protected void UpdateVertexReflexity(PartitionVertex v)
{
PartitionVertex v1 = null, v3 = null;
v1 = v.previous;
v3 = v.next;
v.isConvex = !IsReflex(v1.p, v.p, v3.p);
}
protected void UpdateVertexReflexity(PartitionVertex v)
{
PartitionVertex v1 = null, v3 = null;
v1 = v.Previous;
v3 = v.Next;
v.IsConvex = !IsReflex(v1.P, v.P, v3.P);
}
protected bool InCone(PartitionVertex v, TpplPoint p)
{
TpplPoint p1, p2, p3;
p1 = v.Previous.P;
p2 = v.P;
p3 = v.Next.P;
return(InCone(p1, p2, p3, p));
}
protected bool InCone(PartitionVertex v, TPPLPoint p)
{
TPPLPoint p1, p2, p3;
p1 = v.previous.p;
p2 = v.p;
p3 = v.next.p;
return(InCone(p1, p2, p3, p));
}
protected void UpdateVertex(PartitionVertex v, List <PartitionVertex> vertices)
{
int i;
PartitionVertex v1 = null, v3 = null;
TpplPoint vec1, vec3;
v1 = v.Previous;
v3 = v.Next;
v.IsConvex = IsConvex(v1.P, v.P, v3.P);
vec1 = Normalize(v1.P - v.P);
vec3 = Normalize(v3.P - v.P);
v.Angle = vec1.X * vec3.X + vec1.Y * vec3.Y;
if (v.IsConvex)
{
v.IsEar = true;
int numvertices = vertices.Count;
for (i = 0; i < numvertices; i++)
{
if ((vertices[i].P.X == v.P.X) && (vertices[i].P.Y == v.P.Y))
{
continue;
}
if ((vertices[i].P.X == v1.P.X) && (vertices[i].P.Y == v1.P.Y))
{
continue;
}
if ((vertices[i].P.X == v3.P.X) && (vertices[i].P.Y == v3.P.Y))
{
continue;
}
if (IsInside(v1.P, v.P, v3.P, vertices[i].P))
{
v.IsEar = false;
break;
}
}
}
else
{
v.IsEar = false;
}
}
protected void UpdateVertex(PartitionVertex v, List <PartitionVertex> vertices)
{
int i;
PartitionVertex v1 = null, v3 = null;
TPPLPoint vec1, vec3;
v1 = v.previous;
v3 = v.next;
v.isConvex = IsConvex(v1.p, v.p, v3.p);
vec1 = Normalize(v1.p - v.p);
vec3 = Normalize(v3.p - v.p);
v.angle = vec1.X * vec3.X + vec1.Y * vec3.Y;
if (v.isConvex)
{
v.isEar = true;
int numvertices = vertices.Count();
for (i = 0; i < numvertices; i++)
{
if ((vertices[i].p.X == v.p.X) && (vertices[i].p.Y == v.p.Y))
{
continue;
}
if ((vertices[i].p.X == v1.p.X) && (vertices[i].p.Y == v1.p.Y))
{
continue;
}
if ((vertices[i].p.X == v3.p.X) && (vertices[i].p.Y == v3.p.Y))
{
continue;
}
if (IsInside(v1.p, v.p, v3.p, vertices[i].p))
{
v.isEar = false;
break;
}
}
}
else
{
v.isEar = false;
}
}
private static void UpdateVertex(PartitionVertex v, PartitionVertex[] vertices, int numvertices)
{
PartitionVertex v1 = v.previous;
PartitionVertex v3 = v.next;
v.isConvex = IsConvex(v1.p, v.p, v3.p);
Vector2 vec1 = Normalize(v1.p - v.p);
Vector2 vec3 = Normalize(v3.p - v.p);
v.angle = vec1.x * vec3.x + vec1.y * vec3.y;
if (v.isConvex)
{
v.isEar = true;
for (int i = 0; i < numvertices; i++)
{
if ((vertices[i].p.x == v.p.x) && (vertices[i].p.y == v.p.y))
{
continue;
}
if ((vertices[i].p.x == v1.p.x) && (vertices[i].p.y == v1.p.y))
{
continue;
}
if ((vertices[i].p.x == v3.p.x) && (vertices[i].p.y == v3.p.y))
{
continue;
}
if (IsInside(v1.p, v.p, v3.p, vertices[i].p))
{
v.isEar = false;
break;
}
}
}
else
{
v.isEar = false;
}
}
public int Triangulate_EC(TpplPoly poly, List <TpplPoly> triangles)
{
int numvertices;
List <PartitionVertex> vertices = null;
PartitionVertex ear = null;
TpplPoly triangle = new TpplPoly();
int i, j;
bool earfound;
if (poly.Count < 3)
{
return(0);
}
if (poly.Count == 3)
{
triangles.Add(poly);
return(1);
}
numvertices = poly.Count;
vertices = new List <PartitionVertex>(numvertices);
for (i = 0; i < numvertices; i++)
{
