Question:
How to erase a vertex of a Polygon annot. There is only GetVertex and SetVertex?
Answer:
The vertices are stored under an entry called Vertices, which is an array of numbers, where each vertex is a pair of numbers in order of x,y.
So to erase the nth vertex simply call the following.
Obj vertices = polygon.GetSDFObj().FindObj("Vertices");
if(vertices != null && vertices.IsArray())
{
vertices.EraseAt(n*2); // erase x value
vertices.EraseAt(n*2); // erase y value
}
This also applies for Polyline annotations.