public Intersection(Line line1, Line line2, float minRatio)
{
this.Line1 = line1;
this.Line2 = line2;
//https://en.wikipedia.org/wiki/Line–line_intersection
float x1 = Line1.Point1.X;
float y1 = Line1.Point1.Y;
float x2 = Line1.Point2.X;
float y2 = Line1.Point2.Y;
float x3 = Line2.Point1.X;
float y3 = Line2.Point1.Y;
float x4 = Line2.Point2.X;
float y4 = Line2.Point2.Y;
float denominator = (x1 - x2) * (y3 - y4) - (y1 - y2) * (x3 - x4);
if (denominator == 0.0)
{
Exists = false;
return;
}
float t = ((x1 - x3) * (y3 - y4) - (y1 - y3) * (x3 - x4)) / denominator;
if (t < 0 || t > 1)
{
Exists = false;
return;
}
float u = -((x1 - x2) * (y1 - y3) - (y1 - y2) * (x1 - x3)) / denominator;
if (u < 0 || u > 1)
{
Exists = false;
return;
}
Exists = true;
Point intersection = new Point();
intersection.X = (int)Math.Round(x1 + t * (x2 - x1));
intersection.Y = (int)Math.Round(y1 + t * (y2 - y1));
this.Point = intersection;
if (intersection == line1.Point1 || intersection == line1.Point2 || intersection == line2.Point1 || intersection == line2.Point2)
{
Exists = false;
return;
}
if (minRatio == 0.0)
{
return;
}
float distanceToIntersection = Convert.ToSingle(Math.Sqrt(Math.Pow(x1 - intersection.X, 2) + Math.Pow(y1 - intersection.Y, 2)));
float ratio = distanceToIntersection / Line1.Length();
if (ratio < minRatio || ratio > 1 - minRatio)
{
Exists = false;
return;
}
distanceToIntersection = Convert.ToSingle(Math.Sqrt(Math.Pow(x3 - intersection.X, 2) + Math.Pow(y3 - intersection.Y, 2)));
ratio = distanceToIntersection / Line2.Length();
if (ratio < minRatio || ratio > 1 - minRatio)
{
Exists = false;
}
}