How to convert 2D mesh geometry into 3D?

Question

I'm trying to rotate a 2D mesh (generated from Rectangle) around the x-axis, but rotate complains that it can only rotate around z. Is there an easy way to convert its dimension from 2 to 3? I've tried editing/replacing the mesh.coordinates() directly, but this causes a seg fault.

Comments

For those wondering, it looks easier to construct the plane with the desired normal using netgen, currently in the development version of FEnics.

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Answer 1

I was just trying to do this to plot a parametric 2D surface in 3D, and found the following useful:

Googling fenics embedded mesh gave some test source code to create meshes with the right topology using the BoundaryMesh constructor:
https://github.com/FEniCS/dolfin/blob/master/test/unit/fem/python/Form.py

So I can create a 3D throw-away mesh and extract a useful
surface.

Benjamin Kehlet (benjamik) wrote some nice example code for generating meshes from CSG entities using CGAL:
https://answers.launchpad.net/fenics/+question/214429
He referenced the manual at: http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Mesh_3/Chapter_main.html

c = Cone(Point(0, 0, -1), Point(0, 0, 1), .5, 1.0)
def setparams(): # optional
  generator = CSGCGALMeshGenerator3D(c)
  generator.parameters["cell_size"] = 0.1
m = Mesh(c, 16)

So the full source is here:

def CutMesh(mesh, theTest):
    class TheCut(SubDomain):
        def inside(self, x, on_boundary):
            return theTest(x)
    cut = TheCut()

    # Initialize mesh function for interior domains
    subdomains = CellFunction('size_t', mesh)
    subdomains.set_all(0)
    cut.mark(subdomains, 1)

    return SubMesh(mesh, subdomains, 1)

def embeddedDisk(rmax, res, h): # res = int(2/h) works well.
   C = 2*pi*rmax
   cyl = Cylinder(Point(0,0,1), Point(0,0,0), rmax, int(0.5*C/h))
   mesh = Mesh(cyl, res)
   omega = BoundaryMesh(mesh, "exterior")
   disk = CutMesh(omega, lambda x: abs(x[2]-0.0) < 1e-8)

   return disk

Comments

Thanks! I was having problems getting the developer version installed and had basically given up. I was going to try constructing a mesh in Open-dx and importing (if that's still supported). It is kindof strange how awkward this is.