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[KL <>]

Well,

I am not even sure about the wording anymore, too complicated.

I don't even understand which API I should use.

 

The context is 3D triangulation from an array of 3D points.

 

A high level triangulation function -> inject your points and get the minimum number of triangles from those, would be very handy.

This is the only thing I want.

 

Iterating over vertices is not good either because you don't have the logic of the triangles.

 

From there, I may create a 3D object.

Hence the associated constraint to have an optimized number of resulting triangles.

 

So, Sebastian, where should I look to achieve that ?

 

I am a lost sailor,

-- 

MKL

 

 

 

05.07.2022, 17:21, "Sebastien Loriot ( via cgal-discuss Mailing List)" <>:

I'm not sure to understand what is your problem. A minimal self
contained example that we can run and that shows your problem would
be perfect.

What I can tell from the code I see:
You are computing a 3 triangulations that consists of tetrahedra.
`finite_facets()` provides the range of face that are not connected
to the infinite vertex. A facet is given a std::pair of a Cell_handle
(tetrahedron) and the id of the vertex in the cell opposite to the
facet. About the access to the vertices of a facet, the %4 is here so
that the index stays in [0,3] while ignoring pair.second (that might or
might not be infinite).

HTH,

Sebastien.

On 7/5/22 14:46, KL ( via cgal-discuss Mailing List)
wrote:

 Hi,
 The issue: while the code below works, it returns too many triangles for
 a simple shape.
 So, for a square, instead of two triangles made by one of the diagonal
 of the square, I get four tris, because the two diagonals are connecting.
 I get my vertices using:
 using K = CGAL::Exact_predicates_inexact_constructions_kernel;
 using Triangulation = CGAL::Triangulation_3 <K>;
 using Cell_handle = Triangulation::Cell_handle;
 using Vertex_handle = Triangulation::Vertex_handle;
 using Locate_type = Triangulation::Locate_type;
 using Point_CGAL = Triangulation::Point;
 ...
 Triangulation tri;
 ...
 // load data
 ...
 //loop
 for ( auto &e : tri.finite_facets() ){
          auto &vert = *( e.first );
          auto starter_id = e.second;
          for ( u32 x = 1; x < 4; x += 1 ){
                  auto &pt = *( vert.vertex( ( starter_id + x ) % 4 )
 );                 // saw that line on the stackoverflow -> 3 finite
 vertices and 1 infinite vertice, hence the 4.
                  // store my result
          }
 }
 I need the triangulation to be the minimum number of tris for any given
 shape. A square should have 2 tris.
 I read the doc, but it is not among the easiest to wrap one's head around.
 What should I modify, please?
 Thanks
 --
 MKL
 
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