How to create randomly distributed triangles

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Ron 2020-8-26

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编辑： Rik 2020-10-3

I need to create a moving visual display consisting of 500 randomly distributed white triangles (3.4 × 3.4 × 3 cm) on a black background. The frame rate of the visual display needs to be 60 Hz, triangles move in fore-aft direction. Could you please help me figure this out? Thank you.

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Rik 2020-9-2

You can write videos with Matlab. I have never done that before, so I would have to do the same as you: google 'write video Matlab'. You can produce each frame as an image and write it to a video file.

Syncing with an external device might be tricky though. That depends mostly on how that sync should work.

Ron 2020-9-3

Thank you, Rik. I'll look into making a video. And then use a DAQ to connect with other device.

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Rik 2020-9-2

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Slightly editing your code gets me to a max framerate of just under 200. Results will vary for different systems.

w = 3 ;
ar=0.866; % Aspect ratio for equilateral triangle
h=ar*w;%height of triangle
p=[];origins=cell(1,10);
figure(1),clf(1)
for k=1:10
    x=[0 w w/2];%x coordinates of vertices
    y=[0 0 h];%y coordinates of vertices
    x=x+15*rand-5;y=y+15*rand-5;%add random
    p(k)= patch(x,y,'white'); %#ok<SAGROW> plotting triangle in white color
    origins{k}=[mean(x) mean(y) 0];%store explicitly to prevent having to retrieve it from an object
end
set(gca,'Color','k','xticklabel',[],'yticklabel',[])%setting background black and removing labels
daspect([1 1 1]);%equal data unit length along x and y axis
xlim([-5 15]),ylim([-5 15])
rotation_per_frame_in_deg=0.8;
target_fps=60;
frametime=1/target_fps;
h_tic=tic;
for n=1:60%do 60 frames
    tic
    for k=1:numel(p)
        rotate(p(k),[0 0 1],rotation_per_frame_in_deg,origins{k})
    end
    drawnow
    pause(frametime-toc)%comment this line to see the max framerate
end
t=toc(h_tic);
fprintf('the fps was %.1f Hz\n',n/t)