Generate dijkstra distances for the vertices and match triangles, that share a common
edge of the dijkstra level lines; somewhere triangles might have more possible matching
partners, these will matched to one of them.
Draws an arc bounded by the specified rectangle from startAngle to
endAngle. 0 degrees is at the 3-o'clock position.Positive arc
angles indicate counter-clockwise rotations, negative arc angles are
drawn clockwise.
Get the dual PgElementSet: Each vertex will be replaced by an element, having the
center points of the adjacent elements as vertices; new boundary elements get two additional
vertices at the boundary edge midpoints, if the vertex had only one adjacent element, the new element
will contain also the old vertex.