/usr/share/psychtoolbox-3/PsychDemos/DriftDemo.m is in psychtoolbox-3-common 3.0.11.20131230.dfsg1-1build1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 | function DriftDemo
% DriftDemo
% ___________________________________________________________________
%
% Display an animated grating using the new Screen('DrawTexture') command.
% In Psychtoolbox-3 Screen('DrawTexture') replaces
% Screen('CopyWindow').
%
% This is a very simple, bare bones demo on how to do frame animation. For
% much more efficient ways to draw gratings and gabors, have a look at
% DriftDemo2, DriftDemo3, DriftDemo4, ProceduralGaborDemo, GarboriumDemo,
% ProceduralGarboriumDemo and DriftWaitDemo.
%
% CopyWindow vs. DrawTexture:
%
% In the OS 9 Psychtoolbox, Screen ('CopyWindow") was used for all
% time-critical display of images, in particular for display of the movie
% frames in animated stimuli. In contrast, Screen('DrawTexture') should not
% be used for display of all graphic elements, but only for display of
% MATLAB matrices. For all other graphical elements, such as lines, rectangles,
% and ovals we recommend that these be drawn directly to the display
% window during the animation rather than rendered to offscreen windows
% prior to the animation.
% _________________________________________________________________________
%
% see also: PsychDemos, MovieDemo
% HISTORY
% 6/28/04 awi Adapted from Denis Pelli's DriftDemo.m for OS 9
% 7/18/04 awi Added Priority call. Fixed.
% 9/8/04 awi Added Try/Catch, cosmetic changes to comments and see also.
% 4/23/05 mk Added Priority(0) in catch section, moved Screen('OpenWindow')
% before first call to Screen('MakeTexture') in
% preparation of future improvements to 'MakeTexture'.
% 2/28/09 mk Smallish refinements, cleanups, updated comments.
try
% This script calls Psychtoolbox commands available only in OpenGL-based
% versions of the Psychtoolbox. (So far, the OS X Psychtoolbox is the
% only OpenGL-base Psychtoolbox.) The Psychtoolbox command AssertPsychOpenGL will issue
% an error message if someone tries to execute this script on a computer without
% an OpenGL Psychtoolbox
AssertOpenGL;
% Get the list of screens and choose the one with the highest screen number.
% Screen 0 is, by definition, the display with the menu bar. Often when
% two monitors are connected the one without the menu bar is used as
% the stimulus display. Chosing the display with the highest dislay number is
% a best guess about where you want the stimulus displayed.
screens=Screen('Screens');
screenNumber=max(screens);
% Find the color values which correspond to white and black: Usually
% black is always 0 and white 255, but this rule is not true if one of
% the high precision framebuffer modes is enabled via the
% PsychImaging() commmand, so we query the true values via the
% functions WhiteIndex and BlackIndex:
white=WhiteIndex(screenNumber);
black=BlackIndex(screenNumber);
% Round gray to integral number, to avoid roundoff artifacts with some
% graphics cards:
gray=round((white+black)/2);
% This makes sure that on floating point framebuffers we still get a
% well defined gray. It isn't strictly neccessary in this demo:
if gray == white
gray=white / 2;
end
% Contrast 'inc'rement range for given white and gray values:
inc=white-gray;
% Open a double buffered fullscreen window and select a gray background
% color:
w=Screen('OpenWindow',screenNumber, gray);
% Compute each frame of the movie and convert the those frames, stored in
% MATLAB matices, into Psychtoolbox OpenGL textures using 'MakeTexture';
numFrames=12; % temporal period, in frames, of the drifting grating
for i=1:numFrames
phase=(i/numFrames)*2*pi;
% grating
[x,y]=meshgrid(-300:300,-300:300);
angle=30*pi/180; % 30 deg orientation.
f=0.05*2*pi; % cycles/pixel
a=cos(angle)*f;
b=sin(angle)*f;
m=exp(-((x/90).^2)-((y/90).^2)).*sin(a*x+b*y+phase);
tex(i)=Screen('MakeTexture', w, gray+inc*m); %#ok<AGROW>
end
% Run the movie animation for a fixed period.
movieDurationSecs=5;
frameRate=Screen('FrameRate',screenNumber);
% If MacOSX does not know the frame rate the 'FrameRate' will return 0.
% That usually means we run on a flat panel with 60 Hz fixed refresh
% rate:
if frameRate == 0
frameRate=60;
end
% Convert movieDuration in seconds to duration in frames to draw:
movieDurationFrames=round(movieDurationSecs * frameRate);
movieFrameIndices=mod(0:(movieDurationFrames-1), numFrames) + 1;
% Use realtime priority for better timing precision:
priorityLevel=MaxPriority(w);
Priority(priorityLevel);
% Animation loop:
for i=1:movieDurationFrames
% Draw image:
Screen('DrawTexture', w, tex(movieFrameIndices(i)));
% Show it at next display vertical retrace. Please check DriftDemo2
% and later, as well as DriftWaitDemo for much better approaches to
% guarantee a robust and constant animation display timing! This is
% very basic and not best practice!
Screen('Flip', w);
end
Priority(0);
% Close all textures. This is not strictly needed, as
% Screen('CloseAll') would do it anyway. However, it avoids warnings by
% Psychtoolbox about unclosed textures. The warnings trigger if more
% than 10 textures are open at invocation of Screen('CloseAll') and we
% have 12 textues here:
Screen('Close');
% Close window:
Screen('CloseAll');
catch
%this "catch" section executes in case of an error in the "try" section
%above. Importantly, it closes the onscreen window if its open.
Screen('CloseAll');
Priority(0);
psychrethrow(psychlasterror);
end %try..catch..
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