MATLAB: How to connect plot points with lines using ginput

ginput

I am trying to program a function called draw_constellation. By using ginput,the user would click on the figure and a plot point will appear. Any subsequent plot points would be connected with a line. My problem is connecting the third point with the second point and so on. Currently, the code I have only plots the first two points with a line.

Here is what I currently have:

function[] = draw_constellations
axis([0 100 0 100]);
set(gcf,'color','k');
set(gca,'color','k');
axis square;
hold on;
while 1 
    [x,y,button] = ginput(1);
      if button == 113
        break;             
      else
          hold on
          plot(x,y,'w*')
      end
      [xn,yn,button] = ginput(1);
      plot(xn,yn,'w*');
      plot([x,xn],[y,yn],'w');
end

Best Answer

The attached function should show you how to do what you need, though you will have to modify it for your purpose.

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MATLAB: Question about mouse click on figure

This code snippet should get you started:

 button = 1;
 getpt  = 1;
 [x,y,button] = ginput(1);
 XY           = [x y];
 while (getpt == 1)
    if (button == 1) % draw line for left mouse click
        [xn,yn,button] = ginput(1);
        XY = [XY; xn yn];
        hold on
        plot([x; xn],[y; yn])
        x = xn; y = yn;
    end
    if (button == 3) % clear lines for right mouse click
        children = get(gca, 'children');
        delete(children);
        getpt = 0;
    end
 end

MATLAB: Write a function called draw_constellations that takes no input arguments and returns no output arguments. Instead, it obtains its input via the function ginput.

Create the line object prior to the while-loop using NaN values for the x and y data. Then update the x and y data within the loop.

h = plot(nan, nan, 'r-o');  % Set the line properties here, too
while 1
    
    . . .
    
    a = 1; 
    [x y button] = ginput(a);
    set(h,'XData', [h.XData, x], 'YData', [h.YData, y])  % Update line coordinates
    
    . . .
    
end
h.XData(1) = [];  % remove initial NaN

h.YData(1) = [];  % remove initial NaN

Best Answer

Related Solutions

MATLAB: Question about mouse click on figure

MATLAB: Write a function called draw_constellations that takes no input arguments and returns no output arguments. Instead, it obtains its input via the function ginput.

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