private static bool PointOnLineSSI(DBLV A, DBLV B, DBLV point)
{
bool onX = (point.X >= Math.Min(A.X, B.X) && point.X <= Math.Max(A.X, B.X)) || FloatHelp.ApproxEquals(point.X, A.X, .001) || FloatHelp.ApproxEquals(point.X, B.X, .001);
bool onY = (point.Y >= Math.Min(A.Y, B.Y) && point.Y <= Math.Max(A.Y, B.Y)) || FloatHelp.ApproxEquals(point.Y, A.Y, .001) || FloatHelp.ApproxEquals(point.Y, B.Y, .001);
return(onX && onY);
}
private static DBLV ConvertToSI(DBLV A, DBLV B)
{
double slope = (B.Y - A.Y) / (B.X - A.X);
double intersect = A.Y + (-A.X * slope);
return(new DBLV(slope, intersect));
}
public override bool Equals(object obj)
{
if (obj is DBLV)
{
DBLV other = (DBLV)obj;
return(other.X == X && other.Y == Y);
}
return(false);
}
public static ColisionInfo LinesIntersect(Vector2 Atmp, Vector2 Btmp, Vector2 Ctmp, Vector2 Dtmp)
{
DBLV A = new DBLV(Atmp), B = new DBLV(Btmp), C = new DBLV(Ctmp), D = new DBLV(Dtmp);
DBLV line1 = ConvertToSI(A, B);
DBLV line2 = ConvertToSI(C, D);
// Coterminal?
if (line1.Equals(line2))
{
if (PointOnLineSSI(A, B, C) || PointOnLineSSI(A, B, D))
{
// C -> D -> B
DBLV Colision1 = (PointOnLineSSI(A, B, C) ? C : (PointOnLineSSI(A, B, D) ? D : B));
// A -> B -> D
DBLV Colision2 = (PointOnLineSSI(C, D, A) ? A : (PointOnLineSSI(C, D, B) ? B : D));
return(new ColisionInfo(true, 2, Colision1, Colision2));
}
return(new ColisionInfo(false, 0, null));
}
DBLV pointOfIntersection = new DBLV();
if (!double.IsInfinity(line1.X) && !double.IsInfinity(line2.X))
{
pointOfIntersection.X = (line1.Y - line2.Y) / (line2.X - line1.X);
pointOfIntersection.Y = (line1.X * pointOfIntersection.X) + line1.Y;
}
else if (!double.IsInfinity(line2.X))
{
pointOfIntersection.X = A.X;
pointOfIntersection.Y = (line2.X * pointOfIntersection.X) + line2.Y;
}
else if (!double.IsInfinity(line1.X))
{
pointOfIntersection.X = C.X;
pointOfIntersection.Y = (line1.X * pointOfIntersection.X) + line1.Y;
}
if (PointOnLineSSI(A, B, pointOfIntersection) && PointOnLineSSI(C, D, pointOfIntersection))
{
if (pointOfIntersection.ApproxEquals(A, .001) || pointOfIntersection.ApproxEquals(B, .001) || pointOfIntersection.ApproxEquals(C, .001) || pointOfIntersection.ApproxEquals(D, .001))
{
return(new ColisionInfo(true, 1, pointOfIntersection));
}
return(new ColisionInfo(true, 3, pointOfIntersection));
}
return(new ColisionInfo(false, 0, null));
}
public bool ApproxEquals(DBLV obj, double margin)
{
return(FloatHelp.ApproxEquals(this, obj, margin));
}
public static bool ApproxEquals(DBLV A, DBLV B, double margin)
{
return(Math.Abs(A.X - B.X) < margin && Math.Abs(A.Y - B.Y) < margin);
}
private static bool PointOnLineSSI(DBLV A, DBLV B, DBLV point)
{
return(point.X >= Math.Min(A.X, B.X) && point.X <= Math.Max(A.X, B.X) && point.Y >= Math.Min(A.Y, B.Y) && point.Y <= Math.Max(A.Y, B.Y));
}
