public static bool IsInsideTriangle(Coords2D _xyA, Coords2D _xyB, Coords2D _xyC, Coords2D _xy, bool _check_triangle = false)
{
if (_check_triangle)
{
if (!Coords2D.InGeneralPosition(_xyA, _xyB, _xyC))
{
return(false);
}
}
if (_xyA == null || _xyB == null || _xyC == null)
{
return(false);
}
double diff_xA = _xy.X - _xyA.X;
double diff_xB = _xy.X - _xyB.X;
double diff_xC = _xy.X - _xyC.X;
bool inside_x = (Math.Sign(diff_xA) != Math.Sign(diff_xB)) || (Math.Sign(diff_xA) != Math.Sign(diff_xC));
double diff_yA = _xy.Y - _xyA.Y;
double diff_yB = _xy.Y - _xyB.Y;
double diff_yC = _xy.Y - _xyC.Y;
bool inside_y = (Math.Sign(diff_yA) != Math.Sign(diff_yB)) || (Math.Sign(diff_yA) != Math.Sign(diff_yC));
return(inside_x && inside_y);
}
public static bool InGeneralPosition(Coords2D _xy1, Coords2D _xy2, Coords2D _xy3)
{
return(Coords2D.InGeneralPosition(_xy1, _xy2) &&
Coords2D.InGeneralPosition(_xy2, _xy3) &&
Coords2D.InGeneralPosition(_xy3, _xy1));
}
private static double Interpolate2D(Coords2D _xy, Dictionary <Coords2D, double> _Fxy)
{
if (_Fxy == null || _Fxy.Count < 3)
{
return(double.NaN);
}
// find closest xy values
SortedList <double, Coords2D> distances = new SortedList <double, Coords2D>();
foreach (Coords2D xy_current in _Fxy.Keys)
{
double dist = Math.Abs(_xy.X - xy_current.X) + Math.Abs(_xy.Y - xy_current.Y);
distances.Add(dist, xy_current);
}
// construct the smallest well-defined triangle containing _xy
Coords2D xyA = distances.ElementAt(0).Value;
Coords2D xyB = distances.ElementAt(1).Value;
int i = 1;
if (!Coords2D.InGeneralPosition(xyA, xyB))
{
for (; i < distances.Count; i++)
{
xyB = distances.ElementAt(i).Value;
if (Coords2D.InGeneralPosition(xyA, xyB))
{
break;
}
}
}
if (!Coords2D.InGeneralPosition(xyA, xyB))
{
return(double.NaN);
}
Coords2D xyC = null;
for (int j = 1; j < distances.Count && j != i; j++)
{
xyC = distances.ElementAt(j).Value;
if (Coords2D.InGeneralPosition(xyA, xyB, xyC) && Coords2D.IsInsideTriangle(xyA, xyB, xyC, _xy, false))
{
break;
}
}
if (!Coords2D.InGeneralPosition(xyA, xyB, xyC) || !Coords2D.IsInsideTriangle(xyA, xyB, xyC, _xy, false))
{
return(double.NaN);
}
// perform actual interpolation
double a, b, c;
Coords2D.GetBarycentricCoords(xyA, xyB, xyC, _xy, out a, out b, out c);
if (double.IsNaN(a) || double.IsNaN(b) || double.IsNaN(c))
{
return(double.NaN);
}
return(a * _Fxy[xyA] + b * _Fxy[xyB] + c * _Fxy[xyC]);
}