//i didnt review this one for correctness
public LineEquation GetIntersectionWithLineForRay(Rect rectangle)
{
LineEquation intersectionLine;
if (Start == End)
{
return(null);
}
IEnumerable <LineEquation> lines = rectangle.LineSegments();
intersectionLine = new LineEquation(new Point(0, 0), new Point(0, 0));
var intersections = new Dictionary <LineEquation, Point>();
foreach (LineEquation equation in lines)
{
Point?intersectionPoint = GetIntersectionWithLineSegment(equation);
if (intersectionPoint.HasValue)
{
intersections[equation] = intersectionPoint.Value;
}
}
if (!intersections.Any())
{
return(null);
}
var intersectionPoints = new SortedDictionary <double, Point>();
foreach (var intersection in intersections)
{
if (End.IsBetweenTwoPoints(Start, intersection.Value) ||
intersection.Value.IsBetweenTwoPoints(Start, End))
{
double distanceToPoint = Start.DistanceToPoint(intersection.Value);
intersectionPoints[distanceToPoint] = intersection.Value;
}
}
if (intersectionPoints.Count == 1)
{
Point endPoint = intersectionPoints.First().Value;
intersectionLine = new LineEquation(Start, endPoint);
return(intersectionLine);
}
if (intersectionPoints.Count == 2)
{
Point start = intersectionPoints.First().Value;
Point end = intersectionPoints.Last().Value;
intersectionLine = new LineEquation(start, end);
return(intersectionLine);
}
return(null);
}
public Point?GetIntersectionWithLineSegment(LineEquation otherLine)
{
Point?intersectionPoint = GetIntersectionWithLine(otherLine);
if (intersectionPoint.HasValue &&
intersectionPoint.Value.IsBetweenTwoPoints(otherLine.Start, otherLine.End))
{
return(intersectionPoint);
}
return(default(Point?));
}
public Point?GetIntersectionWithLine(LineEquation otherLine)
{
double determinant = A * otherLine.B - otherLine.A * B;
if (determinant.IsZero()) //lines are parallel
{
return(default(Point?));
}
//Cramer's Rule
double x = (otherLine.B * C - B * otherLine.C) / determinant;
double y = (A * otherLine.C - otherLine.A * C) / determinant;
Point intersectionPoint = new Point(x, y);
return(intersectionPoint);
}