new "Background Mesh" command

Parser/Gmsh.y

 %{
-// $Id: Gmsh.y,v 1.217 2006-01-28 21:13:35 geuzaine Exp $
+// $Id: Gmsh.y,v 1.218 2006-01-28 21:44:22 geuzaine Exp $
 //
 // Copyright (C) 1997-2006 C. Geuzaine, J.-F. Remacle
 //
@@ -1799,6 +1799,17 @@ Command :
       }
       Free($1); Free($2); Free($6);
     }
+  | tSTRING tSTRING tSTRING '[' FExpr ']' tEND
+    {
+      if(!strcmp($1, "Background") && !strcmp($2, "Mesh")  && !strcmp($3, "View")){
+	Post_View **vv = (Post_View **)List_Pointer_Test(CTX.post.list, (int)$5);
+	if(vv) BGMWithView(*vv);
+      }
+      else{
+	yymsg(GERROR, "Unknown command '%s'", $1);
+      }
+      Free($1); Free($2); Free($3);
+    }
   | tSTRING FExpr tEND
     {
       if(!strcmp($1, "Sleep")){

Parser/Gmsh.yy.cpp

@@ -2,7 +2,7 @@
 /* A lexical scanner generated by flex */
 
 /* Scanner skeleton version:
- * $Header: /cvsroot/gmsh/Parser/Gmsh.yy.cpp,v 1.250 2006-01-28 21:16:36 geuzaine Exp $
+ * $Header: /cvsroot/gmsh/Parser/Gmsh.yy.cpp,v 1.251 2006-01-28 21:44:22 geuzaine Exp $
  */
 
 #define FLEX_SCANNER
@@ -725,7 +725,7 @@ char *yytext;
 #line 1 "Gmsh.l"
 #define INITIAL 0
 #line 2 "Gmsh.l"
-// $Id: Gmsh.yy.cpp,v 1.250 2006-01-28 21:16:36 geuzaine Exp $
+// $Id: Gmsh.yy.cpp,v 1.251 2006-01-28 21:44:22 geuzaine Exp $
 //
 // Copyright (C) 1997-2006 C. Geuzaine, J.-F. Remacle
 //

doc/texinfo/gmsh.texi

 \input texinfo.tex @c -*-texinfo-*-
-@c $Id: gmsh.texi,v 1.197 2006-01-28 21:16:36 geuzaine Exp $
+@c $Id: gmsh.texi,v 1.198 2006-01-28 21:44:23 geuzaine Exp $
 @c
 @c Copyright (C) 1997-2006 C. Geuzaine, J.-F. Remacle
 @c
@@ -1942,15 +1942,16 @@ Attractors only work with the 2D anisotropic algorithm (see the
 You can give Gmsh an explicit background mesh in the form of a scalar
 post-processing view (see @ref{Post-processing commands}, and @ref{File
 formats}) in which the nodal values are the target element sizes.  This
-method is very general but it requires a first (usually rough) mesh and a
-way to compute the target sizes on this mesh (usually through an error
-estimation procedure, in an iterative process of mesh adaptation). Note that
-the target element sizes can be constrained by the characteristic lengths
-defined in the geometrical model if the
-@code{Mesh.ConstrainedBackgroundMesh} option is set. To load a background
-mesh, use the @code{-bgm} command-line option (@pxref{Command-line options})
-or select `Apply as background mesh' in the post-processing view option
-menu.
+method is very general but it requires a first (usually rough) mesh and
+a way to compute the target sizes on this mesh (usually through an error
+estimation procedure, in an iterative process of mesh adaptation). Note
+that the target element sizes can be constrained by the characteristic
+lengths defined in the geometrical model if the
+@code{Mesh.ConstrainedBackgroundMesh} option is set. To load a
+background mesh, you can use the @code{-bgm} command-line option
+(@pxref{Command-line options}), select `Apply as background mesh' in the
+post-processing view option menu, or use the @code{Background Mesh}
+command in a script (@pxref{Post-processing commands}).
 
 Background meshes are supported by all algorithms except the algorithms
 based on Netgen.
@@ -2353,6 +2354,10 @@ post-processing view numbers start at 0.
 @item Delete Empty Views;
 Deletes (removes) all the empty post-processing views.
 
+@item Background Mesh View[@var{expression}];
+Applies the @var{expression}-th post-processing view as the current
+background mesh. Note that post-processing view numbers start at 0.
+
 @item Plugin (@var{string}) . Run;
 Executes the plugin @var{string}. The list of default plugins is given in
 @ref{Post-processing plugins}.