/****************************************************************
* To check whether the Vertex is an ear or not based updated Polygon vertices
*
* ref. www-cgrl.cs.mcgill.ca/~godfried/teaching/cg-projects/97/Ian
* /algorithm1.html
*
* If it is an ear, return true,
* If it is not an ear, return false;
*****************************************************************/
private bool IsEarOfUpdatedPolygon(Coordinate vertex)
{
PolygonHelper polygon = new PolygonHelper(m_aUpdatedPolygonVertices);
if (polygon.PolygonVertex(vertex))
{
bool bEar = true;
if (polygon.VertexType(vertex) == PolygonVertexType.ConvexPoint)
{
Coordinate pi = vertex;
Coordinate pj = polygon.PreviousPoint(vertex); //previous vertex
Coordinate pk = polygon.NextPoint(vertex); //next vertex
for (int i = m_aUpdatedPolygonVertices.GetLowerBound(0);
i < m_aUpdatedPolygonVertices.GetUpperBound(0); i++)
{
Coordinate pt = m_aUpdatedPolygonVertices[i];
if (!(pt.Equals(pi) || pt.Equals(pj) || pt.Equals(pk)))
{
if (TriangleContainsPoint(new Coordinate[] { pj, pi, pk }, pt))
{
bEar = false;
}
}
}
} //ThePolygon.getVertexType(Vertex)=ConvexPt
else //concave point
{
bEar = false; //not an ear/
}
return(bEar);
}
else //not a polygon vertex;
{
Debug.WriteLine("IsEarOfUpdatedPolygon: " +
"Not a polygon vertex");
return(false);
}
}
/********************************************************
* To update m_aUpdatedPolygonVertices:
* Take out Vertex from m_aUpdatedPolygonVertices array, add 3 points
* to the m_aEars
**********************************************************/
private void UpdatePolygonVertices(Coordinate vertex)
{
ArrayList alTempPts = new ArrayList();
for (int i = 0; i < m_aUpdatedPolygonVertices.Length; i++)
{
//add 3 pts to FEars
if (vertex.Equals(m_aUpdatedPolygonVertices[i]))
{
PolygonHelper polygon = new PolygonHelper(m_aUpdatedPolygonVertices);
Coordinate pti = vertex;
Coordinate ptj = polygon.PreviousPoint(vertex); //previous point
Coordinate ptk = polygon.NextPoint(vertex); //next point
//3 vertices of each ear
Coordinate[] aEar = new Coordinate[3];
aEar[0] = ptj;
aEar[1] = pti;
aEar[2] = ptk;
m_alEars.Add(aEar);
}
else
{
alTempPts.Add(m_aUpdatedPolygonVertices[i]);
} //not equal points
}
if ((m_aUpdatedPolygonVertices.Length - alTempPts.Count) == 1)
{
int nLength = m_aUpdatedPolygonVertices.Length;
m_aUpdatedPolygonVertices = new Coordinate[nLength - 1];
for (int i = 0; i < alTempPts.Count; i++)
{
m_aUpdatedPolygonVertices[i] = (Coordinate)alTempPts[i];
}
}
}
