%
% NUMSCAL label scalar (Q) values at x,y locations on current axes.
%
% Input:  x  - x-coordinate array
%         y  - y-coordinate array
%         Q  - scalar (1-D vector)
%         ps - point size for screen text numbers (optional, def=8)
%
%         NOTES: 1) NUMSCAL overlays existing plots regardless of
%                   the state of hold
%                2) NUMSCAL determines if the current density of nodes
%                   is too high to make the node numbers readable.
%                   If node density is too high, NUMSCAL displays 
%                   a warning box asking the user if NUMSCAL
%                   should plot the numbers anyway.
%
% Call as: >> numscal(x,y,Q,ps);
%
% Written by : Brian O. Blanton
%
function h=numscal(x,y,Q,ps)

% DEFINE ERROR STRINGS
err1=['Not enough input arguments; need atleast x,y'];
err2=['Lengths of x,y must be the same'];
err3=['Lengths of Q must be the same as x,y'];
warn1=str2mat('The current axes is too dense for the  ',...
       'scalar values to be readable.  CONTINUE?'); 
       
% check arguments
if nargin < 3 
   error(err1);
end

% define pointsize if not input
if exist('ps')~=1,ps=8;,end

% check input arguments length
if length(x)~=length(y) 
   error(err2);
end
if length(x)~=length(Q) 
   error(err3);
end

% compute offset as 2% of each axis range
X=get(gca,'Xlim');
Y=get(gca,'YLim');
off=(X(2)-X(1))/50;
off=0;

% get indices of nodes within viewing window defined by X,Y
filt=find(x>=X(1)&x<=X(2)&y>=Y(1)&y<=Y(2));

% determine if viewing window is zoomed-in
% enough for node numbers to be meaningful
oldunits=get(gca,'Units'); 
set(gca,'Units','Points'); 
rect=get(gca,'Position');        % get viewing window width in 
set(gca,'Units',oldunits);       % point units (1/72 inches)
xr=rect(3)-rect(1);
yr=rect(4)-rect(2);;
xden=xr/sqrt(length(filt));
yden=yr/sqrt(length(filt));
den=sqrt(xden*xden+yden*yden);
if den < 5*ps
   click=questdlg(warn1,'yes','no');
   if strcmp(click,'no'),return,end
end

% label only those nodes that lie within viewing window.
for i=1:length(filt)
    h(i)=text(x(filt(i))+off,y(filt(i))+off,num2str(Q(filt(i)),6),...
         'FontSize',ps,...
         'HorizontalAlignment','left',...
         'VerticalAlignment','middle',...
         'Tag','Node Scalar Value');
end
%
%        Brian O. Blanton
%        Curr. in Marine Science
%        15-1A Venable Hall
%        CB# 3300
%        Uni. of North Carolina
%        Chapel Hill, NC
%                 27599-3300
%
%        919-962-4466
%        blanton@marine.unc.edu
%