CGAL mesh boolean original faces outlines

[petrasvestartas]

Mesh Boolean methods can track original face indices:
#5440

Is there a method or an example that could help to recontruct polylines of these triangle groups?

At ethz we use cgal for geometry like this, but the triangulation of that comes out of cgal can hardly be used for structural calculations and fabrications applications.

We really need to output clean polygons. We can do this in python but on c++ cgal it would be much faster.

Input geometry that is interesecting with side beams:

Blocks are boolean differenced by cgal method:

Then we detect overlapping triangle faces, but due to mesh triangulation it is not usuable:

We somehow a clean output comming from boolean difference.

[sloriot]

I don't understand what you want. Could you explain what is the input and what is the output, and what extra information you would need.

[petrasvestartas]

@sloriot

Input: two meshes
Method: boolean difference
Output: outer polyline of triangle groups, where each subgroup belongs to original face index.

I essentially need outlines of triangulation groups.

In the example below from our original discussion, a cube is booleaned with another geometry.
I can display colors because of the face index tracking.
But i need the outlines of each color.

This is another image from my thesis, the lines are single lines, but i need closed face polygons. Since mesh boolean methods can track original faces, maybe there is a possibility to detect closed cycles within individual original face groups?

Once you cut even a simple quad, you might have a lot of triangles, but i need their groups either joined welded together or their joined edges to represents outlines and holes. As if you would be doing Brep boolean.

[sloriot]

If I got it correctly, it is what you have if you put in the output named parameter a edge_is_constrained_map(). You have some example usage here.