[Gmsh] rotation of cube formed from extruded plane surface fails when meshed.

[Christophe Geuzaine]

Hi Mark,

Extruded meshes (using Layers) are only supported on the unmodified geometrical extrusion, both with the built-in and the Opens Cascade kernels. The reason is that the mesh is generated using the original extrusion specification (translation vector or rotation): if the geometry is modified this specification becomes invalid. In some simple cases it could be recomputed (e.g. in your example), but in general cases (the shape gets cut by another one) it cannot...

We will add an explicit point about this in the docs.

Thanks for the feedback,

Christophe

> On 24 Oct 2017, at 22:01, kilgore trout <convectedacoustics at gmail.com> wrote:
> 
> Hi everyone.
> 
> If I specify four points, create lines to make a square, define a plane surface then extrude that surface to form a cube, then rotate that cube.....  meshing fails.  Can someone please tell me how to rotate my cube and mesh it okay please? :)
> 
> Best regards,
> 
> Mark.
> 
> Point(1) = {2.6, -0.2, 0, 1.0};
> Point(2) = {2.6, 0.3, 0, 1.0};
> Point(3) = {3.1, 0.3, 0, 1.0};
> Point(4) = {3.1, -0.2, 0, 1.0};
> Line(1) = {2, 3};
> Line(2) = {3, 4};
> Line(3) = {4, 1};
> Line(4) = {1, 2};
> Line Loop(1) = {1, 2, 3, 4};
> Plane Surface(1) = {1};
> 
> Extrude {0, 0, 1} {
>   Surface{1}; Layers{5}; Recombine;
> }
> 
> // Okay to here.  Mesh is valid.  Cube mesh generated.
> 
> Rotate {{0, 1, 0}, {0, 0, 0}, Pi/4} {
>   Point{6}; Point{10}; Point{5}; Point{14}; Point{3}; Point{4}; Point{2}; Point{1}; Line{7}; Line{6}; Line{9}; Line{8}; Line{12}; Line{2}; Line{16}; Line{1}; Line{11}; Line{20}; Line{3}; Line{4};
> }
> 
> // Add this line and the mesh fails.  How can I rotate my cube?
> _______________________________________________
> gmsh mailing list
> gmsh at onelab.info
> http://onelab.info/mailman/listinfo/gmsh


-- 
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science 
http://www.montefiore.ulg.ac.be/~geuzaine

Free software: http://gmsh.info | http://getdp.info | http://onelab.info