void write_graph(DGraph2 graph, StreamWriter w)
{
string style = get_style(graph, ref DefaultDGraphStyle);
StringBuilder b = new StringBuilder();
foreach (int eid in graph.EdgeIndices())
{
Segment2d seg = graph.GetEdgeSegment(eid);
b.Append("<line ");
append_property("x1", seg.P0.x, b, true);
append_property("y1", seg.P0.y, b, true);
append_property("x2", seg.P1.x, b, true);
append_property("y2", seg.P1.y, b, true);
b.Append(style);
b.Append(" />");
b.AppendLine();
}
w.WriteLine(b);
}
/// <summary>
/// insert edge [a,b] into the arrangement, splitting existing edges as necessary
/// </summary>
protected bool insert_segment(ref Vector2d a, ref Vector2d b, int gid = -1, double tol = 0)
{
// handle degenerate edges
int a_idx = find_existing_vertex(a);
int b_idx = find_existing_vertex(b);
if (a_idx == b_idx && a_idx >= 0)
{
return(false);
}
// ok find all intersections
List <Intersection> hits = new List <Intersection>();
find_intersecting_edges(ref a, ref b, hits, tol);
int N = hits.Count;
// we are going to construct a list of <t,vertex_id> values along segment AB
List <SegmentPoint> points = new List <SegmentPoint>();
Segment2d segAB = new Segment2d(a, b);
// insert intersections into existing segments
for (int i = 0; i < N; ++i)
{
Intersection intr = hits[i];
int eid = intr.eid;
double t0 = intr.intr.Parameter0, t1 = intr.intr.Parameter1;
// insert first point at t0
int new_eid = -1;
if (intr.intr.Type == IntersectionType.Point || intr.intr.Type == IntersectionType.Segment)
{
Index2i new_info = split_segment_at_t(eid, t0, VertexSnapTol);
new_eid = new_info.b;
Vector2d v = Graph.GetVertex(new_info.a);
points.Add(new SegmentPoint()
{
t = segAB.Project(v), vid = new_info.a
});
}
// if intersection was on-segment, then we have a second point at t1
if (intr.intr.Type == IntersectionType.Segment)
{
if (new_eid == -1)
{
// did not actually split edge for t0, so we can still use eid
Index2i new_info = split_segment_at_t(eid, t1, VertexSnapTol);
Vector2d v = Graph.GetVertex(new_info.a);
points.Add(new SegmentPoint()
{
t = segAB.Project(v), vid = new_info.a
});
}
else
{
// find t1 was in eid, rebuild in new_eid
Segment2d new_seg = Graph.GetEdgeSegment(new_eid);
Vector2d p1 = intr.intr.Segment1.PointAt(t1);
double new_t1 = new_seg.Project(p1);
Util.gDevAssert(new_t1 <= Math.Abs(new_seg.Extent));
Index2i new_info = split_segment_at_t(new_eid, new_t1, VertexSnapTol);
Vector2d v = Graph.GetVertex(new_info.a);
points.Add(new SegmentPoint()
{
t = segAB.Project(v), vid = new_info.a
});
}
}
}
// find or create start and end points
if (a_idx == -1)
{
a_idx = find_existing_vertex(a);
}
if (a_idx == -1)
{
a_idx = Graph.AppendVertex(a);
PointHash.InsertPointUnsafe(a_idx, a);
}
if (b_idx == -1)
{
b_idx = find_existing_vertex(b);
}
if (b_idx == -1)
{
b_idx = Graph.AppendVertex(b);
PointHash.InsertPointUnsafe(b_idx, b);
}
// add start/end to points list. These may be duplicates but we will sort that out after
points.Add(new SegmentPoint()
{
t = segAB.Project(a), vid = a_idx
});
points.Add(new SegmentPoint()
{
t = segAB.Project(b), vid = b_idx
});
// sort by t
points.Sort((pa, pb) => { return((pa.t < pb.t) ? -1 : ((pa.t > pb.t) ? 1 : 0)); });
// connect sequential points, as long as they aren't the same point,
// and the segment doesn't already exist
for (int k = 0; k < points.Count - 1; ++k)
{
int v0 = points[k].vid;
int v1 = points[k + 1].vid;
if (v0 == v1)
{
continue;
}
if (Math.Abs(points[k].t - points[k + 1].t) < MathUtil.Epsilonf)
{
System.Console.WriteLine("insert_segment: different points with same t??");
}
if (Graph.FindEdge(v0, v1) == DGraph2.InvalidID)
{
Graph.AppendEdge(v0, v1, gid);
}
}
return(true);
}