/// <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)); }