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function ProceduralSquareWaveDemo(benchmark)
% ProceduralSquareWaveDemo([benchmark=0])
%
% This demo demonstrates fast drawing of apertured square wave gratings
% using procedural shaders. It only works on hardware with support for the GLSL
% shading language, vertex- and fragment-shaders.
% History:
% 12/12/2017 modified from ProceduralGaborDemo.m (Ian Andolina).
% Default to mode 0 - Just a nice demo.
if nargin < 1
benchmark = 0;
end
% Setup defaults and unit color range:
PsychDefaultSetup(2);
% Disable synctests for this quick demo:
oldSyncLevel = Screen('Preference', 'SkipSyncTests', 2);
% Choose screen with maximum id - the secondary display:
screenid = max(Screen('Screens'));
% Open a window
PsychImaging('PrepareConfiguration');
win = PsychImaging('OpenWindow', screenid, 0.5);
% Initial stimulus params for the grating:
res = 600;
phase = 0;
freq = .04;
tilt = 225;
contrast = 0.5;
% Build a procedural gabor texture for a grating with a support of tw x th
% pixels, and a RGB color offset of 0.5 -- a 50% gray.
squarewavetex = CreateProceduralSquareWaveGrating(win, res, res, [.5 .5 .5 0], res/2);
% Draw the grating once, just to make sure the gfx-hardware is ready for the
% benchmark run below and doesn't do one time setup work inside the
% benchmark loop:
Screen('DrawTexture', win, squarewavetex, [], [], tilt, [], [], [], [], [], [phase, freq, contrast, 0]);
% Perform initial flip to gray background and sync us to the retrace:
vbl = Screen('Flip', win);
tstart = vbl;
count = 0;
% Animation loop
while GetSecs < tstart + 5
count = count + 1;
% update values:
phase = phase + 5;
% Draw the grating:
Screen('DrawTexture', win, squarewavetex, [], [], tilt, [], [], [], [], [], [phase, freq, contrast, 0]);
if benchmark > 0
% Go as fast as you can without any sync to retrace and without
% clearing the backbuffer -- we want to measure gabor drawing speed,
% not how fast the display is going etc.
Screen('Flip', win, 0, 2, 2);
else
% Go at normal refresh rate for good looking gabors:
Screen('Flip', win);
end
end
% A final synced flip, so we can be sure all drawing is finished when we
% reach this point; print some stats
tend = Screen('Flip', win);
avgfps = count / (tend - tstart);
fprintf('\nPresented a total of %i frames at ~%.2g FPS...\n',count,avgfps);
% Close window, release all ressources:
sca
% Restore old settings for sync-tests:
Screen('Preference', 'SkipSyncTests', oldSyncLevel);
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