Function S2Builder.forceVertex

Forces a vertex to be located at the given position. This can be used to prevent certain input vertices from moving. However if you are trying to preserve part of the input boundary, be aware that this option does not prevent edges from being split by new vertices.

void forceVertex (
  in const(s2.util.math.vector.Vector!(double,3L)) vertex
);

Forced vertices are never snapped; if this is desired then you need to call options().snap_function().SnapPoint() explicitly. Forced vertices are also never simplified away (if simplify_edge_chains() is used).

Caveat

Since this method can place vertices arbitrarily close together, S2Builder makes no minimum separation guaranteees with forced vertices.