Problem 3 Answer: "Take Cover!"

In solutions 3.1 and 3.3, the corner of A's square at which the two dotted lines converge does not cross any line connecting it to D's square, as seen in the diagrams. (Note that the endpoint touches a wall, but endpoints touching walls don't count.) Thus A has unobstructed line of sight, despite clearly being on the other side of a wall.

In solutions 3.2 and 3.4, the corner of D's square at which the two dotted lines converge itself touches a wall, so given any corner of A's square, the line from that corner to D's square will touch a wall. Remember that in problems 3.2 and 3.4, the endpoint touching a wall does count for crossing. Thus D has cover, despite having his back to the wall and there clearly being no obstructions between him and A.

This problem demonstrates that the writers of the D+D rulebook did not do a particularly good job clearly explaining the conditions for cover and line of sight.

BONUS PROBLEM: Suppose we attempt to modify the crossing condition to state that the endpoint at A's square counts for crossing, but the endpoint at D's square does not. (This would invalidate all the anomalies described in the solutions at left.) Is it still possible to find a situation in which D has cover, but no line between an interior point of A's square and an interior point of D's square crosses a wall? (Or the other way around, where D has no cover but every line between interior points crosses a wall.)