public static double Distance(ICoordinates point1, ICoordinates point2)
{
return Coordinates.Sub(point2, point1).Module;
}
internal static PointsAtDistanceSolution GetPointsAtDistance(Line2 first, Coordinates second, double distance)
{
//check that line is not too far
if (Distance(second, first) > distance)
{
return new PointsAtDistanceSolution(SolutionType.None);
}
else
{
//check if point belong to line
if (first.CheckPoint(second))
{
return new PointsAtDistanceSolution(SolutionType.Specific, new List<Tuple<Coordinates, Coordinates>>() { new Tuple<Coordinates, Coordinates>(Coordinates.Add(second, first.Versor * distance), second), new Tuple<Coordinates, Coordinates>(Coordinates.Sub(second, first.Versor * distance), second) });
}
else
{
Coordinates p1 = Coordinates.Zero;
Coordinates p2 = Coordinates.Zero;
if (first.B == 0)
{
double T1 = -first.C / first.A - second.X;
double T2 = Math.Sqrt((distance - T1) * (distance + T1));
p1.X = -first.C / first.A;
p1.Y = second.Y + T2;
p2.X = -first.C / first.A;
p2.Y = second.Y - T2;
}
else
{
double T1 = second.X + first.M * (second.Y - first.Q);
double T2 = 1 + Math.Pow(first.M, 2);
double T3 = Math.Sqrt(T2 * Math.Pow(distance, 2) - Math.Pow(first.M * second.X - second.Y + first.Q, 2));
p1.X = (T1 + T3) / T2;
p1.Y = p1.X * first.M + first.Q;
p2.X = (T1 - T3) / T2;
p2.Y = p2.X * first.M + first.Q;
}
return new PointsAtDistanceSolution(SolutionType.Specific, new List<Tuple<Coordinates, Coordinates>>() { new Tuple<Coordinates, Coordinates>(p1, second), new Tuple<Coordinates, Coordinates>(p2, second) });
}
}
}