vertices.Add(new PartitionVertex());
}
for (i = 0; i < numvertices; i++)
{
vertices[i].IsActive = true;
vertices[i].P = poly[i];
if (i == (numvertices - 1))
{
vertices[i].Next = vertices[0];
}
else
{
vertices[i].Next = vertices[i + 1];
}
if (i == 0)
{
vertices[i].Previous = vertices[numvertices - 1];
}
else
{
vertices[i].Previous = vertices[i - 1];
}
}
for (i = 0; i < numvertices; i++)
{
UpdateVertex(vertices[i], vertices);
}
for (i = 0; i < numvertices - 3; i++)
{
earfound = false;
//find the most extruded ear
for (j = 0; j < numvertices; j++)
{
if (!vertices[j].IsActive)
{
continue;
}
if (!vertices[j].IsEar)
{
continue;
}
if (!earfound)
{
earfound = true;
ear = vertices[j];
}
else
{
if (vertices[j].Angle > ear.Angle)
{
ear = vertices[j];
}
}
}
if (!earfound)
{
vertices.Clear();
return(0);
}
triangle = new TpplPoly(ear.Previous.P, ear.P, ear.Next.P);
triangles.Add(triangle);
ear.IsActive = false;
ear.Previous.Next = ear.Next;
ear.Next.Previous = ear.Previous;
if (i == numvertices - 4)
{
break;
}
UpdateVertex(ear.Previous, vertices);
UpdateVertex(ear.Next, vertices);
}
for (i = 0; i < numvertices; i++)
{
if (vertices[i].IsActive)
{
triangle = new TpplPoly(vertices[i].Previous.P, vertices[i].P, vertices[i].Next.P);
triangles.Add(triangle);
break;
}
}
vertices.Clear();
return(1);
}
// Triangulates a polygon by ear clipping
// time complexity O(n^2), n is the number of vertices
// space complexity: O(n)
// params:
// poly : an input polygon to be triangulated
// vertices have to be in counter-clockwise order
// triangles : a list of triangles (result)
// returns true on success, false on failure
private static bool Triangulate_EC(TPPLPoly poly, out TPPLPolyList triangles)
{
triangles = new TPPLPolyList();
if (!poly.Valid())
{
return(false);
}
int numvertices = poly.NumPoints;
if (numvertices < 3)
{
return(false);
}
if (numvertices == 3)
{
triangles.Add(poly);
return(true);
}
PartitionVertex[] vertices = new PartitionVertex[numvertices];
PartitionVertex ear = null;
for (int i = 0; i < numvertices; i++)
{
vertices[i] = new PartitionVertex();
}
for (int i = 0; i < numvertices; i++)
{
vertices[i].isActive = true;
vertices[i].p = poly.GetPoint(i);
if (i == (numvertices - 1))
{
vertices[i].next = vertices[0];
}
else
{
vertices[i].next = vertices[i + 1];
}
if (i == 0)
{
vertices[i].previous = vertices[numvertices - 1];
}
else
{
vertices[i].previous = vertices[i - 1];
}
}
for (int i = 0; i < numvertices; i++)
{
UpdateVertex(vertices[i], vertices, numvertices);
}
for (int i = 0; i < numvertices - 3; i++)
{
bool earfound = false;
//find the most extruded ear
for (int j = 0; j < numvertices; j++)
{
if (!vertices[j].isActive)
{
continue;
}
if (!vertices[j].isEar)
{
continue;
}
if (!earfound)
{
earfound = true;
ear = vertices[j];
}
else
{
if (vertices[j].angle > ear.angle)
{
ear = vertices[j];
}
}
}
if (!earfound)
{
return(false);
}
triangles.Add(new TPPLPoly(ear.previous.p, ear.p, ear.next.p));
ear.isActive = false;
ear.previous.next = ear.next;
ear.next.previous = ear.previous;
if (i == numvertices - 4)
{
break;
}
UpdateVertex(ear.previous, vertices, numvertices);
UpdateVertex(ear.next, vertices, numvertices);
}
for (int i = 0; i < numvertices; i++)
{
if (vertices[i].isActive)
{
triangles.Add(new TPPLPoly(vertices[i].previous.p, vertices[i].p, vertices[i].next.p));
break;
}
}
return(true);
}
