I have made a few experiments playing skirmish games on isometric (actually “military perspective”) maps.
I apply a simple set of rules to roughly determine Line Of Sight:
- If two figures are at the same elevation, I just draw a line between the two and see if it meets any obstacle (at the same elevation). For instance (I) and (M) see each other, but (I) and (N) have no Line of Sight.
- If a figure is on the top of a structure, it only sees lower figures if it is near a border. For instance, (A) is not near a border and only sees (B) and (J). (D) can see (N) and (K), but cannot see (M) which is not in the direction of the nearby border.
- If a figure on the top of a structure is on the corner between two borders, it has 270 degrees visibility below. (B) sees both (O) and (M).
- If two figures are on different levels, an obstacle lower than the elevation of the higher figure blocks Line Of Sight to figures near the obstacle. For instance, (B) does not have Line Of Sight to (N), which is near to a lower building. But (B) has Line Of Sight to (K), which is behind the lower obstacle, but not near to it.
- An obstacle as high or higher than the elevation of the higher figures blocks Line Of Sight to all figures behind the obstacle (even if they are not near to it). (E) and (M) do not have Line Of Sight.
A figure near a corner benefits of cover in the 90 degrees region behind the corner. (O) has Line Of Sight to (G), but (G) is in cover.
I measure distance normally, with the exception that if the elevation distance is greater I use that instead. So, the distance between (B) and (L) is 4, even if the two figures appear to have a distance of 2.
In the following matrix, a * means that the two figures have Line Of Sight. “c” marks the cases in which figures (G) and (I) count as being in cover.