contourz.m

plot the contour z of an image source code

function handles = contourz(xi,yi,zi,vi,vv,theColor)
%CONTOURZ   3D contour plot on a surface
%   Similar to contour3 but contours are drawn over any surface
%   This function is also used to create clabels.
%
%   Syntax:
%      H = CONTOURZ(X,Y,Z,V,VV,COLOR)
%      H = CONTOURZ('clabel')
%
%   Inputs:
%      XI, YI   2-D arrays
%      ZI       Surface where contours will be drawn, defined at XI,YI
%      VI       2-D array to contour, defined at XI,YI
%      VV       Contour levels or number of contours [ 10 ]
%      COLOR    Color of contours, otherwise a patch is created
%      'clabel' Clabels are created manually as by clabel(cs,'manual')
%               Clabels are done clicking with left mouse button
%               until click with other button
%
%   Outputs:
%      H   handles of lines, patches for contours or handles for labels
%          (marker and text) for clabels
%
%   Comments:
%      This may be useful if you wanna add contours to a
%      surface created by surf(x,y,z,v).
%      Notice that if v = z, is the same as use contour3
%
%   Example:
%      figure
%      [x,y,v] = peaks;
%      z=-(x.^2+y.^2);
%      surf(x,y,z,'facecolor','none','edgealpha',.1)
%      hold on
%      contourz(x,y,z,v);
%      view(2)
%      contourz('clabel');
%      view(3)
%
%   MMA 8-2004, [e-mail]

%   Department of physics
%   University of Aveiro

handles = [];

% --------------------------------------------------------------------
% clabel
% --------------------------------------------------------------------
if isequal(xi,'clabel')
  is_hold = ishold;
  hold on
  vw = view;
  %view(2);
  h=[];
  while 1
    [x,y,mouse] = ginput(1);
    if mouse ~= 1
      break
    end
    tag = get(gco,'tag');
    if isequal(tag,'contourz')
      % get closest point:
      xdata = get(gco,'xdata');
      ydata = get(gco,'ydata');
      zdata = get(gco,'zdata');
      dist = (xdata-x).^2 + (ydata-y).^2;
      i=find(dist == min(dist));

      level = get(gco,'userdata');  
      p=plot3(xdata(i),ydata(i),zdata(i),'r+');
      t=text(xdata(i),ydata(i),zdata(i),num2str(level), ...
        'HorizontalAlignment','left');

      h=[h;p;t];
    end
  end
  view(vw)
  handles = h;

  if ~is_hold
    hold off
  end

  return
end

% --------------------------------------------------------------------
% contour
% --------------------------------------------------------------------
if nargin < 4
  disp('