private bool IsEar(int i, int indexBefore, int indexAfter, List<int> reflex)
{
if (reflex.Contains(i)) return false;
Triangle t = new Triangle(GetPos(Vertices[i]), GetPos(Vertices[indexBefore]), GetPos(Vertices[indexAfter]));
for (int j = 0; j < reflex.Count; j++)
{
int index = reflex[j];
if (index == i || index == indexBefore || index == indexAfter)
continue;
if (t.PointInTriangle(GetPos(Vertices[index])))
{
return false;
}
}
return true;
}
private Triangle[] Triangulate()
{
List<Triangle> triangles = new List<Triangle>();
Queue<int> ears = new Queue<int>();
List<int> reflex;
List<int> convex;
List<int> removed;
reflex = new List<int>();
convex = new List<int>();
removed = new List<int>();
// Find convex and reflex verts (initial)
for (int i = 0; i < Vertices.Length; i++)
{
int indexBefore = (i == 0) ? (Vertices.Length - 1) : (i - 1);
int indexAfter = (i == Vertices.Length - 1) ? (0) : (i + 1);
if (IsConvexVert(i, indexBefore, indexAfter))
convex.Add(i);
else reflex.Add(i);
}
// Find ears (initial)
for (int i = 0; i < convex.Count; i++)
{
int indexBefore = (i == 0) ? (Vertices.Length - 1) : (i - 1);
int indexAfter = (i == Vertices.Length - 1) ? (0) : (i + 1);
if (IsEar(i, indexBefore, indexAfter, reflex))
ears.Enqueue(i);
}
// Something is wrong....no ears!
if (ears.Count == 0)
{
return null;
}
while ((Vertices.Length - removed.Count) > 3)
{
int i = ears.Dequeue();
int indexBefore = (i == 0) ? (Vertices.Length - 1) : (i - 1);
while (removed.Contains(indexBefore))
{
if (indexBefore == 0)
{
indexBefore = Vertices.Length - 1;
}
else indexBefore--;
}
int indexAfter = (i == Vertices.Length - 1) ? (0) : (i + 1);
while (removed.Contains(indexAfter))
{
if (indexAfter == Vertices.Length - 1)
indexAfter = 0;
else indexAfter++;
}
Triangle t = new Triangle(GetPos(Vertices[i]), GetPos(Vertices[indexBefore]), GetPos(Vertices[indexAfter]));
triangles.Add(t);
removed.Add(i);
int j = indexBefore;
int indexBeforeJ = (j == 0) ? (Vertices.Length - 1) : (j - 1);
while (removed.Contains(indexBeforeJ))
{
if (indexBeforeJ == 0)
{
indexBeforeJ = Vertices.Length - 1;
}
else indexBeforeJ--;
}
int indexAfterJ = (j == Vertices.Length - 1) ? (0) : (j + 1);
while (removed.Contains(indexAfterJ))
{
if (indexAfterJ == Vertices.Length - 1)
indexAfterJ = 0;
else indexAfterJ++;
}
int k = indexAfterJ;
int indexBeforeK = j;
int indexAfterK = (k == Vertices.Length - 1) ? (0) : (k + 1);
while (removed.Contains(indexAfterK))
{
if (indexAfterK == Vertices.Length - 1)
indexAfterK = 0;
else indexAfterK++;
}
if (reflex.Contains(j) && IsConvexVert(j, indexBeforeJ, indexAfterJ))
{
reflex.Remove(j);
convex.Add(j);
if (!ears.Contains(j) && IsEar(j, indexBeforeJ, indexAfterJ, reflex))
ears.Enqueue(j);
}
if (reflex.Contains(k) && IsConvexVert(k, indexBeforeK, indexAfterK))
{
reflex.Remove(k);
convex.Add(k);
if (!ears.Contains(k) && IsEar(k, indexBeforeK, indexAfterK, reflex))
ears.Enqueue(k);
}
}
// Add the last triangle
List<int> verts = new List<int>();
for (int i = 0; i < Vertices.Length; i++)
{
if (!removed.Contains(i))
verts.Add(i);
}
triangles.Add(new Triangle(GetPos(Vertices[verts[0]]), GetPos(Vertices[verts[1]]), GetPos(Vertices[verts[2]])));
return triangles.ToArray();
}
