[Gmsh] Gmsh 2.0 quad recombine

Lutz Nietner lutz.nietner at bilfinger.de
Tue Jul 3 07:57:24 CEST 2007


Dear all,

I've been using Gmsh 1.65 for generating 2D-quads in my own code, basing on
snippets like that:

Mesh.Algorithm = 2;
Mesh.RecombineAlgo = 2;
Point(1) = {0,0,0,0.1};
Point(2) = {0,2,0,0.1};
Point(3) = {0,1.93185165257814,-0.517638090205042,0.1};
Point(4) = {0,1.73205080756888,-1,0.1};
Point(5) = {0,1.4142135623731,-1.41421356237309,0.1};
Point(6) = {0,1,-1.73205080756888,0.1};
Point(7) = {0,0.517638090205041,-1.93185165257814,0.1};
Point(8) = {0,1.22460635382238E-16,-2,0.1};
Line(1) = {1,2};
Line(2) = {2,3};
Line(3) = {3,4};
Line(4) = {4,5};
Line(5) = {5,6};
Line(6) = {6,7};
Line(7) = {7,8};
Line(8) = {8,1};
Line Loop(9) = {1,2,3,4,5,6,7,8};
Plane Surface(10) = {9};
Recombine Surface {10};

In release 1.65, the code above produces always a good unstructured quad
pattern. In release 2, the recombine algorithm sometimes leaves triangles.
What's the reason for?

Best regards

Lutz Nietner