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

% Setup PTB with some default values
PsychDefaultSetup(2);

% Set the screen number to the external secondary monitor if there is one
% connected
screenNumber = max(Screen('Screens'));

% Define black, white and grey
white = WhiteIndex(screenNumber);
black = BlackIndex(screenNumber);
grey = white / 2;

% % Open the screen
[window, windowRect] = PsychImaging('OpenWindow', screenNumber, grey, [], 32, 2,...
    [], [],  kPsychNeed32BPCFloat);

% Get the vertical refresh rate of the monitor
ifi = Screen('GetFlipInterval', window);

% Set maximum priority level
topPriorityLevel = MaxPriority(window);
Priority(topPriorityLevel);

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


%--------------------
% Gabor information
%--------------------

% Dimension of the region where will draw the Gabors in pixels
gaborDimPix = windowRect(4) / 4;

% Sigma of Gaussian
sigma = gaborDimPix / 7;

% Obvious Parameters
orientation = 0;
contrast = 0.8;
aspectRatio = 1.0;
phase = 0;

% Spatial Frequency (Cycles Per Pixel)
% One Cycle = Grey-Black-Grey-White-Grey i.e. One Black and One White Lobe
numCycles = 5;
freq = numCycles / gaborDimPix;

% Build a procedural gabor texture (Note: to get a "standard" Gabor patch
% we set a grey background offset, disable normalisation, and set a
% pre-contrast multiplier of 0.5).
backgroundOffset = [0.5 0.5 0.5 0.0];
disableNorm = 1;
preContrastMultiplier = 0.5;
gabortex = CreateProceduralGabor(window, gaborDimPix, gaborDimPix, [],...
    backgroundOffset, disableNorm, preContrastMultiplier);

% Number of Gabors
numGabors = 2;

% Randomise the phase of the Gabors and make a properties matrix
propertiesMat = repmat([phase, freq, sigma, contrast, aspectRatio, 0, 0, 0], numGabors, 1);
propertiesMat(:, 1) = rand(1, 2) * 360;

% Positions of the gabors
gabShifts = [0.25 0.75] * windowRect(4);
gaborsRects = nan(4, 2);
for i = 1:numGabors
    gaborsRects(:, i) = CenterRectOnPointd([0 0 gaborDimPix gaborDimPix], windowRect(3) / 2, gabShifts(i));
end

%------------------------------------------
%    Draw stuff - button press to exit
%------------------------------------------

% FLip to the vertical retrace rate
vbl = Screen('Flip', window);

% We will update the stimulus on each frame
waitframes = 1;

% We choose an arbitary value at which our Gabor will drift
phasePerFrame = 4 * pi;

while ~KbCheck

    % Set the right blend function for drawing the gabors
    Screen('BlendFunction', window, 'GL_ONE', 'GL_ZERO');

    % Draw the Gabor. By default PTB will draw this in the center of the screen
    % for us.
    Screen('DrawTextures', window, gabortex, [], gaborsRects, orientation, [], [], [], [],...
        kPsychDontDoRotation, propertiesMat');

    % Change the blend function to draw an antialiased fixation point
    % in the centre of the array
    Screen('BlendFunction', window, 'GL_SRC_ALPHA', 'GL_ONE_MINUS_SRC_ALPHA');

    % Draw the fixation point
    Screen('DrawDots', window, [xCenter; yCenter], 10, black, [], 2);

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

    % Update the phase element of the properties matrix (we could if we
    % want update any or all of the properties on each frame. Here the
    % Gabor will drift to the left.
    propertiesMat(:, 1) = propertiesMat(:, 1) + ([-1; 1] * phasePerFrame);

end

% Clear screen
sca;

Published with MATLAB® R2022b