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% GaborArrayDemo
% Written by Peter Scarfe
PsychDefaultSetup(2);
% Screen Number
screenNumber = max(Screen('Screens'));
% Define black, white and grey
white = WhiteIndex(screenNumber);
grey = GrayIndex(screenNumber);
black = BlackIndex(screenNumber);
% Open the screen
PsychImaging('PrepareConfiguration');
PsychImaging('AddTask', 'General', 'FloatingPoint32Bit');
[window, windowRect] = PsychImaging('OpenWindow', screenNumber, grey);
% Query the frame duration
ifi = Screen('GetFlipInterval', window);
% Maximum priority level
topPriorityLevel = MaxPriority(window);
% Get the centre coordinate of the window
[xCenter, yCenter] = RectCenter(windowRect);
%--------------------
% Gabor information
%--------------------
% Dimensions
gaborDimPix = 55;
% Sigma of Gaussian
sigma = gaborDimPix / 6;
% Obvious Parameters
orientation = 90;
contrast = 0.5;
aspectRatio = 1.0;
% Spatial Frequency (Cycles Per Pixel)
% One Cycle = Grey-Black-Grey-White-Grey i.e. One Black and One White Lobe
numCycles = 3;
freq = numCycles / gaborDimPix;
% Build a procedural gabor texture
gabortex = CreateProceduralGabor(window, gaborDimPix, gaborDimPix, [], [0.5 0.5 0.5 0.0], 1, 0.5);
% Positions of the Gabors
dim = 8;
[x, y] = meshgrid(-dim:dim, -dim:dim);
% Calculate the distance in "Gabor numbers" of each gabor from the center
% of the array
dist = sqrt(x.^2 + y.^2);
% Cut out an inner annulus
innerDist = 3.5;
x(dist <= innerDist) = nan;
y(dist <= innerDist) = nan;
% Cut out an outer annulus
outerDist = 10;
x(dist >= outerDist) = nan;
y(dist >= outerDist) = nan;
% Select only the finite values
x = x(isfinite(x));
y = y(isfinite(y));
% Center the annulus coordinates in the centre of the screen
xPos = x .* gaborDimPix + xCenter;
yPos = y .* gaborDimPix + yCenter;
% Count how many Gabors there are
nGabors = numel(xPos);
% Make the destination rectangles for all the Gabors in the array
baseRect = [0 0 gaborDimPix gaborDimPix];
allRects = nan(4, nGabors);
for i = 1:nGabors
allRects(:, i) = CenterRectOnPointd(baseRect, xPos(i), yPos(i));
end
% Drift speed for the 2D global motion
degPerSec = 360 * 4;
degPerFrame = degPerSec * ifi;
% Randomise the Gabor orientations and determine the drift speeds of each gabor.
% This is given by multiplying the global motion speed by the cosine
% difference between the global motion direction and the global motion.
% Here the global motion direction is 0. So it is just the cosine of the
% angle we use. We re-orientate the array when drawing
gaborAngles = rand(1, nGabors) .* 180 - 90;
degPerFrameGabors = cosd(gaborAngles) .* degPerFrame;
% Randomise the phase of the Gabors and make a properties matrix. We could
% if we want have each Gabor with different properties in all dimensions.
% Not just orientation and drift rate as we are doing here.
% This is the power of using procedural textures
phaseLine = rand(1, nGabors) .* 360;
propertiesMat = repmat([NaN, freq, sigma, contrast, aspectRatio, 0, 0, 0], nGabors, 1);
propertiesMat(:, 1) = phaseLine';
% Perform initial flip to gray background and sync us to the retrace:
vbl = Screen('Flip', window);
% Numer of frames to wait before re-drawing
waitframes = 1;
% Animation loop
while ~KbCheck
% Set the right blend function for drawing the gabors
Screen('BlendFunction', window, 'GL_ONE', 'GL_ZERO');
% Batch draw all of the Gabors to screen
Screen('DrawTextures', window, gabortex, [], allRects, gaborAngles - 90, [], [], [], [],...
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 our drawing to the screen
vbl = Screen('Flip', window, vbl + (waitframes - 0.5) * ifi);
% Increment the phase of our Gabors
phaseLine = phaseLine + degPerFrameGabors;
propertiesMat(:, 1) = phaseLine';
end
% Wait for keyboard press
KbStrokeWait;
% Clean up
sca;
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