Canguro.Controller.Snap.SnapController.createIntersection C# (CSharp) Method

        private PointMagnet createIntersection(LineMagnet l1, LineMagnet l2, GraphicView activeView, System.Windows.Forms.MouseEventArgs e)
        {
            if (l1 != null && l2 != null)
            {
                float numer, denom;
                float d1, d2, d3, d4, d5;
                Vector3 p13 = l1.Position - l2.Position;
                Vector3 p21 = l1.Direction;
                Vector3 p43 = l2.Direction;

                d1 = p13.X * p43.X + p13.Y * p43.Y + p13.Z * p43.Z;
                d2 = p43.X * p21.X + p43.Y * p21.Y + p43.Z * p21.Z;
                d3 = p13.X * p21.X + p13.Y * p21.Y + p13.Z * p21.Z;
                d4 = p43.X * p43.X + p43.Y * p43.Y + p43.Z * p43.Z;
                d5 = p21.X * p21.X + p21.Y * p21.Y + p21.Z * p21.Z;

                denom = d5 * d4 - d2 * d2;
                if (Math.Abs(denom) < float.Epsilon)
                    return null;
                numer = d1 * d2 - d3 * d4;

                float r = numer / denom;
                float s = (d1 + d2 * r) / d4;

                Vector3 pa = l1.Position + Vector3.Scale(p21, r);
                Vector3 pb = l2.Position + Vector3.Scale(p43, s);

                if ((pa - pb).Length() > 0.0001)
                    return null;

                // Create magnet
                PointMagnet intPtMagnet = new PointMagnet(pa,
                    PointMagnetType.Intersection);

                if (intPtMagnet.Snap(activeView, e.Location) < SnapViewDistance)
                {
                    intPtMagnet.RelatedMagnets.Add(l1);
                    intPtMagnet.RelatedMagnets.Add(l2);
                    return intPtMagnet;
                }
            }

            return null;
        }