/// <summary>
/// The validate method check if the XYPolyline is valid. The checks
/// made are:
/// - is number of points >= 3
/// - is the length of all line segments positiv
/// - do any lines cross
/// - is the area positiv
/// Exception is raised if the constraints are not met.
/// </summary>
public new void Validate()
{
if (Points.Count < 3)
{
throw new System.Exception("Number of vertices in polygon element is less than 3.");
}
if (GetArea() <= 0)
{
throw new System.Exception("Area of polygon is negative or zero. XYPolygons must be ordered counter clockwise.");
}
for (int j = 0; j < Points.Count; j++)
{
if (GetLine(j).GetLength() == 0)
{
throw new System.Exception("Length of line segment no: " +
j.ToString() + " (0-based) of XYPolygon is zero.");
}
}
for (int j = 0; j < Points.Count; j++)
{
for (int m = 0; m < j; m++)
{
if (XYGeometryTools.DoLineSegmentsIntersect(GetLine(j), GetLine(m)))
{
throw new System.Exception("Line no: " + j.ToString() + " and line no: " +
m.ToString() + " of XYPolygon crosses.");
}
}
}
}
/// <summary>
/// The method decides if the triangle formed by P(i-1), P(i) and
/// P(i+1) from Polygon are intersected by any of the other points
/// of the polygon.
/// </summary>
/// <param name="i">Middle index for the three points that forms the triangle</param>
/// <returns>
/// <p>true: If the triangle P(i-1), P(i), P(i+1) is intersected by other parts of Polygon</p>
/// <p>false: otherwise</p>
/// </returns>
protected bool IsIntersected(int i)
{
double x = 0;
double y = 0;
int n = Points.Count;
int im1 = i - 1;
int ip1 = i + 1;
if (i == 0)
{
im1 = n - 1;
}
else if (i == n - 1)
{
ip1 = 0;
}
XYPoint nodeim1 = new XYPoint((XYPoint)Points[im1]);
XYPoint nodei = new XYPoint((XYPoint)Points[i]);
XYPoint nodeip1 = new XYPoint((XYPoint)Points[ip1]);
XYPolygon localPolygon = new XYPolygon();
localPolygon.Points.Add(nodeim1);
localPolygon.Points.Add(nodei);
localPolygon.Points.Add(nodeip1);
int j = 0;
bool intersected = false;
while (((j < n - 1) && (!intersected)))
{
x = ((XYPoint)Points[j]).X;
y = ((XYPoint)Points[j]).Y;
if (((((j != im1) && (j != i)) && (j != ip1)) && XYGeometryTools.IsPointInPolygon(x, y, localPolygon)))
{
return(true);
}
else
{
j++;
}
}
return(false);
}
