Creating a dynamic gaze follower with the TRACKPixx3
This demo requires TRACKPixx Revision 16 or later. You can check for recent firmware updates at http://vpixx.com/whatsnew
This demo is a simple interactive gaze follower. Thirteen dots are displayed on a black background, with the current x,y positions of the left and right eye overlaid. Users can toggle the follower on and off by pressing “U” (on) or “H” (off) on the keyboard. The follower can be set to display the position tracked from a single frame by pressing “D”, or the mean position of the last 10 recorded frames by pressing “F”. Clicking on fixated locations with the mouse will show the error between recorded eye position and screen location.
MATLAB
function TPxGazeFollow()
% TPxGazeFollow()
%
% This shows your current gaze position.
% Press L to load a calibration.
%
% Further Comments will be added on the next release.
%
% History:
%
% Dec 22, 2017 gm Written
clear all;
close all;
dummy = 0;
screen = 2;
KbName('UnifyKeyNames');
[windowPtr, windowRect]=PsychImaging('OpenWindow', screen, 0);
cx = 1920/2;
cy = 1080/2;
dx = 400;
dy = 250;
xy = [ cx cy;...
cx cy+dy;...
cx+dx cy;...
cx cy-dy;...
cx-dx cy;...
cx+dx cy+dy;...
cx-dx cy+dy;...
cx+dx cy-dy;...
cx-dx cy-dy;...
cx+dx/2 cy+dy/2;...
cx-dx/2 cy+dy/2;...
cx-dx/2 cy-dy/2;...
cx+dx/2 cy-dy/2;];
xy = xy';
Datapixx('Open');
Datapixx('HideOverlay');
Datapixx('SetTPxAwake');
Datapixx('RegWrRd');
fileID = fopen('gaze_measure.csv', 'a');
fileID2 = fopen('gaze_raw_compare.csv', 'a');
fprintf(fileID, 'mouse X,mouse Y,right eye x,right eye y,left eye x,left eye y,error rigth x,error right y,error left x,error left y\n');
visible = 1;
mfilter = 0;
xAvgRight = [];
yAvgRight = [];
xAvgLeft = [];
yAvgLeft = [];
xErrRight = [];
yErrRight = [];
xErrLeft = [];
yErrLeft = [];
while (1)
% 1- Get Eye position
% 2- Put that in array
% 3- Draw it on screen
DrawFormattedText(windowPtr, 'Following your gaze now!\n Press L to load calibrations', 'center', 700, 255);
Screen('DrawDots', windowPtr, [xy(1,:)' xy(2,:)']', [30]', [255 255 255]', [], 1);
if ~dummy
Datapixx('RegWrRd');
[xScreenRight yScreenRight xScreenLeft yScreenLeft xRawRight yRawRight xRawLeft yRawLeft] = Datapixx('GetEyePosition');
array = [xScreenRight yScreenRight];
array = Datapixx('ConvertCoordSysToCustom', array);
xScreenRight = array(1);
yScreenRight = array(2);
array = [xScreenLeft yScreenLeft];
array = Datapixx('ConvertCoordSysToCustom', array);
xScreenLeft = array(1);
yScreenLeft = array(2);
else
[X,Y] = GetMouse();
end
if (size(xAvgRight,1) < 10)
xAvgRight = [xScreenRight;xAvgRight];
yAvgRight = [yScreenRight;yAvgRight];
xAvgLeft = [xScreenLeft;xAvgLeft];
yAvgLeft = [yScreenLeft;yAvgLeft];
else
xAvgRight = circshift(xAvgRight,1);
xAvgRight(1) = xScreenRight;
yAvgRight = circshift(yAvgRight,1);
yAvgRight(1) = yScreenRight;
xAvgLeft = circshift(xAvgLeft,1);
xAvgLeft(1) = xScreenLeft;
yAvgLeft = circshift(yAvgLeft,1);
yAvgLeft(1) = yScreenLeft;
end
if ~dummy
if visible
if mfilter
Screen('DrawDots', windowPtr, [mean(xAvgRight); mean(yAvgRight)], [15]', [255 0 0]', [], 1);
Screen('DrawDots', windowPtr, [mean(xAvgLeft); mean(yAvgLeft)], [15]', [0 0 255]', [], 1);
else
Screen('DrawDots', windowPtr, [xScreenRight; yScreenRight], [15]', [255 0 0]', [], 1);
Screen('DrawDots', windowPtr, [xScreenLeft; yScreenLeft], [15]', [0 0 255]', [], 1);
end
end
else
Screen('DrawDots', windowPtr, [X; Y], [15]', [255 0 255]', [], 1);
end
[X, Y, buttons] = GetMouse(windowPtr);
if buttons(1)
if reset_error
xErrRight = [];
yErrRight = [];
xErrLeft = [];
yErrLeft = [];
reset_error = 0;
end
fprintf(fileID, '%f,%f,%f,%f,%f,%f,%f,%f,%f,%f\n',...
