instead of gaze (for testing, in case calibration isn't worked out yet)
textOut=1; %write reports from tracker to stdout
edfFile='demo.edf'; %name of remote data file to create
screenNum = 1; % use main screen
% STEP 1
% Initialization of the connection with the Eyelink Gazetracker.
% exit program if this fails.
if (Eyelink('initialize') ~= 0)
error('could not init connection to Eyelink')
return;
end;
try
% STEP 2
% Open a graphics window on the main screen
% using the PsychToolbox's SCREEN function.
priority = MaxPriority('KbCheck');
oldPriority = Priority();
if doDisplay
AssertOpenGL
window = Screen('OpenWindow', screenNum, 0, [], 32, 2);
HideCursor;
Priority(priority);
ifi = Screen('GetFlipInterval', window, 200);
Priority(oldPriority);
white=WhiteIndex(window);
black=BlackIndex(window);
[scrWidth, scrHeight]=Screen('WindowSize', window);
xRange = [0 scrWidth]; %range of gaze estimates over display, which probably come in terms of the ptb stim display
yRange = [0 scrHeight];
dotHeight = 7;
dotWidth = 7;
end
% STEP 3
% Provide Eyelink with details about the graphics environment
% and perform some initializations. The information is returned
% in a structure that also contains useful defaults
% and control codes (e.g. tracker state bit and Eyelink key values).
if doDisplay
el=EyelinkInitDefaults(window);
else
el=EyelinkInitDefaults();
end
% make sure that we get gaze data from the Eyelink
status=Eyelink('command','link_sample_data = LEFT,RIGHT,GAZE,AREA,GAZERES,HREF,PUPIL,STATUS,INPUT');
if status~=0
error('link_sample_data error, status: ',status)
end
% open file to record data to (just an example, not required)
if createFile
status=Eyelink('openfile',edfFile);
if status~=0
error('openfile error, status: ',status)
end
end
% STEP 4
if doDisplay && strcmp(el.computer,'MAC')==1 % OSX
% Calibrate the eye tracker using the standard calibration routines
EyelinkDoTrackerSetup(el); %fails on win, see header comments
% do a final check of calibration using driftcorrection
EyelinkDoDriftCorrect(el); %fails on win, see header comments
else
warning('cannot do calibration/drift correction unless on OSX with an open ptb window')
end
% STEP 5
% start recording eye position
status=Eyelink('startrecording');
if status~=0
error('startrecording error, status: ',status)
end
% record a few samples before we actually start displaying
WaitSecs(0.1);
% mark zero-plot time in data file
status=Eyelink('message','SYNCTIME');
if status~=0
error('message error, status: ',status)
end
stopkey=KbName('space');
eye_used = -1; %just an initializer to remind us to ask tracker which eye is tracked
% STEP 6
% show gaze-dependent display
Priority(priority);
if doDisplay
vbl = Screen('Flip', window); %Initially synchronize with retrace, take base time in vbl
end
while 1 % loop till error or space bar is pressed
% Check recording status, stop display if error
err=Eyelink('checkrecording');
if(err~=0)
error('checkrecording problem, status: ',err)
break;
end
% check for presence of a new sample update
status = Eyelink('newfloatsampleavailable');
if status> 0
% get the sample in the form of an event structure
evt = Eyelink('newestfloatsample');
if textOut
evt
end
if eye_used ~= -1 % do we know which eye to use yet?
% if we do, get current gaze position from sample
x = evt.gx(eye_used+1); % +1 as we're accessing MATLAB array
y = evt.gy(eye_used+1);
% do we have valid data and is the pupil visible?
if (x~=el.MISSING_DATA & y~=el.MISSING_DATA & evt.pa(eye_used+1)>0) || mouseInsteadOfGaze
if mouseInsteadOfGaze
if doDisplay
[x,y,buttons] = GetMouse(window);
else
[x,y,buttons] = GetMouse(screenNum);
end
else
x=scrWidth*((x-min(xRange))/range(xRange));
y=scrHeight*((y-min(yRange))/range(yRange));
end
% if data is valid, draw a circle on the screen at current gaze position
% using PsychToolbox's SCREEN function
if doDisplay
gazeRect=[ x-dotWidth/2 y-dotHeight/2 x+dotWidth/2 y+dotHeight/2];
penSize=6;
Screen('FrameOval', window, white, gazeRect,penSize,penSize);
end
else
% if data is invalid (e.g. during a blink), clear display
if doDisplay
Screen('FillRect', window,black);
end
disp('blink! (x or y is missing or pupil size<=0)')
end
if doDisplay
Screen('DrawingFinished', window);
vbl = Screen('Flip', window, vbl + 0.5*ifi);
end
else % if we don't, first find eye that's being tracked
eye_used = Eyelink('eyeavailable'); % get eye that's tracked
switch eye_used
case el.BINOCULAR
disp('tracker indicates binocular, we''ll use right')
eye_used = el.RIGHT_EYE;
case el.LEFT_EYE
disp('tracker indicates left eye')
case el.RIGHT_EYE
disp('tracker indicates right eye')
case -1
error('eyeavailable returned -1')
otherwise
error('uninterpretable result from eyeavailable: ',eye_used)
end
end
else
disp(sprintf('no sample available, status: %d',status))
end % if sample available
% check for keyboard press
[keyIsDown,secs,keyCode] = KbCheck;
% if spacebar was pressed stop display
if keyCode(stopkey)
break;
end
end % main loop
% wait a while to record a few more samples
WaitSecs(0.1);
% STEP 7
% finish up: stop recording eye-movements,
% close graphics window, close data file and shut down tracker
cleanup(createFile, oldPriority, edfFile);
catch
cleanup(createFile, oldPriority, edfFile);
ers=lasterror
ers.stack.file
ers.stack.name
ers.stack.line
rethrow(lasterror)
end
function cleanup(createFile, oldPriority, edfFile)
Eyelink('stoprecording');
Screen('CloseAll');
ShowCursor;
Priority(oldPriority);
if createFile
status=Eyelink('closefile');
if status ~=0
disp(sprintf('closefile error, status: %d',status))
end
status=Eyelink('ReceiveFile',edfFile,pwd,1);
if status~=0
fprintf('problem: ReceiveFile status: %d\n', status);
end
if 2==exist(edfFile, 'file')
fprintf('Data file ''%s'' can be found in ''%s''\n', edfFile, pwd );
else
disp('unknown where data file went')
end
end
Eyelink('shutdown');
