/// <summary>
/// Calculates the intersection between two line segments.
/// </summary>
/// <param name="a">The first line segment.</param>
/// <param name="b">The segment line segment.</param>
/// <param name="intersectionFound">Whether or not the lines intersect.</param>
/// <returns>The point of intersection between the two given line segments.</returns>
public static DoublePoint CalculateLineIntersection(DoubleLine a, DoubleLine b, out bool intersectionFound)
{
// Calculate the determinant's denominator
var denominator = (a._start.X - a._end.X) * (b._start.Y - b._end.Y) -
(a._start.Y - a._end.Y) * (b._start.X - b._end.X);
if (denominator != 0)
{
// Calculate the determinants
var xDeterminant = ((a._start.X * a._end.Y - a._start.Y * a._end.X) * (b._start.X - b._end.X) -
(a._start.X - a._end.X) * (b._start.X * b._end.Y - b._start.Y * b._end.X)) /
denominator;
var yDeterminant = ((a._start.X * a._end.Y - a._start.Y * a._end.X) * (b._start.Y - b._end.Y) -
(a._start.Y - a._end.Y) * (b._start.X * b._end.Y - b._start.Y * b._end.X)) /
denominator;
// Ensure that the intersection point actually lies within both line segments
if (MathUtils.AlmostGreaterThanOrEqual(xDeterminant, Math.Min(a._start.X, a._end.X)) &&
MathUtils.AlmostLessThanOrEqual(xDeterminant, Math.Max(a._start.X, a._end.X)) &&
MathUtils.AlmostGreaterThanOrEqual(xDeterminant, Math.Min(b._start.X, b._end.X)) &&
MathUtils.AlmostLessThanOrEqual(xDeterminant, Math.Max(b._start.X, b._end.X)) &&
MathUtils.AlmostGreaterThanOrEqual(yDeterminant, Math.Min(a._start.Y, a._end.Y)) &&
MathUtils.AlmostLessThanOrEqual(yDeterminant, Math.Max(a._start.Y, a._end.Y)) &&
MathUtils.AlmostGreaterThanOrEqual(yDeterminant, Math.Min(b._start.Y, b._end.Y)) &&
MathUtils.AlmostLessThanOrEqual(yDeterminant, Math.Max(b._start.Y, b._end.Y))
)
{
intersectionFound = true;
return(new DoublePoint(xDeterminant, yDeterminant));
}
}
// If the denominator came out to 0 or the point isn't within both
// line segments, then the lines don't intersect
intersectionFound = false;
return(new DoublePoint(0, 0));
}
