3.7. Lighting

| Chapter 3: Place |

| 3.7. Lighting

At any place (room, or inside a container) light is either fully present or fully absent. Inform does not usually try to track intermediate states of lighting, but see The Undertomb 2 for a single lantern with varying light levels and Zorn of Zorna for multiple candles that can be lit for cumulative changes to the light level.

Light can be added to, but not taken away: rooms and things can act as sources of light, by having the "lighted" and "lit" properties respectively, but they cannot be sinks which drain light away. The reason darkness is not a constant hazard in Inform-written games is that rooms always have the "lighted" property unless declared "dark". (We assume daylight or some always-on electric lighting.) A "dark" room may well still be illuminated if a light source happens to be present:

> The Deep Crypt is a dark room. The candle lantern is a lit thing in the Deep Crypt.

Hymenaeus allows us to explicitly refer to torches as "lit" or "unlit", or (as synonyms) "flaming" or "extinguished".

For light produced electrically we might want a wall switch, as in Down Below, or a portable lamp, as in The Dark Ages Revisited.

The fierce, locally confined light thrown out by a carried lamp has a quality quite unlike weak but ambient daylight, and Reflections exploits this to make a lantern feel more realistic.

When the player experiences darkness in a location, Inform is usually very guarded in what it reveals. ("It is pitch dark, and you can't see a thing.") Hohmann Transfer gives darkness a quite different look, and Four Stars heightens the other senses so that a player in darkness can still detect her surroundings. The first of the two examples in Peeled allows exploration of a dark place by touch.

It is sometimes useful to check whether a room that is not the current location happens to contain a light source or be naturally lighted. This poses a few challenges. Unblinking demonstrates one way of doing this, so long as there are no backdrop light sources.

Cloak of Darkness is a short and sweet game based on a light puzzle.

See Room Descriptions for an item that can only be seen in bright light, when an extra lamp is switched on

See Looking Under and Hiding for a looking under action which is helped by the fiercer brightness of a light source

See Going, Pushing Things in Directions for making it hazardous to walk around in the dark

See Electricity and Magnetism for batteries to power a torch or flashlight

See Fire for a non-electrical way to produce light

49
| Example The Undertomb 2 Flickering lantern-light effects added to the Undertomb. |
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333
| Example Zorn of Zorna Light levels vary depending on the number of candles the player has lit, and this determines whether or not he is able to examine detailed objects successfully. |
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"Zorn of Zorna" Visibility rule: if examining: if the detail of the noun is fine and the number of visible lit candles is less than 5, there is insufficient light; if the detail of the noun is ordinary and the number of visible lit candles is less than 3, there is insufficient light; there is sufficient light. Detail is a kind of value. The details are fine, ordinary, and gross. A thing has detail. A candle is a kind of thing. Before printing the name of a candle while not burning or blowing out: say "[if lit]lit [otherwise]unlit [end if]". A candle is usually lit. Before printing the plural name of a candle while not burning or blowing out: say "[if lit]lit [otherwise]unlit [end if]". A candle is usually lit. Understand the lit property as describing a candle. A candle is usually gross. Instead of burning a candle: now the noun is lit; say "You light [the noun]." Understand "blow out [something]" or "extinguish [something]" or "put out [something]" as blowing out. Understand the command "snuff" as "extinguish". Blowing out is an action applying to one thing. Understand "burn [unlit candle]" as burning. Instead of blowing out a candle: now the noun is unlit; say "You put out [the noun]." Rule for printing a refusal to act in the dark: if we are examining something, say "The details of [the noun] are too fine to make out in the light of only [the number of visible lit candles in words] candle[s]." instead. Every turn when the Todal is visible: if the number of visible lit candles is greater than 1: say "The brightness of the room wakens the Todal from slumber, and with you unarmed..."; end the story; otherwise: say "Todal sleeps fitfully, troubled by even that faint light." A room is usually dark. The Palace is a room. "The Duke is out; the way is clear. East is Saralinda's Chamber; north, a hallway zigs and zags down to the gate that leads out." A finely-written placard is in the Palace. "A finely-written placard is on the wall next to this exit." The placard is fine. The description of the placard is "You read: 'Beware the Todal: its bite is worse than its gleep. No more than one candle!'" The candle-stand is a supporter in the Palace. Understand "stand" as the candle-stand. The description of the candle-stand is "The candle-stand is a tall metal branch for holding lights, but someone has quite practically added casters to the bottom." It is pushable between rooms. Three candles are on the candle-stand. Instead of removing something from the candle-stand: say "[The noun] is fixed quite firmly in place." Instead of taking something which is on the candle-stand: say "[The noun] won't come out of the holder." Instead of putting something on the candle-stand: say "[The candle-stand] is full." Saralinda's Chamber is east of the Palace. "Now that Saralinda herself is gone, there is no real radiance in this place." Two unlit candles are in Saralinda's Chamber. A large-print romantic novel is in Saralinda's Chamber. The novel is ordinary. The description of the novel is "'She Was Only The Chimney-Sweep's Daughter', by Marie Swelldon." The Zig-Zag Hallway is north of the Palace. "The Hallway goes left, then right, then left again..." Two unlit candles are in the Hallway. Todal is an animal in the Zig-Zag Hallway. Rule for printing the description of a dark room when the Todal is in the location: try listening. Instead of listening when in darkness and the Todal is in the location: say "In the darkness something softly gleeps." Instead of going north from the Hallway when in darkness: say "You stumble and cannot find your way." North of the Hallway is Freedom. Instead of going to Freedom: say "You make it out into the cool night air at last!"; end the story finally. Test me with "examine placard / get placard / n / listen / n / s / examine candle-stand / push candle-stand east / examine novel / get unlit candle / light it / light unlit candle / examine placard / push candle-stand west / e / examine novel / w / n / n".

301
| Example Hymenaeus Understanding "flaming torch" and "extinguished torch" to refer to torches when lit and unlit. |
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25
| Example Down Below A light switch which makes the room it is in dark or light. |
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194
| Example The Dark Ages Revisited An electric light kind of device which becomes lit when switched on and dark when switched off. |
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338
| Example Reflections Emphasizing the reflective quality of shiny objects whenever they are described in the presence of the torch. |
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334
| Example Hohmann Transfer Changing the way dark rooms are described to avoid the standard Inform phrasing. |
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335
| Example Four Stars An elaboration of the idea that when light is absent, the player should be given a description of what he can smell and hear, instead. |
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350
| Example Peeled Two different approaches to adjusting what the player can interact with, compared. |
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81
| Example Unblinking Finding a best route through light-filled rooms only, leaving aside any that might be dark. |
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280
| Example Cloak of Darkness Implementation of "Cloak of Darkness", a simple example game that for years has been used to demonstrate the features of IF languages. |
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