MATLAB: How to plot graph using ginput

graphgraphic inputplot

Hi friends i want to plot a graph between two graphic input, i did it but i want to make it as my input should be visible before plotting.
This is my code..
axis([0 100 0 100]);
hold on
nodes = 2;
PauseTime = 0.05; 
[x,y] = ginput(nodes);
plot(x,y,'--ys','LineWidth',2,'MarkerEdgeColor','b','MarkerFaceColor','b', 'MarkerSize',4);
please help me….

Best Answer

To do what you want would require using callback functions. See this video here to understand how it works: https://blogs.mathworks.com/videos/2008/05/27/advanced-matlab-capture-mouse-movement/
To summon this function, do:
plotLines(5) %for 5 points, 4 lines
The function is below. You have to modify this based on what you want to accomplish with drawing lines. Play around with the callback functions: startLine, stopLine, dragLine.
function plotLines(nodes)
axis([0 100 0 100]);
set(gca, 'xlim', [0 100], 'ylim', [0 100]);
hold on;
%nodes = 2; %It's now the function input
PauseTime = 0.05; %You can use drawnow instead of pause to refresh plots.
set(gcf, 'WindowButtonDownFcn', @startLine);
set(gcf, 'WindowButtonUpFcn', @stopLine);
      function startLine(varargin)
          pt = get(gca, 'currentpoint');
          if isempty(findobj(gca, 'type', 'line'))
              plot(gca, [pt(1,1), pt(1,1)], [pt(1,2), pt(1,2)], '--ys', 'LineWidth',2, 'MarkerEdgeColor','b', 'MarkerFaceColor','b', 'MarkerSize',4);
          else
              Lx = findobj(gca, 'type', 'line');
              Xdata = get(Lx, 'Xdata');
              Ydata = get(Lx, 'Ydata');
              if length(Xdata) > nodes-1; return; end %Edit this depending on your definition of "node".
              Xdata(end+1) = pt(1,1);
              Ydata(end+1) = pt(1,2);
              set(Lx, 'Xdata', Xdata, 'Ydata', Ydata);   
          end
          set(gcf, 'WindowButtonMotion', @dragLine)
      end
      function dragLine(varargin)
          pt = get(gca, 'currentpoint');
          Lx = findobj(gca, 'type', 'line');
          Xdata = get(Lx, 'Xdata');
          Ydata = get(Lx, 'Ydata');
          Xdata(end) = pt(1,1);
          Ydata(end) = pt(1,2);
          set(Lx, 'Xdata', Xdata, 'Ydata', Ydata);
      end
      function stopLine(varargin)
          set(gcf, 'WindowButtonMotion', '');
      end
  end
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