private static bool LineLine(LineLike a, LineLike b, bool aSeg, bool bSeg, out Vector[] intersects)
{
// https://en.wikipedia.org/wiki/Line–line_intersection
var x1 = a.P1.X;
var y1 = a.P1.Y;
var x2 = a.P2.X;
var y2 = a.P2.Y;
var x3 = b.P1.X;
var y3 = b.P1.Y;
var x4 = b.P2.X;
var y4 = b.P2.Y;
var nume0 = x1 * y2 - y1 * x2;
var nume1 = x3 * y4 - y3 * x4;
var xNume = nume0 * (x3 - x4) - (x1 - x2) * nume1;
var yNume = nume0 * (y3 - y4) - (y1 - y2) * nume1;
// equals to (a.P1 - a.P2).Cross(b.P1 - b.P2);
var deno = (x1 - x2) * (y3 - y4) - (y1 - y2) * (x3 - x4);
var tNume = (x1 - x3) * (y3 - y4) - (y1 - y3) * (x3 - x4);
var uNume = (x1 - x2) * (y1 - y3) - (y1 - y2) * (x1 - x3);
if (deno == 0)
{
intersects = null;
return(false);
}
var t = tNume / deno;
var u = -uNume / deno;
if (aSeg)
{
if (t < 0 || 1 < t)
{
intersects = default;
return(false);
}
}
if (bSeg)
{
if (u < 0 || 1 < u)
{
intersects = default;
return(false);
}
}
intersects = new[] { new Vector(xNume / deno, yNume / deno) };
return(true);
}
public bool Perpendicular(LineLike other, float tolerance = 0.0001f)
{
return((P1 - P2).Dot(other.P1 - other.P2) < tolerance);
}