Export triangulation to Paraview

Function to export an unrestricted 2D triangulation to a VTK file which can be open with Paraview.

Trying to visualize a huge triangulation with trisurf or triplot is often very slow and frustrating. Solution : use Paraview, a very powerful and free 3D data viewer. But it could be complicated to generate the input file specially with binary format. The function proposed takes a 2.5D unrestricted triangulation and generates the ASCII VTK file for Paraview.

function exportTriangulation2VTK(file,XYZ,tri,dir)
Input :
"dir" is the path of the directory where the file is saved (string). (Optional)
"file" is the name without extension of the file (string).
"XYZ" is the coordinate of the vertex of the triangulation (nx3 matrix).
"tri" is the list of triangles which contain indexes of XYZ (mx3 matrix).

Simple example :
[X,Y,Z]=peaks(25);
X=reshape(X,[],1);
Y=reshape(Y,[],1);
Z=0.4*reshape(Z,[],1);
tri = delaunay(X,Y);
exportTriangulation2VTK('sampleExampleTri',[X Y Z],tri)

Note : If the triangulation doesn't have Z component (a plane), put the third column of XYZ with all zeros. Paraview only deals with 3D object.