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


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** 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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* Example  Hymenaeus
Understanding "flaming torch" and "extinguished torch" to refer to torches when lit and unlit.

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"Hymenaeus"

A torch is kind of thing. Understand the lit property as describing a torch. Understand "lighted" or "flaming" or "burning" as lit. Understand "extinguished" as unlit. A torch is usually lit.

Before printing the name of a lit torch, say "flaming ".
Before printing the name of an unlit torch, say "extinguished ".

The Wedding Procession is a room.

Orpheus is a man in the Wedding Procession. Orpheus carries a torch.
Eurydice is a woman in the Wedding Procession. Eurydice carries a torch.

Rule for writing a paragraph about someone (called target):
    say "[The target] carries [a list of things carried by the target]."

Every turn:
    if a random chance of 1 in 2 succeeds and a torch is lit:
        let target torch be a random lit torch;
        now the target torch is unlit;
        say "Aquilo blows down from the north, extinguishing the torch carried by [the holder of the target torch]."

Instead of examining a lit torch:
    say "It casts a bright glow over [the holder of the noun]."
Instead of examining an unlit torch:
    say "[The holder of the noun] is looking at it disconsolately, obviously worried about the omens."

Test me with "z / z / z / look / x flaming torch / x extinguished torch".

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** Example  Down Below
A light switch which makes the room it is in dark or light.

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* 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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* Example  Reflections
Emphasizing the reflective quality of shiny objects whenever they are described in the presence of the torch.

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** Example  Hohmann Transfer
Changing the way dark rooms are described to avoid the standard Inform phrasing.

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*** Example  Four Stars 1
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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* Example  Peeled
Two different approaches to adjusting what the player can interact with, compared.

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*** Example  Unblinking
Finding a best route through light-filled rooms only, leaving aside any that might be dark.

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**** 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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