DrawLeftArrowToOffScreenDemo.m

function exit_stat = DrawLeftArrowToOffScreenDemo()
exit_stat = 0;


PsychDefaultSetup(2); % assert OpenGL install, unify keys, fix color range
screenNumber = max(Screen('Screens')); % Choose a monitor to display on
[window, winRect] = Screen('OpenWindow', screenNumber, ...
    (2/3)*WhiteIndex(screenNumber)); 

arrowTexture = makeLeftArrowTex(screenNumber, winRect(3)/2, winRect(4)/2, winRect(3)/2 - 100, winRect(4)/2);


Screen('DrawTexture', window, arrowTexture);
Screen('DrawingFinished', window);
Screen('Flip', window);
WaitSecs(2);

sca;
end
  
  
function arrowTexture = makeLeftArrowTex(screenNumber, fromH, fromV, toH, toV)
% make texture of leftward pointing arrow
% open window to which arrow will be drawn. This 'offscreen window'
% can be treated just like a typical texture

  arrowTexture = Screen('OpenOffScreenWindow', screenNumber, ...
    (2/3)*WhiteIndex(screenNumber));
% draw arrow
Screen('DrawLine', arrowTexture, [],...
    fromH, fromV, ...
    toH, toV);
Screen('DrawLine', arrowTexture, [], ...
    toH + 10, toV - 10, ...
    toH, toV);
Screen('DrawLine', arrowTexture, [], ...
    toH + 10, toV + 10, ...
    toH, toV);
end