/// <summary>
/// Checks if a segments end is another segments start.
/// </summary>
public bool Connected(Segment other)
{
if (/*this.Start.Equals(other.Start) || */this.Start.Equals(other.End) ||
this.End.Equals(other.Start)/* || this.End.Equals(other.End)*/)
{
return true;
}
return false;
}
/// <summary>
/// Adds a segment to the front.
/// </summary>
public void AddSegment(Segment segment)
{
double len = segment.GetLength();
if (!this.Segments.ContainsKey(len))
{
this.Segments.Add(len, new List<Segment>());
}
this.Segments[len].Add(segment);
segment.ConnectEndpoints();
}
/// <summary>
/// Checks if the front contains a segment.
/// </summary>
public bool Contains(Segment s, int cellDistance)
{
HashSet<Segment> segments = s.GetNearbySegments(this, cellDistance);//GetSegmentsUnordered();
foreach (Segment segment in segments)
{
if (segment.Equals(s))
{
return true;
}
}
return false;
}
public bool Equals(Segment other)
{
// start == start && end == end
if (this.Start.Equals(other.Start))
{
if (this.End.Equals(other.End))
return true;
}
// start == end && end == start (reverse dir)
if (this.Start.Equals(other.End))
{
if (this.End.Equals(other.Start))
return true;
}
return false;
}
public Front(List<Point> pts)
{
this.InitialPoints = pts;
this.Points = new Quadtree(this.InitialPoints);
this.Segments = new SortedList<double, List<Segment>>();
if (this.InitialPoints.Count == 0) return;
// Create segments between points.
for (int i = 0; i < this.InitialPoints.Count - 1; i++)
{
Segment seg = new Segment(this.InitialPoints[i], this.InitialPoints[i + 1]);
AddSegment(seg);
}
Segment s = new Segment(this.InitialPoints[this.InitialPoints.Count - 1],
this.InitialPoints[0]);
AddSegment(s);
}
/// <summary>
/// Calculates the angle of two connected segments in degrees.
/// </summary>
public static double Angle(Segment s1, Segment s2)
{
Vector3D v1, v2;
if (s1.End.Equals(s2.Start))
{
v1 = s1.ToVector3D();
v2 = s2.ToVector3D();
}
else if (s2.End.Equals(s1.Start))
{
v1 = s2.ToVector3D();
v2 = s1.ToVector3D();
}
else
{
throw new ApplicationException("Invalid segment order");
}
double temp = Math.Acos(Vector3D.DotProduct(v1, v2) / (v1.Length * v2.Length));
double angle = temp * (180 / Math.PI);
return Vector3D.CrossProduct(v1, v2).Z >= 0 ? 180 - angle : 180 + angle;
}
private bool TryFormTriangle(Segment shortestSegment, Point p, bool existingPoint)
{
Segment newSegment1 = new Segment(shortestSegment.Start, p);
Segment newSegment2 = new Segment(p, shortestSegment.End);
List<Segment> SegmentsToAdd = new List<Segment>();
List<Segment> SegmentsToRemove = new List<Segment>();
// Check if triangle can be formed
if (this.Front.Contains(newSegment1, cellDistance))
{
SegmentsToRemove.Add(newSegment1);
}
else
{
// Test if triangle candidate intersects with existing elements
if (IsIntersecting(newSegment1)) return false;
// Test if segment is outside of the front
if (!this.Front.IsPointInside(newSegment1.GetPoint(0.5))) return false;
SegmentsToAdd.Add(newSegment1);
}
if (this.Front.Contains(newSegment2, cellDistance))
{
SegmentsToRemove.Add(newSegment2);
}
else
{
// Test if triangle candidate intersects with existing elements
if (IsIntersecting(newSegment2)) return false;
// Test if segment is outside of the front
if (!this.Front.IsPointInside(newSegment2.GetPoint(0.5))) return false;
SegmentsToAdd.Add(newSegment2);
}
// update front and form triangle
// Remove current segment from the front.
this.Front.RemoveSegment(shortestSegment);
// Update front with new segments.
if (!existingPoint)
{
this.Points.Add(p);
this.Front.Points.Add(p);
}
foreach (Segment s in SegmentsToAdd)
{
this.Front.AddSegment(s);
}
foreach (Segment s in SegmentsToRemove)
{
this.Front.RemoveSegment(s);
}
AddTriangle(shortestSegment.Start, shortestSegment.End, p);
return true;
}
private void TryContractVertices(Segment s1, Segment s2)
{
Point p1, p2, common;
if (s1.End.Equals(s2.Start))
{
common = s1.End;
p1 = s1.Start;
p2 = s2.End;
}
else if (s1.Start.Equals(s2.End))
{
common = s1.Start;
p2 = s1.End;
p1 = s2.Start;
}
else
{
throw new ApplicationException("Invalid segment order");
}
if (p1.IsEdgePoint && p2.IsEdgePoint)
{
AddTriangle(p1, p2, common);
this.Front.AddSegment(new Segment(p1, p2));
}
else
{
Point midPoint;
if (p1.IsEdgePoint)
midPoint = p1;
else if (p2.IsEdgePoint)
midPoint = p2;
else
{
midPoint = new Point((p1.X + p2.X) / 2, (p1.Y + p2.Y) / 2, 0);
}
ReplacePoints(p1, p2, midPoint);
}
}
/// <summary>
/// Checks if the segment is intersecting with nearby front and mesh elements.
