How to draw an arrow or triangle

Question

Brett 2012-11-14

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https://ww2.mathworks.cn/matlabcentral/answers/53641-how-to-draw-an-arrow-or-triangle

回答： Sanjay Manohar 2017-2-14

Hello Matlab community, I am trying to draw an arrow. I am using Psychtoolbox and there doesn't seem to be a specific command for arrows or triangles. I know how to draw a line:

 line = [X-3,Y-40,X+3,Y+40];
 Screen('FillRect',window,[200,200,200], line');

So if someone knows the code to draw a triangle I can merge it with the code for a line to draw an arrow. Any help would be greatly appreciated.

Thanks, Brett

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Answer 1

Sanjay Manohar 2017-2-14

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在 MATLAB Online 中打开

This is not a MATLAB question. But for completeness, the answer should be

    % create a triangle
    head   = [ 100, 100 ]; % coordinates of head
    width  = 10;           % width of arrow head
    points = [ head-[width,0]         % left corner
               head+[width,0]         % right corner
               head+[0,width] ];      % vertex
    Screen('FillPoly', window,[200,200,200], points);

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Answer 2

Image Analyst 2012-11-14

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Are you aware of the annotation() function?

annotation('line',x,y)
annotation('arrow',x,y)
annotation('doublearrow',x,y)
annotation('textarrow',x,y)
annotation('textbox',[x y w h])
annotation('ellipse',[x y w h])
annotation('rectangle',[x y w h])
annotation(figure_handle,...)

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sina farahi 2014-4-9

annotation('arrow',x,y) doesn't work

Image Analyst 2014-4-9

编辑：Image Analyst 2014-4-9

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At all? Or just with some figure created by the Psychtoolbox (which is not a Mathworks product and I don't have)? Does this draw an arrow for you:

plot(1:10, 'LineWidth', 2);
grid on;
annotation('arrow', [.21, .5], [.85, .5], 'LineWidth', 2);

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Answer 3

sina farahi 2014-4-9

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https://ww2.mathworks.cn/matlabcentral/answers/53641-how-to-draw-an-arrow-or-triangle#answer_132827

Arrow.m

usage: Arrow(dot,vector); note: This function draw an arrow (head lines have pi/6 angle and the length of l/5) example: Arrow([10;11;12],[0.2;20;25]);