/// <summary>
/// Get the <see cref="PdfPoint"/> that is the intersection of two lines.
/// </summary>
public static PdfPoint?Intersect(this PdfLine line, PdfLine other)
{
// if the bounding boxes do not intersect, the lines cannot intersect
if (!line.GetBoundingRectangle().IntersectsWith(other.GetBoundingRectangle()))
{
return(null);
}
var eq1 = GetSlopeIntercept(line.Point1, line.Point2);
var eq2 = GetSlopeIntercept(other.Point1, other.Point2);
if (double.IsNaN(eq1.Slope) && double.IsNaN(eq2.Slope))
{
return(null); // both lines are vertical (hence parallel)
}
if (eq1.Slope == eq2.Slope)
{
return(null); // both lines are parallel
}
var intersection = new PdfPoint();
if (double.IsNaN(eq1.Slope))
{
var x = eq1.Intercept;
var y = eq2.Slope * x + eq2.Intercept;
intersection = new PdfPoint(x, y);
}
else if (double.IsNaN(eq2.Slope))
{
var x = eq2.Intercept;
var y = eq1.Slope * x + eq1.Intercept;
intersection = new PdfPoint(x, y);
}
else
{
var x = (eq2.Intercept - eq1.Intercept) / (eq1.Slope - eq2.Slope);
var y = eq1.Slope * x + eq1.Intercept;
intersection = new PdfPoint(x, y);
}
// check if the intersection point belongs to both segments
// (for the moment we only know it belongs to both lines)
if (!line.Contains(intersection))
{
return(null);
}
if (!other.Contains(intersection))
{
return(null);
}
return(intersection);
}