public void CutEar()
{
RegionPolygon polygon = new RegionPolygon(m_aUpdatedPolygonVertices);
bool bFinish = false;
//if (polygon.GetPolygonType()==PolygonType.Convex) //don't have to cut ear
// bFinish=true;
if (m_aUpdatedPolygonVertices.Length == 3) //triangle, don't have to cut ear
{
bFinish = true;
}
LatLng pt = new LatLng();
while (bFinish == false) //UpdatedPolygon
{
int i = 0;
bool bNotFound = true;
while (bNotFound &&
(i < m_aUpdatedPolygonVertices.Length)) //loop till find an ear
{
pt = m_aUpdatedPolygonVertices[i];
if (IsEarOfUpdatedPolygon(pt))
{
bNotFound = false; //got one, pt is an ear
}
else
{
i++;
}
} //bNotFount
//An ear found:}
if (pt != null)
{
UpdatePolygonVertices(pt);
}
polygon = new RegionPolygon(m_aUpdatedPolygonVertices);
//if ((polygon.GetPolygonType()==PolygonType.Convex)
// && (m_aUpdatedPolygonVertices.Length==3))
if (m_aUpdatedPolygonVertices.Length == 3)
{
bFinish = true;
}
} //bFinish=false
SetPolygons();
}
/****************************************************************
* 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(LatLng vertex)
{
RegionPolygon polygon = new RegionPolygon(m_aUpdatedPolygonVertices);
if (polygon.Vertices.PolygonVertex(vertex))
{
bool bEar = true;
if (polygon.Vertices.PolygonVertexType(vertex) == PolygonType.Convex)
{
LatLng pi = vertex;
LatLng pj = polygon.Vertices.PreviousPoint(vertex); //previous vertex
LatLng pk = polygon.Vertices.NextPoint(vertex); //next vertex
for (int i = m_aUpdatedPolygonVertices.GetLowerBound(0);
i < m_aUpdatedPolygonVertices.GetUpperBound(0); i++)
{
LatLng pt = m_aUpdatedPolygonVertices[i];
if (!(pt.EqualsPoint(pi) || pt.EqualsPoint(pj) || pt.EqualsPoint(pk)))
{
if (TriangleContainsPoint(new LatLng[] { 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;
{
System.Diagnostics.Trace.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(LatLng vertex)
{
ArrayList alTempPts = new ArrayList();
for (int i = 0; i < m_aUpdatedPolygonVertices.Length; i++)
{
if (vertex.EqualsPoint(
m_aUpdatedPolygonVertices[i])) //add 3 pts to FEars
{
RegionPolygon polygon = new RegionPolygon(m_aUpdatedPolygonVertices);
LatLng pti = vertex;
LatLng ptj = polygon.Vertices.PreviousPoint(vertex); //previous point
LatLng ptk = polygon.Vertices.NextPoint(vertex); //next point
LatLng[] aEar = new LatLng[3]; //3 vertices of each ear
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 LatLng[nLength - 1];
for (int i = 0; i < alTempPts.Count; i++)
{
m_aUpdatedPolygonVertices[i] = (LatLng)alTempPts[i];
}
}
}
