function [layer] = picklayer(width,height)
% Pick an arbitrary interface.
% Only points in ascending order of X are input.
% Pressing the 'Enter' key terminates the sequence of points.
% width and hight are the dimensions of the area,
% layer is array of picked points.

position = 0;
hold on;
axis([0,width,0,height]);   % plot range
set(gca,'YDir','reverse');  % reverse the vertical axis

pnt = ginput(1);    % read a point from user input

while (length(pnt) > 0 )
    
    % accept only increasing X
    if ( position == 0 || pnt(1) > layer(position,1) )
        
        position = position +1;
        
        layer(position,1) = pnt(1);
        layer(position,2) = pnt(2);
    
        plot(pnt(1),pnt(2),'bo');

        if (position >=2) 
            plot(layer( (position-1):position,1),layer((position-1):position,2),'r-');
        end;
            
    end;
    
    pnt = ginput(1);
end;