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["Pedro Machado Manhães de Castro" <>]

Hello,

Do you define the neighborhood of your face inside your 2nd for iteration?

Stuffs like:
fHandle->set_neighbor(0, some_face_handle_1);
fHandle->set_neighbor(0, some_face_handle_2);
fHandle->set_neighbor(0, some_face_handle_3);
inside

?

This constructor here is easier to use:
create_face(Face_handle f1, int i1, 
                   Face_handle f2, int i2, 
                   Face_handle f3, int i3)

You define a face by its 3 neighbors, i1, i2, i3 are any sequence defined by the indices 0, 1, 2.

Hope it could help,
Best Regard,
Pedro Machado

On Tue, Mar 25, 2008 at 11:43 AM, Louis Feng <> wrote:

Hello,

I'm trying to construct a 2D triangle mesh from a list of vertices and
faces. I didn't want to use Polyhedron because I needed some properties from
the 2D triangulation class. I'm using Triangulation_2 and
Triangulation_data_structure_2. Basically I use T.tds() to get a reference
to the internal data structure. Then I add vertices and faces to it. But
this has become very confusing and I couldn't find examples on this.

An outline of my code:

triDS.set_dimension(2);
for(...) {
 VertexHandle vHandle = triDS.create_vertex();
 vHandle->set_point(Point2(...));
}
for(...) {
 FaceHandle fHandle = triDS.create_face(vHandle1, vHandle2, vHandle3); }

When I check triDS.is_valid() at the end, it returns false. More
interestingly, before I add anything to triDS, when I check the vertices,
edge, etc. I get this

Triangulation vertices: 0
Triangulation faces: 1
Triangulation full faces: 1
Triangulation edges: 1

So am I suppose to clear this before I add something to it? Looking at the
template file for the data structure, it check this:

case 2:
   result = result &&  edge_count == 3*face_count/2 ;
   CGAL_triangulation_assertion(edge_count == 3*face_count/2);
   break;

I'm not sure what the expected behavior is. Could someone tell me what I'm
doing wrong and how this class suppose to be used? Thanks!

Louis

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