addContourLines(orders,mi,ma,values)

function h = addContourLines(orders,mi,ma,values)

% Calculate score surface.
xlim = get(gca,'xlim');
ylim = get(gca,'ylim');
[xx,yy] = meshgrid(linspace(xlim(1),xlim(2),200),linspace(ylim(1),ylim(2),200));
zz = final(reverse(yy,orders,mi,ma),xx);

% Calculate contour values.
if nargin < 4
    nLines = 20;
    values = final(reverse(logspace(log10(ylim(1)),log10(ylim(2)),nLines),orders,mi,ma),zeros(1,nLines));
end

% Add contour lines to the plot
[null,h] = contour(xx,yy,zz,values);

% Send to back.
kids = get(gca,'Children');
kids(kids == h) = [];
kids(end+1) = h;
set(gca,'Children',kids)

% Color.
lightGray = ones(3,1)*.7;
set(h,'EdgeColor',lightGray)