How to display Gabor stimuli toward left of screen instead of center

Programming Help
1

if true
% 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);
grey = white / 2;
% Skip sync tests for demo purposes only
Screen(‘Preference’, ‘SkipSyncTests’, 2);
% Open the screen
[window, windowRect] = PsychImaging(‘OpenWindow’, screenNumber, grey, [], 32, 2,…
[], [], kPsychNeed32BPCFloat);
% Dimension of the region where will draw the Gabor in pixels
gaborDimPix = windowRect(4) / 2;
% 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);
% Randomise the phase of the Gabors and make a properties matrix.
propertiesMat = [phase, freq, sigma, contrast, aspectRatio, 0, 0, 0];
% Draw the Gabor. By default PTB will draw this in the center of the screen
% for us.
Screen(‘DrawTextures’, window, gabortex, [], [], orientation, [], [], [], [],…
kPsychDontDoRotation, propertiesMat’);
% Flip to the screen
Screen(‘Flip’, window);
% Wait for a button press to exit

KbWait;

% Clear screen
sca;
end

I have the code above which displays a gabor patch at the center of the screen. How can I change the code so I can display the gabor stimuli towards the left of the screen instead of the default center of the screen?

2

If you read the documentation for DrawTextures:

Screen DrawTextures?

Screen('DrawTextures', windowPointer, texturePointer(s) [, sourceRect(s)] [, destinationRect(s)] [, rotationAngle(s)] [, filterMode(s)] [, globalAlpha(s)] [, modulateColor(s)] [, textureShader] [, specialFlags] [, auxParameters]);

You will see the 4th parameter is destinationRect(s) which is a PTB drawing position defined as a [rect]angle of the order: [left,top,right,bottom]. Type help PsychRects for more info and functions for rect management…