Moving Oval in Circle using Psychtoolbox in Matlab

Hi.

I have succeeded moving oval diagonally using Psychtoolbox in Matlab.

Here is the code for this.

% Clear the workspace close all; clear all; sca;

% Here we call some default settings for setting up Psychtoolbox PsychDefaultSetup(2);

% Get the screen numbers screens = Screen('Screens'); Screen('Preference', 'VisualDebugLevel', 1);

% Draw to the external screen if avaliable screenNumber = max(screens);

% Define black and white white = WhiteIndex(screenNumber); black = BlackIndex(screenNumber);

% Open an on screen window [window, windowRect] = PsychImaging('OpenWindow', screenNumber, black);

% Get the size of the on screen window [screenXpixels, screenYpixels] = Screen('WindowSize', window);

% Query the frame duration ifi = Screen('GetFlipInterval', window);

% Get the centre coordinate of the window [xCenter, yCenter] = RectCenter(windowRect);

% Make a base Rect of 20 by 20 pixels baseRect = [0 0 20 20]; maxDiameter = max(baseRect) * 1.00;

% Set the color of the rect to red rectColor = [1 0 0];

% Our square will oscilate with a sine wave function to the left and right % of the screen. These are the parameters for the sine wave % See: http://en.wikipedia.org/wiki/Sine_wave amplitude = screenXpixels * 0.25; frequency = 1; angFreq = 2 * pi * frequency; startPhase = 0; time = 0;

% Sync us and get a time stamp vbl = Screen('Flip', window); waitframes = 1;

% Maximum priority level topPriorityLevel = MaxPriority(window); Priority(topPriorityLevel);

% Loop the animation until a key is pressed

while ~KbCheck

    % Position of the square on this frame
    xpos = amplitude*1.875 * cos(angFreq * time + startPhase);
    ypos = amplitude*1 * cos(angFreq * time + startPhase); 

    % Add this position to the screen center coordinate. This is the point
    % we want our square to oscillate around
    squareXpos = xCenter - xpos;
    squareYpos = yCenter + ypos;

    % Center the rectangle on the centre of the screen
    centeredRect = CenterRectOnPointd(baseRect, squareXpos, squareYpos);

    % Draw the rect to the screen

    Screen('FillOval', window, rectColor, centeredRect, maxDiameter);

    % Flip to the screen
    vbl  = Screen('Flip', window, vbl + (waitframes - 0.5) * ifi);

    % Increment the time
    time = time + ifi;

end

% Clear the screen sca; close all; clear all;

From this code, I need to move oval in circle (either clockwise or anticlockwise). Can you please indicate which code to change from this Code Demo.

Further, the reason why I am using these experimental designs (moving oval in circle or diagonal) is to apply it into Eye-tracking (instead of using the Experimental Builder software).

How can I automatically save the Eye Link data while showing this Psychtoolbox stimulus on the computer screen.

Thank You.