/// </summary>
private bool IsIntersecting(Segment s)
{
bool intersecting = false;
// Get nearby triangles
HashSet<Triangle> triangles = s.GetNearbyTriangles(this, cellDistance);
// Check intersection with nearby triangles
foreach (Triangle triangle in triangles)
{
Point p1 = s.Intersection(new Segment(triangle.Points[0], triangle.Points[1]));
Point p2 = s.Intersection(new Segment(triangle.Points[1], triangle.Points[2]));
Point p3 = s.Intersection(new Segment(triangle.Points[2], triangle.Points[0]));
if (p1 != null || p2 != null || p3 != null)
return true;
}
//Parallel.ForEach(triangles, (triangle, state) =>
//{
// Point p1 = s.Intersection(new Segment(triangle.Points[0], triangle.Points[1]));
// Point p2 = s.Intersection(new Segment(triangle.Points[1], triangle.Points[2]));
// Point p3 = s.Intersection(new Segment(triangle.Points[2], triangle.Points[0]));
// if (p1 != null || p2 != null || p3 != null)
// {
// intersecting = true;
// state.Stop();
// }
//});
// Get nearby segments of the front
HashSet<Segment> segments = s.GetNearbySegments(this.Front, cellDistance);
// Check intersecion with nearby segments
foreach (Segment other in segments)
{
Point p = s.Intersection(other);
if (p != null)
return true;
}
//Parallel.ForEach(segments, (other, state) =>
//{
// Point p = s.Intersection(other);
// if (p != null)
// {
// intersecting = true;
// state.Stop();
// }
//});
return false;
//return intersecting;
}
public Point Intersection(Segment other)
{
// Algo from stackoverflow
Vector3D p = this.Start.ToVector3D();
Vector3D q = other.Start.ToVector3D();
Vector3D s = other.End.ToVector3D() - q;
Vector3D r = this.End.ToVector3D() - p;
Vector3D qmp = q - p;
Vector3D rxs = new Vector3D(0, 0, s.X * r.Y - r.X * s.Y);//Vector3D.CrossProduct(r, s);
Vector3D qmpxr = new Vector3D(0, 0, r.X * qmp.Y - qmp.X * r.Y);//Vector3D.CrossProduct(qmp, r);
Vector3D qmpxs = new Vector3D(0, 0, s.X * qmp.Y - qmp.X * s.Y);//Vector3D.CrossProduct(qmp, s);
if (/*rxs.Z == 0 && qmpxr.Z == 0.0*/ Math.Abs(rxs.Z) < Geometry.Epsilon
&& Math.Abs(qmpxr.Z) < Geometry.Epsilon && qmp.Length > Geometry.Epsilon)
{
// Collinear
//p p+r q q+s
if (p.X > Math.Min(q.X, (q + s).X) && p.X < Math.Max(q.X, (q + s).X) &&
p.Y > Math.Min(q.Y, (q + s).Y) && p.Y < Math.Max(q.Y, (q + s).Y))
return new Point(p.X, p.Y, 0.0);
if ((p + r).X > Math.Min(q.X, (q + s).X) && (p + r).X < Math.Max(q.X, (q + s).X) &&
(p + r).Y > Math.Min(q.Y, (q + s).Y) && (p + r).Y < Math.Max(q.Y, (q + s).Y))
return new Point((p + r).X, (p + r).Y, 0.0);
if (q.X > Math.Min(p.X, (p + r).X) && q.X < Math.Max(p.X, (p + r).X) &&
q.Y > Math.Min(p.Y, (p + r).Y) && q.Y < Math.Max(p.Y, (p + r).Y))
return new Point(q.X, q.Y, 0.0);
if ((q + s).X > Math.Min(p.X, (p + r).X) && (q + s).X < Math.Max(p.X, (p + r).X) &&
(q + s).Y > Math.Min(p.Y, (p + r).Y) && (q + s).Y < Math.Max(p.Y, (p + r).Y))
return new Point((q + s).X, (q + s).Y, 0.0);
return null;
}
if (Math.Abs(rxs.Z) < Geometry.Epsilon)
{
// Parallel.
return null;
}
double t = qmpxs.Z / rxs.Z;
double u = qmpxr.Z / rxs.Z;
if ((t > 0.0 + Geometry.Epsilon) && (t < 1.0 - Geometry.Epsilon) &&
(u > 0.0 + Geometry.Epsilon) && (u < 1.0 - Geometry.Epsilon))
{
return this.GetPoint(t);
}
return null;
}
/// <summary>
/// Removes the points from the front that are not part of any
/// segment of the front.
/// </summary>
private void RemoveUnconnectedEndpoints(Segment s)
{
bool endRemains = false;
bool startRemains = false;
foreach (Segment segment in this.GetSegmentsUnordered())
{
if (s.End.Equals(segment.End) || s.End.Equals(segment.Start))
{
endRemains = true;
}
}
foreach (Segment segment in this.GetSegmentsUnordered())
{
if (s.Start.Equals(segment.End) || s.Start.Equals(segment.Start))
{
startRemains = true;
}
}
if (!endRemains) this.Points.Remove(s.End);
if (!startRemains) this.Points.Remove(s.Start);
}
public bool RemoveSegment(Segment s)
{
bool removed = false;
double? toRemove = null;
foreach (var item in this.Segments)
{
Segment sToRemove = null;
foreach (Segment segment in item.Value)
{
if (s.Equals(segment))
{
sToRemove = segment;
//if (item.Value.Count == 0)
//{
// Segments.Remove(item.Key);
//}
}
}
if (sToRemove != null)
{
item.Value.RemoveAll(seg => seg.Equals(sToRemove));
removed = true;
}
if (item.Value.Count == 0)
{
toRemove = item.Key;
}
}
if (toRemove != null)
{
this.Segments.Remove((double)toRemove);
}
RemoveUnconnectedEndpoints(s);
s.DisconnectEndpoints();
return removed;
}