what does tm_src and tm_tgt mean in PMPCorefinementVisitor::after_vertex_copy() function ?

[citystrawman]

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Issue Details

I am trying to use

PMPCorefinementVisitor::after_vertex_copy(vertex_descriptor v_src, const Mesh& tm_src,
        vertex_descriptor  v_tgt , Mesh& tm_tgt)

in split method:
PMP::split(tm, splitter, params::visitor(v), params::do_not_modify(true));,
however, I am not quite clear about the meaning of tm_src and tm_tgt in this function:

As you can see, here tm_src and tm_tgt are both exactly the same in terms of their vertex as well as halfedges, and they both seems to be the same as tm in split function.

Then my question is, since they are all same, why they are differentiated as tm_src and tm_tgt ?

Environment

• Operating system (Windows/Mac/Linux, 32/64 bits):
• Compiler:
• Release or debug mode:
• Specific flags used (if any):
• CGAL version:
• Boost version:
• Other libraries versions if used (Eigen, TBB, etc.):

[sloriot]

For split, they are indeed the same. The visitor concept is used by several functions, it is not specific to split.

[citystrawman]

For split, they are indeed the same. The visitor concept is used by several functions, it is not specific to split.

Thanks. Then may I know what is the difference between v_src and v_tgt ? I tried to use add_property_map and plot v_src and v_tgt separately, for v_src it is obvious: they are the intersected points of tm and splitter, but for v_tgt I could not find them out in the output mesh.