function [x,y]=drawc(nc);
%function [x,y]=drawc([nc]);
%                     stops drawing when you hit right button on mouse
n=2000;
if nargin==0
           nc=12;
end			  
i=1;
hold on
[x,y,ibutton]=ginput(1);
while (i<n)&(ibutton~=2) 
i=i+1;
[x(i),y(i),ibutton]=ginput(1);
plot(x( (i-1):i),y((i-1):i),['c',int2str(rem(nc+i,15))]);
end
plot(x,y,'c13')

