[ci] fix failed ci demo, speed up vol2surf significantly

Author: fangq

binsurface.m

@@ -73,7 +73,7 @@
 % populate all the triangles
 xy = newdim(1) * newdim(2);
 
-if (nargin == 1 || nface == 3)  % create triangular elements
+if (nargin == 1 || abs(nface) == 3)  % create triangular elements
     elem = [id1 id1 + newdim(1) id1 + newdim(1) + xy; id1 id1 + newdim(1) + xy id1 + xy];
     elem = [elem; id2 id2 + 1 id2 + 1 + xy; id2 id2 + 1 + xy id2 + xy];
     elem = [elem; id3 id3 + 1 id3 + 1 + newdim(1); id3 id3 + 1 + newdim(1) id3 + newdim(1)];

test/run_iso2mesh_test.m

@@ -101,7 +101,7 @@ function run_iso2mesh_test(tests)
 
     [no, el, fc] = v2m(im, 0.5, 0.03, 10);
     test_iso2mesh('v2m face', @savejson, round_to_digits(sum(elemvolume(no, fc(:, 1:3))), 2), '[5.01]');
-    test_iso2mesh('v2m elem', @savejson, round_to_digits(sum(elemvolume(no, el(:, 1:4))), 4), '[0.8786]');
+    test_iso2mesh('v2m elem', @savejson, round_to_digits(sum(elemvolume(no, el(:, 1:4))), 4), '[0.8787]');
 end
 
 %%

vol2surf.m

@@ -89,12 +89,7 @@
         else
             levelmask = int8(newimg >= isovalues(i));
         end
-        [isoct, octver] = isoctavemesh;
-        if (~isoct || sscanf(octver, '%d') > 5)
-            [levelno, levelel] = binsurface(levelmask, 'iso');
-        else
-            [levelno, levelel] = binsurface(levelmask);
-        end
+        [levelno, levelel] = binsurface(levelmask, -3);
         if (~isempty(levelel))
             if (isstruct(opt) && isfield(opt, 'autoregion'))
                 if (opt.autoregion)
@@ -146,7 +141,7 @@
             f0 = removeisolatedsurf(v0, f0, 3);
 
             if (dofix)
-                [v0, f0] = meshcheckrepair(v0, f0);
+                [v0, f0] = meshcheckrepair(v0, f0, 'meshfix');
             end
 
         elseif (nargin < 7 || strcmp(method, 'cgalsurf') || strcmp(method, 'cgalpoly'))