Line of Sight from a vertex

A question came up last time I played. If someone begins tracing the line of sight straight from the vertex of the hex they are in and the target hex is on the line several hexes away, does that mean you you have line of sight? They measured it this way because the hexes on the line before the target allowed LOS on one side and didn't on the other side.

You can trace line of sight from any point on your hex to any point on the other hex, so you could use the side that doesn't block Line of Sight for your line.

Line of sight has to go through hexes, so you can't use the vertex itself as the line when the hexes don't allow line of sight.