merge patch from Jose Paulo Moitinho de Almeida for...

merge patch from Jose Paulo Moitinho de Almeida for AlternateRight/AlternateLeft transfinite options

Geo/GFace.h

@@ -286,7 +286,7 @@ class GFace : public GEntity
     // corners of the transfinite interpolation
     std::vector<GVertex*> corners;
     // all diagonals of the triangulation are left (-1), right (1) or
-    // alternated (0)
+    // alternated starting at right (2) or left (-2)
     int transfiniteArrangement;
     // do we smooth (transfinite) mesh? (<0 to use default smoothing)
     int transfiniteSmoothing;

Geo/Geo.h

@@ -148,7 +148,7 @@ class Surface{
   char Visible;
   int Method;
   int Recombine;
-  int Recombine_Dir; // -1 is left, +1 is right, 0 is alternated
+  int Recombine_Dir; // -1 is left, +1 is right, -2/2 is alternated left/right
   double RecombineAngle;
   int TransfiniteSmoothing;
   List_T *Generatrices;

Mesh/meshGFaceTransfinite.cpp

@@ -423,9 +423,13 @@ int MeshTransfiniteSurface(GFace *gf)
         if(CTX::instance()->mesh.recombineAll || gf->meshAttributes.recombine)
           gf->quadrangles.push_back(new MQuadrangle(v1, v2, v3, v4));
         else if(gf->meshAttributes.transfiniteArrangement == 1 ||
-                (gf->meshAttributes.transfiniteArrangement == 0 &&
+                (gf->meshAttributes.transfiniteArrangement == 2 &&
                  ((i % 2 == 0 && j % 2 == 1) ||
-                  (i % 2 == 1 && j % 2 == 0)))){
+                  (i % 2 == 1 && j % 2 == 0))) ||
+		(gf->meshAttributes.transfiniteArrangement == -2 &&
+                 ((i % 2 == 0 && j % 2 == 0) ||
+                  (i % 2 == 1 && j % 2 == 1)))
+		){
           gf->triangles.push_back(new MTriangle(v1, v2, v3));
           gf->triangles.push_back(new MTriangle(v3, v4, v1));
         }
@@ -452,9 +456,13 @@ int MeshTransfiniteSurface(GFace *gf)
         if(CTX::instance()->mesh.recombineAll || gf->meshAttributes.recombine)
           gf->quadrangles.push_back(new MQuadrangle(v1, v2, v3, v4));
         else if(gf->meshAttributes.transfiniteArrangement == 1 ||
-                (gf->meshAttributes.transfiniteArrangement == 0 &&
+                (gf->meshAttributes.transfiniteArrangement == 2 &&
                  ((i % 2 == 0 && j % 2 == 1) ||
-                  (i % 2 == 1 && j % 2 == 0)))){
+                  (i % 2 == 1 && j % 2 == 0))) ||
+		(gf->meshAttributes.transfiniteArrangement == -2 &&
+                 ((i % 2 == 0 && j % 2 == 0) ||
+                  (i % 2 == 1 && j % 2 == 1)))
+		){
           gf->triangles.push_back(new MTriangle(v1, v2, v3));
           gf->triangles.push_back(new MTriangle(v3, v4, v1));
         }

Parser/Gmsh.y

@@ -3456,8 +3456,12 @@ TransfiniteArrangement :
         $$ = 1;
       else if(!strcmp($1, "Left"))
 	$$ = -1;
-      else // alternated
-        $$ = 0;
+      else if(!strcmp($1, "AlternateRight"))
+	$$ = 2;
+      else if(!strcmp($1, "AlternateLeft"))
+	$$ = -2;
+      else // "Alternate" -> "Alternate Right"
+	$$ = 2;
       Free($1);
     }
 ;

doc/CREDITS.txt

@@ -127,4 +127,5 @@ Kelleners, Romuald Conty, Renaud Sizaire, Michel Benhamou, Tom De Vuyst, Kris
 Van den Abeele, Simon Vun, Simon Corbin, Thomas De-Soza, Marcus Drosson, Antoine
 Dechaume, Jose Paulo Moitinho de Almeida, Thomas Pinchard, Corrado Chisari, Axel
 Hackbarth, Peter Wainwright, Jiri Hnidek, Thierry Thomas, Konstantinos Poulios,
-Laurent Van Miegroet, Shahrokh Ghavamian, Geordie McBain.
+Laurent Van Miegroet, Shahrokh Ghavamian, Geordie McBain, Jose Paulo Moitinho de
+Almeida, Guillaume Demesy.

doc/texinfo/gmsh.texi

@@ -2654,14 +2654,15 @@ as the preceding one). The optional argument `@code{Using Bump
 @var{expression}}' instructs the transfinite algorithm to distribute the
 nodes with a refinement at both ends of the line.
 
-@item Transfinite Surface @{ @var{expression-list} @} | "*" < = @{ @var{expression-list} @} > < Left | Right | Alternate > ;
+@item Transfinite Surface @{ @var{expression-list} @} | "*" < = @{ @var{expression-list} @} > < Left | Right | Alternate | AlternateRight | AlternateLeft > ;
 Selects surfaces to be meshed with the 2D transfinite algorithm. The
 @var{expression-list} on the right-hand-side should contain the
 identification numbers of three or four points on the boundary of the
 surface that define the corners of the transfinite interpolation. If no
 identification numbers are given, the transfinite algorithm will try to
 find the corners automatically. The optional argument specifies the way
-the triangles are oriented when the mesh is not recombined.
+the triangles are oriented when the mesh is not
+recombined. (@code{Alternate} is a synonym for @code{AlternateRight}).
 
 @item Transfinite Volume @{ @var{expression-list} @} | "*" < = @{ @var{expression-list} @} > ;
 Selects five- or six-face volumes to be meshed with the 3D transfinite