Sight and memory

Line of sight

You see in straight lines, and line of sight works both ways: if you have a clear line to a cell, anything standing there has a clear line to you. Walls and closed doors block sight; open doors and most floor do not. Some other terrain blocks sight too, such as trees, boulders, and crags (see Terrain).

The farthest you can see is 40 cells. The edge of any radius is slightly rounded: a cell counts as within radius r when its squared distance is at most r² + r.

When you see a cell

A cell is visible when it is in line of sight, within 40 cells, and one of these is true:

• it is lit brightly enough for your eyes (your vision type sets how bright), or
• it is close enough to be seen with darkvision.

The cell you stand on is always visible.

You see a creature when you see its cell. So a creature in the dark is hidden from you unless it is within your darkvision, and a creature carrying a light shows up. You may still hear one you cannot see (see Hearing). Objects lying on a cell are seen the same way as creatures (see Objects and your pack).

Creatures see by these same rules, each with its own eyes. Standing in the dark hides you from a creature that cannot see in the dark. A lit lantern shows you to any creature that has a clear line to you and is near enough. See Creatures.

If you see floor through a narrow gap, you also see the walls around that floor, so a lit passage never appears without its walls. Such walls show only the terrain itself: no creatures or objects, and nothing beyond them. In total darkness this does not apply to your own cell, so you see only yourself.

Memory

The game remembers the terrain you have seen on each level, as you last saw it, and the piles of objects lying on it. Remembered cells are drawn dim and washed out. A door you saw open is remembered open until you see it closed. A pile is remembered as it lay when you last saw it, even if it changed since, and forgotten once you see it gone.

Memory holds terrain and objects only. You never remember creatures, effects, or the light that was there. When you look away, a creature you saw drops off the map, and remembered cells lose their light: they are simply dimmed. The faint ◌ markers of sounds you heard last only until your next turn.

The overworld is different

On the overworld sight follows the time of day, the moon, and the weather, not light. See The overworld.

See also: Vision types, Hearing, and How creatures behave.