/// <summary>
/// Get the t values that are the intersections of the line and the curve.
/// </summary>
/// <returns>List of t values where the <see cref="PdfPath.BezierCurve"/> and the <see cref="PdfPath.Line"/> intersect.</returns>
public static double[] FindIntersectionT(this PdfPath.BezierCurve bezierCurve, PdfPath.Line line)
{
// if the bounding boxes do not intersect, they cannot intersect
var bezierBbox = bezierCurve.GetBoundingRectangle();
if (!bezierBbox.HasValue)
{
return(null);
}
var lineBbox = line.GetBoundingRectangle();
if (!lineBbox.HasValue)
{
return(null);
}
if (!bezierBbox.Value.IntersectsWith(lineBbox.Value))
{
return(null);
}
double x1 = line.From.X;
double y1 = line.From.Y;
double x2 = line.To.X;
double y2 = line.To.Y;
return(FindIntersectionT(bezierCurve, x1, y1, x2, y2));
}
/// <summary>
/// Get the <see cref="PdfPoint"/> that is the intersection of two lines.
/// </summary>
public static PdfPoint?Intersect(this PdfPath.Line line, PdfPath.Line other)
{
// if the bounding boxes do not intersect, the lines cannot intersect
var thisLineBbox = line.GetBoundingRectangle();
if (!thisLineBbox.HasValue)
{
return(null);
}
var lineBbox = other.GetBoundingRectangle();
if (!lineBbox.HasValue)
{
return(null);
}
if (!thisLineBbox.Value.IntersectsWith(lineBbox.Value))
{
return(null);
}
var eq1 = GetSlopeIntercept(line.From, line.To);
var eq2 = GetSlopeIntercept(other.From, other.To);
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);
}