X, Y, xScreenRight, yScreenRight, xScreenLeft, yScreenLeft,...
(X - xScreenRight), (Y - yScreenRight), (X - xScreenLeft), (Y - yScreenLeft));
fprintf(fileID2, '%f,%f,%f,%f,%f,%f,\n', X, Y, xRawRight, yRawRight, xRawLeft, yRawLeft);
if (size(xErrRight,1) < 20)
xErrRight = [X - xScreenRight;xErrRight];
yErrRight = [Y - yScreenRight;yErrRight];
xErrLeft = [X - xScreenLeft;xErrLeft];
yErrLeft = [Y - yScreenLeft;yErrLeft];
else
xErrRight = circshift(xErrRight,1);
xErrRight(1) = X - xScreenRight;
yErrRight = circshift(yErrRight,1);
yErrRight(1) = Y - yScreenRight;
xErrLeft = circshift(xErrLeft,1);
xErrLeft(1) = X - xScreenLeft;
yErrLeft = circshift(yErrLeft,1);
yErrLeft(1) = Y - yScreenLeft;
end
Screen('TextSize', windowPtr, 16);
Screen('Preference', 'TextAlphaBlending', 1);
Screen('TextBackgroundColor', windowPtr, [250 248 200]);
DrawFormattedText(windowPtr, sprintf(' %f | %f\n %f | %f', mean(xErrRight),mean(yErrRight),mean(xErrLeft),mean(yErrLeft)), 'right', [], 10);
Screen('Preference', 'TextAlphaBlending', 0);
elseif buttons(3)
Screen('TextSize', windowPtr, 16);
Screen('Preference', 'TextAlphaBlending', 1);
Screen('DrawText', windowPtr, sprintf(' %d | %d', X,Y), X, Y, 10, [250 248 200]);
Screen('Preference', 'TextAlphaBlending', 0);
else
reset_error = 1;
end
Screen('TextSize', windowPtr, 14);
Screen('Preference', 'TextAlphaBlending', 1);
Screen('TextBackgroundColor', windowPtr, [250 248 200]);
if (size(xErrRight,1) > 10)
newX = 10;
newY = 920;
for i=1:10
[newX,newY] = DrawFormattedText(windowPtr, sprintf(' %7.2f | %7.2f | %7.2f | %7.2f\n', xErrRight(i), yErrRight(i), xErrLeft(i), yErrLeft(i)), newX, newY, 5);
end
end
Screen('TextBackgroundColor', windowPtr, [0 0 0 0]);
Screen('Preference', 'TextAlphaBlending', 0);
Screen('TextSize', windowPtr, 24);
Screen('Flip', windowPtr);
[pressed dum keycode] = KbCheck;
if pressed
if keycode(KbName('escape'))
Datapixx('ShowOverlay');
Datapixx('SetAsleepPictureRequest');
Datapixx('RegWrRd');
Screen('CloseAll');
Datapixx('Close');
% fclose(fileID);
% fclose(fileID2);
break;
end
if keycode(KbName('h'))
visible = 0;
end
if keycode(KbName('u'))
visible = 1;
end
if keycode(KbName('f'))
mfilter = 1;
end
if keycode(KbName('d'))
mfilter = 0;
end
if keycode(KbName('l'))
Datapixx('LoadCalibration');
end
end
end
fclose(fileID);
fclose(fileID2);
end