public static Vertex Create(Vertex v1, Vertex v2, double alpha)
{
var v = v2.ToPoint() - v1.ToPoint();
v = v / v.Length * alpha;
var p = v1.ToPoint() + v;
var vertex = new Vertex() { X = p.X, Y = p.Y, IsIntersect = true,Alpha = alpha};
return vertex;
}
public static bool Intersects(Vertex p1, Vertex p2, Vertex q1, Vertex q2, ref double alphaP, ref double alphaQ)
{
double wecP1 = (p1.X - q1.X) * (q2.Y - q1.Y) - (p1.Y - q1.Y) * (q2.X - q1.X);
double wecP2 = (p2.X - q1.X) * (q2.Y - q1.Y) - (p2.Y - q1.Y) * (q2.X - q1.X);
if (wecP1 * wecP2 <= 0)
{
double wecQ1 = (q1.X - p1.X) * (p2.Y - p1.Y) - (q1.Y - p1.Y) * (p2.X - p1.X);
double wecQ2 = (q2.X - p1.X) * (p2.Y - p1.Y) - (q2.Y - p1.Y) * (p2.X - p1.X);
if (wecQ1 * wecQ2 <= 0)
{
alphaP = wecP1 / (wecP1 - wecP2);
alphaQ = wecQ1 / (wecQ1 - wecQ2);
return true;
}
}
return false;
}
//public static void
public static List<List<Vertex>> Clip(Vertex subject, Vertex clip, ClipType clipType)
{
bool isIntersect = false;
//phase 1
for (var si = subject; si != null; si = si.Next == subject ? null : si.Next)
{
if (si.IsIntersect)
continue;
for (var cj = clip; cj != null; cj = cj.Next == clip ? null : cj.Next)
{
if (cj.IsIntersect)
continue;
var cross = Segment.Intersect (si.ToPoint(), si.NonIntersectionNext.ToPoint(),
cj.ToPoint(), cj.NonIntersectionNext.ToPoint());
if (cross.HasValue)
{
double a = cross.Value.DistanceBetween (si.ToPoint ()) /
si.ToPoint ().DistanceBetween (si.NonIntersectionNext.ToPoint ());
double b = cross.Value.DistanceBetween (cj.ToPoint ()) /
cj.ToPoint ().DistanceBetween (cj.NonIntersectionNext.ToPoint ());
Vertex i1 = new Vertex () {
X = cross.Value.X,
Y = cross.Value.Y,
IsIntersect = true,
Alpha = a,
};
Vertex i2 = new Vertex () {
X = cross.Value.X,
Y = cross.Value.Y,
IsIntersect = true,
Alpha = b,
};
i1.Neibour = i2;
i2.Neibour = i1;
i1.InsertTo (si, si.NonIntersectionNext);
i2.InsertTo (cj, cj.NonIntersectionNext);
isIntersect = true;
}
}
}
if(!isIntersect)
{
List<List<Vertex>> result = new List<List<Vertex>>();
if (subject.Contains(clip))
{
result.Add(clip.ToVertexList());
}
else if (clip.Contains(subject))
{
result.Add(subject.ToVertexList());
}
return result;
}
//phase 2
bool status = clip.Contains(subject);
if (clipType == ClipType.Union || clipType == ClipType.Difference)
status = !status;
for (var si = subject; si != null; si = si.Next == subject ? null : si.Next)
{
if (si.IsIntersect)
{
si.IsExit = status;
status = !status;
}
}
status = subject.Contains(clip);
if (clipType == ClipType.Union)
status = !status;
for (var cj = clip; cj != null; cj = cj.Next == clip ? null : cj.Next)
{
if (cj.IsIntersect)
{
cj.IsExit = status;
status = !status;
}
}
//phase 3
Vertex current;
List<List<Vertex>> polygonList = new List<List<Vertex>>();
for (var si = subject; si != null; si = si.Next == subject ? null : si.Next)
{
if (si.IsIntersect && !si.IsVisit)
{
current = si;
var polygon = new List<Vertex>();
polygonList.Add(polygon);
polygon.Add(current);
do
{
current.IsVisit = true;
if (current.IsExit)
{
do
{
current = current.Previous;
if(current.Neibour!= polygon[0])
polygon.Add(current);
current.IsVisit = true;
} while (!current.IsIntersect);
}
else
{
do
{
current = current.Next;
if(current.Neibour != polygon[0])
polygon.Add(current);
current.IsVisit = true;
} while (!current.IsIntersect);
}
current = current.Neibour;
} while (!current.IsVisit);
}
}
return polygonList;
}
public static List<List<Vertex>> Union(Vertex subject, Vertex clip)
{
return Clip(subject, clip, ClipType.Union);
}
public static List<List<Vertex>> Split(Vertex subject,Vertex polyline)
{
return null;
}
public static List<List<Vertex>> Intersect(Vertex subject,Vertex clip)
{
return Clip(subject, clip, ClipType.Inersection);
}
public static List<List<Vertex>> Diff(Vertex subject, Vertex clip)
{
return Clip(subject, clip, ClipType.Difference);
}
public bool Contains(Vertex point)
{
int windNumber = 0;
Vertex si = this;
do
{
if (si.Y <= point.Y)
{
if (si.Next.Y > point.Y)
{
if (Triangle.GetSignedArea(si.ToPoint(), si.Next.ToPoint(), point.ToPoint()) > 0)
windNumber++;
}
}
else
{
if (si.Next.Y <= point.Y)
if (Triangle.GetSignedArea(si.ToPoint(), si.Next.ToPoint(), point.ToPoint()) < 0)
windNumber--;
}
si = si.Next;
} while (si != this);
return (windNumber & 1) != 0;
}
public void InsertTo(Vertex start,Vertex end)
{
Vertex prev, next = start;
while (next != end && next.Alpha < Alpha)
next = next.Next;
prev = next.Previous;
Next = next;
Previous = prev;
prev.Next = this;
next.Previous = this;
}