% FlipScreen.m
%
% This program opens a window using Psychtoolbox 3.0,
% makes the window black, then white, and then closes
% the window again.
%
% written for Psychtoolbox 3 on the PC by YW 3/2023

try
  
  clear all
  
  screens=0; 
  [wPtr,rect]=Screen('OpenWindow',screens, 0, []);
  HideCursor;
  tic
  while toc<5
  end
  black=BlackIndex(wPtr);
  white=WhiteIndex(wPtr);
  Screen('FillRect',wPtr,white);
  Screen(wPtr, 'Flip');
  tic
  while toc<5
  end
  Screen('Close', wPtr);  
  ShowCursor;
catch
  Screen('CloseAll');
  rethrow(lasterror)
end