% Plot a 2D shape -- calls MySpline<BR>
% function [X,Y] = MySpline(x,y,n);<BR>
function [X,Y] = Plot2D(f1,f2,res);
<P>
% Create a user-defined spline<BR>
if isempty(f1) & isempty(f2)<BR>
   cla;<BR>
   axis on;<BR>
   axis([-1 1 -1 1]);<BR>
   axis square;<BR>
   b = 1;<BR>
   i = 0;
<P>
   % Read mouse clicks every time the main button is pressed<BR>
   while (b == 1)<BR>
      i = i + 1;<BR>
      [x(i),y(i),b] = ginput(1);<BR>
      plot(x(i),y(i),'o');<BR>
      axis([-1 1 -1 1]);<BR>
      axis square;<BR>
      hold on;<BR>
   end
<P>
   % Plot a spline fit to the chosen points<BR>
   [X,Y] = MySpline(x,y,res);<BR>
   cla;<BR>
   plot(X,Y);<BR>
   hold off;
<P>
% Plot the parametric shape defined by f1, f2<BR>
elseif not(isempty(f1)) & not(isempty(f2))<BR>
   t = linspace(0,2*pi,res);<BR>
   X = eval(f1);<BR>
   Y = eval(f2);<BR>
   plot(X,Y);<BR>
   axis square;
<P>
% User is in the process of changing equations<BR>
else<BR>
   X = '';<BR>
   Y = '';<BR>
end