CGAL users discussion list

[rytis <>]

Hello,

I am a beginner with CGAL which I like very much so far. I think there is an issue (of documentation) with constrained Delaunay triangulation. The issue is below, but first, I want to describe the problem. If someone could indicate how solve my indexation problem, that would be nice too!

Problem:
I need to create a 2d mesh from "thin air" + boundaries (as if by Delaunay_mesher_2) but I must insert a few points which remain constant (that don't disappear or change their coordinates -- as if they were "punctual" constraints).


Issue:
Is it correct that,
A) refine_Delaunay_mesh_2 takes vertices as constants, so that, in particular, vertex_handles remain valid throughout the refinement procedure, and that no new vertices are added, whereas
B) Delaunay_mesher_2 invalidates vertex_handles, by possibly adding and/or removing some of them in the process of refinement?

So far this is what I tried to solve my problem:

1: insert boundary nodes and set boundary constraints,
2: run B) to generate a "new" triangulation
3: insert my "custom" vertices,
4: run A) (expecting that vertices remain constant)

I have to generate two types of output for nodes and links, respectively
ID,x,y
...

ID,ID
...

For that, I keep vertex handles in a map like this:
map<string,Vertex_handle> node_map;

this map is updated  after each step like so: node_map[ID]=Vertex_handle(Vertex_iterator);

which allows the retrieval of the vertex coordinates by their ID.

I noticed that during step 4 some of the vertex handles were not matched by an ID which makes me think that A) is incorrect (Help!) I checked that those vertices inserted at step 3 were still present though (Help....)

Thanks,
Rytis