Closest distance between lines

    private ClosestLinePointResult closestDistanceBetweenLines(Vector3 a0, Vector3 a1, Vector3 b0, Vector3 b1)
    {
        //Based on https://stackoverflow.com/questions/2824478/shortest-distance-between-two-line-segments

        // Given two lines defined by (a0,a1,b0,b1)
        // Return the closest points on each segment and their distance
        //

        var result = new ClosestLinePointResult();

        // Calculate denomitator
        var A = a1 - a0;
        var B = b1 - b0;
        float magA = A.magnitude;
        float magB = B.magnitude;

        var _A = A / magA;
        var _B = B / magB;

        var cross = Vector3.Cross(_A, _B);
        var denom = cross.magnitude * cross.magnitude;


        // If lines are parallel (denom=0) test if lines overlap.
        // If they don't overlap then there is a closest point solution.
        // If they do overlap, there are infinite closest positions, but there is a closest distance
        if (denom == 0)
        {
            var d0 = Vector3.Dot(_A, (b0 - a0));

            // Overlap only possible with clamping

            var d1 = Vector3.Dot(_A, (b1 - a0));

            // Is segment B before A?
            if (d0 <= 0 && 0 >= d1)
            {
                if (Mathf.Abs(d0) < Mathf.Abs(d1))
                {
                    result.Line1Closest = a0;
                    result.Line2Closest = b0;
                    result.Distance = (a0 - b0).magnitude;

                    return result;
                }
                result.Line1Closest = a0;
                result.Line2Closest = b1;
                result.Distance = (a0 - b1).magnitude;

                return result;
            }
            // Is segment B after A?
            else if (d0 >= magA && magA <= d1)
            {
                if (Mathf.Abs(d0) < Mathf.Abs(d1))

            {
                    result.Line1Closest = a1;
                    result.Line2Closest = b0;
                    result.Distance = (a1 - b0).magnitude;

                    return result;
                }
                result.Line1Closest = a1;
                result.Line2Closest = b1;
                result.Distance = (a1 - b1).magnitude;

                return result;
            }

            // Segments overlap, return distance between parallel segments
            result.Line1Closest = Vector3.zero;
            result.Line2Closest = Vector3.zero;
            result.Distance = (((d0 * _A) + a0) - b0).magnitude;
            return result;
        }


        // Lines criss-cross: Calculate the projected closest points
        var t = (b0 - a0);
        var detA = Determinant(t, _B, cross);
        var detB = Determinant(t, _A, cross);

        var t0 = detA / denom;
        var t1 = detB / denom;

        var pA = a0 + (_A * t0); // Projected closest point on segment A
        var pB = b0 + (_B * t1); // Projected closest point on segment B


        // Clamp projections
        if (t0 < 0)
            pA = a0;
        else if (t0 > magA)
            pA = a1;

        if (t1 < 0)
            pB = b0;
        else if (t1 > magB)
            pB = b1;

        float dot;
        // Clamp projection A
        if (t0 < 0 || t0 > magA)
        {
            dot = Vector3.Dot(_B, (pA - b0));
            if (dot < 0)
                dot = 0;
            else if (dot > magB)
                dot = magB;
            pB = b0 + (_B * dot);
        }
        // Clamp projection B
        if (t1 < 0 || t1 > magB)
        {
            dot = Vector3.Dot(_A, (pB - a0));
            if (dot < 0)
                dot = 0;
            else if (dot > magA)
                dot = magA;
            pA = a0 + (_A * dot);
        }

        result.Line1Closest = pA;
        result.Line2Closest = pB;
        result.Distance = (pA - pB).magnitude;
        return result;
    }