public PipeModelInfo(Knot knot, NodeMap nodeMap, Edge edge, Vector3 offset)
: base("pipe1")
{
Knot = knot;
NodeMap = nodeMap;
Edge = edge;
Node node1 = nodeMap.FromNode (edge);
Node node2 = nodeMap.ToNode (edge);
PositionFrom = node1.ToVector () + offset;
PositionTo = node2.ToVector () + offset;
Position = node1.CenterBetween (node2) + offset;
Direction = PositionTo - PositionFrom;
Direction.Normalize ();
Scale = Vector3.One * 10f;
// a pipe is movable
IsMovable = true;
}