// https://stackoverflow.com/a/565282/3333753
static public bool Intersects(this Segment segmentA, Segment segmentB, out Segment?intersection)
{
Vector2 vectorA = segmentA.Vector;
Vector2 vectorB = segmentB.Vector;
Vector2 p0Diff = segmentB.P0 - segmentA.P0;
float b = p0Diff.Cross(vectorB);
float abCross = vectorA.Cross(vectorB);
// Check if segments are parallel
if (abCross.EqualsZero())
{
// Check if segments are colinear
if (b.EqualsZero())
{
float aaDot = Vector2.Dot(vectorA, vectorA);
float baDot = Vector2.Dot(vectorB, vectorA);
float t0 = Vector2.Dot(p0Diff, vectorA) / aaDot;
float t1 = t0 + baDot / aaDot;
Range <float> t01 = baDot >= 0 ? new Range <float>(t0, t1) : new Range <float>(t1, t0);
// Check if segments are overlapping
if (RangeUtils.Intersects(t01, new Range <float>(0, 1)))
{
intersection = new Segment(segmentA.P0 + t01.Min * vectorA, segmentA.P0 + t01.Max * vectorA);
return(true);
}
}
}
else
{
float a = p0Diff.Cross(vectorA);
float t = a / abCross;
float u = b / abCross;
// Check if intersect at one point
if (t >= 0 && t <= 1 && u >= 0 && u <= 1)
{
Vector2 intersectionPoint = segmentA.P0 + t * vectorA;
intersection = new Segment(intersectionPoint, intersectionPoint);
return(true);
}
}
intersection = null;
return(false);
}
