internal static bool IsParallel(Line2 first, Line2 second)
{
return first.M == second.M;
}
internal static PointsAtDistanceSolution GetPointsAtDistance(Line2 first, Line2 second, double distance)
{
//check if parallel lines
if (IsParallel(first, second))
{
//only two possible solutions:
// - parallel lines are at the correct distance => any points is a solution
// - parallel lines are not at the correct distance => no solutions
if (Distance(first, second) == distance)
{
return new PointsAtDistanceSolution(SolutionType.Any);
}
else
{
return new PointsAtDistanceSolution(SolutionType.None);
}
}
else
{
var results = new List<Tuple<Coordinates, Coordinates>>();
Coordinates p11 = Coordinates.Zero;
Coordinates p12 = Coordinates.Zero;
Coordinates p21 = Coordinates.Zero;
Coordinates p22 = Coordinates.Zero;
if (first.B == 0)
{
double T1 = -first.C / first.A * second.M + second.Q;
double T2 = Math.Sqrt(1 + Math.Pow(second.M, 2));
p11.X = -first.C / first.A;
p11.Y = T1 - distance * T2;
p12.X = -first.C / first.A;
p12.Y = T1 + distance * T2;
p21.X = (-second.M * second.Q + second.M * p11.Y + p11.X) / Math.Pow(T2, 2);
p21.Y = second.M * p21.X + second.Q;
p22.X = (-second.M * second.Q + second.M * p12.Y + p12.X) / Math.Pow(T2, 2);
p22.Y = second.M * p22.X + second.Q;
}
else if (second.B == 0)
{
p11.X = -second.C / second.A - distance;
p11.Y = first.M * p11.X + first.Q;
p12.X = -second.C / second.A + distance;
p12.Y = first.M * p12.X + first.Q;
p21.X = -second.C / second.A;
p21.Y = p11.Y;
p22.X = -second.C / second.A;
p22.Y = p12.Y;
}
else
{
double T1 = second.Q - first.Q;
double T2 = second.M - first.M;
double T3 = Math.Sqrt(1 + Math.Pow(second.M, 2));
p11.X = (-T1 + distance * T3) / T2;
p11.Y = first.M * p11.X + first.Q;
p12.X = (-T1 - distance * T3) / T2;
p12.Y = first.M * p12.X + first.Q;
p21.X = (-second.M * second.Q + second.M * p11.Y + p11.X) / Math.Pow(T3, 2);
p21.Y = second.M * p21.X + second.Q;
p22.X = (-second.M * second.Q + second.M * p12.Y + p12.X) / Math.Pow(T3, 2);
p22.Y = second.M * p22.X + second.Q;
}
return new PointsAtDistanceSolution(SolutionType.Specific, new List<Tuple<Coordinates, Coordinates>>() { new Tuple<Coordinates, Coordinates>(p11, p21), new Tuple<Coordinates, Coordinates>(p12, p22) });
}
}
internal static double Distance(Coordinates point, Line2 line)
{
return Math.Abs(point.X * line.A + point.Y * line.B + line.C) / Math.Sqrt(Math.Pow(line.A, 2) + Math.Pow(line.B, 2));
}