/// <summary>
/// Get the parametres of the points on line segment. (between 0 t0 1)
/// </summary>
/// <param name="point">the point.</param>
/// <returns>the parametre of the point on line segment.</returns>
public double GetPosition(Point2D point)
{
if (point == FirstPoint)
{
return(0);
}
else if (point == LastPoint)
{
return(1);
}
else
{
Vector2D v1 = point - FirstPoint;
Vector2D v2 = this.ToVector();
double d = Vector2D.Determinant(v1, v2);
if (d < ZeroTolerance)
{
return(v1.Length / v2.Length);
}
else if (d >= ZeroTolerance)
{
return(double.PositiveInfinity);
}
else
{
return(double.NegativeInfinity);
}
}
}
/// <summary>
/// Whether the point is on the line.
/// </summary>
/// <param name="point">the point.</param>
/// <returns>true if is on the line.</returns>
public bool isOnLine(Point2D point)
{
if (point == FirstPoint || point == LastPoint)
{
return(true);
}
else
{
Vector2D v1 = point - FirstPoint;
Vector2D v2 = LastPoint - point;
return(Vector2D.Determinant(v1, v2) < ZeroTolerance);
}
}
/// <summary>
/// Whether the line segment contains the point and the point is not on the terminal.
/// </summary>
/// <param name="point">the point.</param>
/// <returns>true if truly contains.</returns>
public bool TrulyContains(Point2D point)
{
Vector2D v1 = point - FirstPoint;
Vector2D v2 = LastPoint - point;
double d1 = v1 * v2;
double d2 = Vector2D.Determinant(v1, v2);
if ((d1 > ZeroTolerance) && Math.Abs(d2) < ZeroTolerance)
{
return(true);
}
else
{
return(false);
}
}