/**********************************************************
* To check the Pt is in the Triangle or not.
* If the Pt is in the line or is a vertex, then return true.
* If the Pt is out of the Triangle, then return false.
*
* This method is used for triangle only.
***********************************************************/
private bool TriangleContainsPoint(CPoint2D[] trianglePts, CPoint2D pt)
{
if (trianglePts.Length != 3)
{
return(false);
}
for (int i = trianglePts.GetLowerBound(0); i < trianglePts.GetUpperBound(0); i++)
{
if (pt.EqualsPoint(trianglePts[i]))
{
return(true);
}
}
bool bIn = false;
CLineSegment line0 = new CLineSegment(trianglePts[0], trianglePts[1]);
CLineSegment line1 = new CLineSegment(trianglePts[1], trianglePts[2]);
CLineSegment line2 = new CLineSegment(trianglePts[2], trianglePts[0]);
if (pt.InLine(line0) || pt.InLine(line1) ||
pt.InLine(line2))
{
bIn = true;
}
else //point is not in the lines
{
double dblArea0 = CPolygon.PolygonArea(new CPoint2D[] { trianglePts[0], trianglePts[1], pt });
double dblArea1 = CPolygon.PolygonArea(new CPoint2D[] { trianglePts[1], trianglePts[2], pt });
double dblArea2 = CPolygon.PolygonArea(new CPoint2D[] { trianglePts[2], trianglePts[0], pt });
if (dblArea0 > 0)
{
if ((dblArea1 > 0) &&
(dblArea2 > 0))
{
bIn = true;
}
}
else if (dblArea0 < 0)
{
if ((dblArea1 < 0) &&
(dblArea2 < 0))
{
bIn = true;
}
}
}
return(bIn);
}
/*******************************************************
* To cut an ear from polygon to make ears and an updated polygon:
*******************************************************/
public void CutEar()
{
CPolygon polygon = new CPolygon(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;
}
CPoint2D pt = new CPoint2D();
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 CPolygon(m_aUpdatedPolygonVertices);
//if ((polygon.GetPolygonType()==PolygonType.Convex)
// && (m_aUpdatedPolygonVertices.Length==3))
if (m_aUpdatedPolygonVertices.Length == 3)
{
bFinish = true;
}
} //bFinish=false
SetPolygons();
}
/****************************************************
* To fill m_aUpdatedPolygonVertices array with input array.
*
* m_aUpdatedPolygonVertices is a working array that will
* be updated when an ear is cut till m_aUpdatedPolygonVertices
* makes triangle (a convex polygon).
******************************************************/
private void SetUpdatedPolygonVertices()
{
int nVertices = m_aInputVertices.Length;
m_aUpdatedPolygonVertices = new CPoint2D[nVertices];
for (int i = 0; i < nVertices; i++)
{
m_aUpdatedPolygonVertices[i] = m_aInputVertices[i];
}
//m_aUpdatedPolygonVertices should be in count clock wise
if (CPolygon.PointsDirection(m_aUpdatedPolygonVertices)
== PolygonDirection.Clockwise)
{
CPolygon.ReversePointsDirection(m_aUpdatedPolygonVertices);
}
}
/*******************************************************
To cut an ear from polygon to make ears and an updated polygon:
*******************************************************/
public void CutEar()
{
CPolygon polygon = new CPolygon(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;
}
CPoint2D pt = new CPoint2D();
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 CPolygon(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(CPoint2D vertex)
{
CPolygon polygon = new CPolygon(m_aUpdatedPolygonVertices);
if (polygon.PolygonVertex(vertex))
{
bool bEar = true;
if (polygon.PolygonVertexType(vertex)
== VertexType.ConvexPoint)
{
CPoint2D pi = vertex;
CPoint2D pj = polygon.PreviousPoint(vertex); //previous vertex
CPoint2D pk = polygon.NextPoint(vertex); //next vertex
for (int i = m_aUpdatedPolygonVertices.GetLowerBound(0); i < m_aUpdatedPolygonVertices.GetUpperBound(0); i++)
{
CPoint2D pt = m_aUpdatedPolygonVertices[i];
if (!(pt.EqualsPoint(pi) || pt.EqualsPoint(pj) || pt.EqualsPoint(pk)))
{
if (TriangleContainsPoint(new CPoint2D[] { 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;
{
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(CPoint2D 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
{
CPolygon polygon = new CPolygon(m_aUpdatedPolygonVertices);
CPoint2D pti = vertex;
CPoint2D ptj = polygon.PreviousPoint(vertex); //previous point
CPoint2D ptk = polygon.NextPoint(vertex); //next point
CPoint2D[] aEar = new CPoint2D[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 CPoint2D[nLength - 1];
for (int i = 0; i < alTempPts.Count; i++)
{
m_aUpdatedPolygonVertices[i] = (CPoint2D)alTempPts[i];
}
}
}
/********************************************************
To update m_aUpdatedPolygonVertices:
Take out Vertex from m_aUpdatedPolygonVertices array, add 3 points
to the m_aEars
**********************************************************/
private void UpdatePolygonVertices(CPoint2D 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
{
CPolygon polygon = new CPolygon(m_aUpdatedPolygonVertices);
CPoint2D pti = vertex;
CPoint2D ptj = polygon.PreviousPoint(vertex); //previous point
CPoint2D ptk = polygon.NextPoint(vertex); //next point
CPoint2D[] aEar = new CPoint2D[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 CPoint2D[nLength - 1];
for (int i = 0; i < alTempPts.Count; i++) {
m_aUpdatedPolygonVertices[i] = (CPoint2D) alTempPts[i];
}
}
}
/****************************************************************
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(CPoint2D vertex)
{
CPolygon polygon = new CPolygon(m_aUpdatedPolygonVertices);
if (polygon.PolygonVertex(vertex)) {
bool bEar = true;
if (polygon.PolygonVertexType(vertex)
== VertexType.ConvexPoint) {
CPoint2D pi = vertex;
CPoint2D pj = polygon.PreviousPoint(vertex); //previous vertex
CPoint2D pk = polygon.NextPoint(vertex); //next vertex
for (int i = m_aUpdatedPolygonVertices.GetLowerBound(0); i < m_aUpdatedPolygonVertices.GetUpperBound(0); i++) {
CPoint2D pt = m_aUpdatedPolygonVertices[i];
if (!(pt.EqualsPoint(pi) || pt.EqualsPoint(pj) || pt.EqualsPoint(pk))) {
if (TriangleContainsPoint(new CPoint2D[] {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;
{
Trace.WriteLine("IsEarOfUpdatedPolygon: " + "Not a polygon vertex");
return false;
}
}