/// <summary>
/// the Quadrangle should be convex
/// </summary>
/// <param name="firstCEdge"></param>
/// <param name="intIndex"></param>
public static CEdge TriangulateQuadrangle_Delaunay(CEdge firstCEdge)
{
//the four edges constitutes a counter clockwise loop
var secondCEdge = firstCEdge.cedgeNext;
var thirdCEdge = secondCEdge.cedgeNext;
var fourthCEdge = thirdCEdge.cedgeNext;
firstCEdge.JudgeAndSetAxisAngle();
secondCEdge.JudgeAndSetAxisAngle();
thirdCEdge.JudgeAndSetAxisAngle();
fourthCEdge.JudgeAndSetAxisAngle();
CEdge newCEdge1 = new CEdge(firstCEdge.FrCpt, thirdCEdge.FrCpt);
CEdge newCEdge2 = new CEdge(firstCEdge.ToCpt, thirdCEdge.ToCpt);
newCEdge1.SetAxisAngle();
newCEdge2.SetAxisAngle();
var dblMinAngle1 = GetDividedMinAngle(newCEdge1, firstCEdge, secondCEdge, thirdCEdge, fourthCEdge);
var dblMinAngle2 = GetDividedMinAngle(newCEdge2, secondCEdge, thirdCEdge, fourthCEdge, firstCEdge);
if (dblMinAngle1 <= dblMinAngle2)
{
return(newCEdge1);
}
else
{
return(newCEdge2);
}
}
/// <summary>
///
/// </summary>
/// <param name="cedge"></param>
/// <remarks> cpt is a vertex in the CDCEL</remarks>
public static CEdge FindSmallerAxisAngleCEdgebyCEdge(CPoint cpt, CEdge cedge, bool blnAllowOverlap = false)
{
cedge.JudgeAndSetAxisAngle();
var IncidentCEdge = cpt.IncidentCEdge;
var CurrentCEdge = IncidentCEdge;
//test the first edge (IncidentCEdge)
if (CurrentCEdge.dblAxisAngle > cedge.dblAxisAngle)
{
return(CurrentCEdge.GetSmallerAxisAngleCEdge());
}
else if (CurrentCEdge.dblAxisAngle < cedge.dblAxisAngle)
{
CurrentCEdge = CurrentCEdge.GetLargerAxisAngleCEdge();
}
else
{
if (blnAllowOverlap == true)
{
return(CurrentCEdge);
}
else
{
throw new ArgumentException("edges overlap each other.");
}
}
//test other edges (IncidentCEdge)
do
{
//int intCompare = CCmpMethods.Cmp(CurrentCEdge.dblAxisAngle, cedge.dblAxisAngle);
//if (intCompare == 1)
if (CurrentCEdge.dblAxisAngle > cedge.dblAxisAngle)
{
return(CurrentCEdge.GetSmallerAxisAngleCEdge());
}
else if (CurrentCEdge.dblAxisAngle < cedge.dblAxisAngle)
{
CurrentCEdge = CurrentCEdge.GetLargerAxisAngleCEdge();
}
else
{
if (blnAllowOverlap == true)
{
return(CurrentCEdge);
}
else
{
throw new ArgumentException("edges overlap each other.");
}
}
} while (CurrentCEdge.GID != IncidentCEdge.GID);
//if cedge.dblAxisAngle is larger than the AxisAngles of all the edges,
//then the edge with largest AxisAngle is the one we are looking for
return(CurrentCEdge.GetSmallerAxisAngleCEdge());
}
