public override bool Intersects(GeoLine line, out GeoPoint intersection1, out GeoPoint intersection2, out int intersections)
{
intersection1 = new GeoPoint(float.NaN, float.NaN);
intersection2 = new GeoPoint(float.NaN, float.NaN);
const Double increment = .1;
bool intersects = false;
GeoPoint p = line.P1.Clone() as GeoPoint;
do
{
if (this.Contains(p))
{
intersects = true;
break;
}
p = EarthGeo.GetPoint(p, line.Bearing, increment);
} while(EarthGeo.GetDistance(line.P1 as GeoPoint, p) < line.Length);
intersections = 0;
if (intersects)
{
Double degy = EarthGeo.DegreesPerMeterAtLatitude(_center.Latitude);
Double degx = EarthGeo.DegreesPerMeterAtLongitude(_center.Longitude);
Double radius = Radius * Math.Max(degx, degy);
Double dx, dy, A, B, C, det, t;
dx = line.P2.X - line.P1.X;
dy = line.P2.Y - line.P1.Y;
A = dx * dx + dy * dy;
B = 2 * (dx * (line.P1.X - Center.X) + dy * (line.P1.Y - Center.Y));
C = (line.P1.X - Center.X) * (line.P1.X - Center.X) + (line.P1.Y - Center.Y) * (line.P1.Y - Center.Y) - radius * radius;
det = B * B - 4 * A * C;
if ((A <= 0.00000001) || (det < 0))
{
// No real solutions.
intersection1 = new GeoPoint(float.NaN, float.NaN);
intersection2 = new GeoPoint(float.NaN, float.NaN);
}
else if (det == 0)
{
// One solution.
t = -B / (2 * A);
intersection1 = new GeoPoint(line.P1.X + t * dx, line.P1.Y + t * dy);
intersection2 = new GeoPoint(float.NaN, float.NaN);
intersections = 1;
}
else
{
// Two solutions.
t = (float)((-B + Math.Sqrt(det)) / (2 * A));
intersection1 = new GeoPoint(line.P1.X + t * dx, line.P1.Y + t * dy);
t = (float)((-B - Math.Sqrt(det)) / (2 * A));
intersection2 = new GeoPoint(line.P1.X + t * dx, line.P1.Y + t * dy);
intersections = 2;
}
}
return(intersects);
}
