The concept SurfaceMeshShortestPathVisitor
describes the requirements of the visitor type used to collect the edges and vertices traversed by a shortest path on the surface of a triangulated surface mesh.
The methods are called in the order of the shortest path sequence along the surface, starting with the target point and ending with the source point.
void SurfaceMeshShortestPathVisitor::operator() 
( 
halfedge_descriptor 
edge, 


FT 
alpha 

) 
 
Called when an edge was traversed in the shortest path sequence.
 Parameters

edge  halfedge of the surface mesh crossed by the shortest path. The halfedge is directed toward the face nearest to the target point. 
alpha  value in the range [0.0,1.0] specifying where along edge the shortest path crossed.
 0.0 means it crossed at
source(edge)
 1.0 means it crossed at
target(edge)
 Any other value is linearly interpolated between the endpoints.

Note that values of 0.0 and 1.0 are possible in some situations, and may not be reported as vertices. In particular, this will occur if the vertex crossed by the path is not a saddle vertex (less than \(2\pi\) surface area). This is because from the perspective of the algorithm, this is indistinguishable from crossing anywhere else along the edge.