Chapter 3: Place
3.1. Room Descriptions

The printing of a room description is a more delicate business than it might initially seem to be: Inform has to consider all the objects that the player might have brought into the room or dropped there, and all the objects on visible supporters, and decide how to group and list them.

All of this behavior is handled by the looking command, so we find the relevant rules in the carry out looking rulebook. To go through the elements step by step:

Looking begins by printing the name and description of the room we're in. We can introduce variations into room names and descriptions by changing their printed name and description properties, as in

change the printed name of the Church to "Lightning-Struck Ruin";
change the description of the Church to "The beams overhead have been burnt away and the pews are charred. Only the stone walls remain.";

If we need more drastic effects, we can turn off or change either of these features by altering the rules in the carry out looking rulebook. For instance, to remove the name of the location entirely from room descriptions, we would write

The room description heading rule is not listed in the carry out looking rules.

(A word of warning: there is one other context in which the game prints a room name — when restoring a save or undoing a move. To omit the room title here too, add

Rule for printing the name of a room: do nothing.)

Ant-Sensitive Sunglasses demonstrates how to use activities to make more flexible room description text.

Next, the game determines what items are visible to the player and need to be described. These never include the player himself, or scenery, but other things in the environment will be made "marked for listing". This is also the stage at which Inform chooses the order in which items will be listed.

We are allowed to meddle by changing the priorities of objects, in case we want some things to be described to the player first or last in the room description; Priority Lab goes into detail about how. We can also force things to be left out entirely: Low Light handles the case of an object that can only be seen when an extra lamp is switched on, even though the room is not otherwise considered dark. Copper River implements the idea of "interesting" and "dull" objects: the game determines which items are currently important to the puzzles or narrative and mentions those in the room description, while suppressing everything else.

Then Inform carries out the writing a paragraph about... activity with anything that provides one; anything it prints the name of, it tags "mentioned". Thus

Rule for writing a paragraph about Mr Wickham:
    say "Mr Wickham looks speculatively at [list of women in the location]."

will count Wickham and everyone he looks at as all having been mentioned, and will not refer to them again through the rest of the room description. More complicated uses of writing a paragraph abound. A developed system for handling supporters that don't list contents appears in The Eye of the Idol.

Inform then prints the initial appearances of objects that are marked for listing but not already mentioned; and then it performs the listing nondescript items activity, collating the remaining objects into a paragraph like

You can see a dog, a hen, ...

We can pre-empt items from appearing in this paragraph or change their listing by intervening with a Before listing nondescript items... rule, as in

Before listing nondescript items when the player needs the watch:
    if the watch is marked for listing:
        say "The watch catches your eye.";
        change the watch to not marked for listing.

If we wanted the watch always to be listed this way, it would be better to give it an initial appearance, but for conditional cases, the listing nondescript items activity is a good place to intervene. For instance, Rip uses this activity to incorporate changeable or portable items into the main description text for a room when (and only when) that is appropriate.

The listing nondescript items activity also allows us to replace the "You can see..." tag with something else more fitting, if for instance we are in a dimly lit room.

When the game compiles the list of nondescript items, it adds tags such as "(open)" or "(empty)" or "(on which is a fish tank)" to the names of containers and supporters. We can suppress or change the "(empty)" tag with the printing room description details of activity, as in

Rule for printing room description details: stop.

And we can suppress the "(open)" and "(on which is...)" sorts of tags with the "omit the contents in listing" phrase, as in

Rule for printing the name of the bottle while not inserting or removing:
    if the bottle contains sand, say "bottle of sand";
    otherwise say "empty bottle";
    omit contents in listing.

Finally, the looking command lists visible non-scenery items that sit on scenery supporters, as in

On the table is a folded newspaper.

These paragraphs can be manipulated with the printing the locale paragraphs description activity.

Another common thing we may want to do is change the description of a room depending on whether we've been there before (as in Slightly Wrong) or on how often we've visited (as in Infiltration). Night Sky, meanwhile, changes the description of a room when we've examined another object, so that the player's awareness of his environment is affected by other things the character knows.

* See Looking for ways to change the default length of room descriptions


321
* Example  Ant-Sensitive Sunglasses
What are activities good for? Controlling output when we want the same action to be able to produce very flexible text depending on the state of the world -- in this case, making highly variable room description and object description text.

WI
344
* Example  Priority Lab
A debugging rule useful for checking the priorities of objects about to be listed.

WI
345
* Example  Low Light
An object that is only visible and manipulable when a bright light fixture is on.

WI
342
** Example  The Eye of the Idol
A systematic way to allow objects in certain places to be described in the room description body text rather than in paragraphs following the room description, and to control whether supporters list their contents or not.

WI
341
* Example  Rip Van Winkle
A simple way to allow objects in certain places to be described in the room description body text rather than in paragraphs following the room description.

WI
348
*** Example  Copper River
Manipulating room descriptions so that only interesting items are mentioned, while objects that are present but not currently useful to the player are ignored.

WI
3
** Example  Slightly Wrong
A room whose description changes slightly after our first visit there.

WI
152
* Example  Infiltration
A room whose description changes depending on the number of times the player has visited.

WI

Suppose we have a location that makes the player uncomfortable, and we want its description to change slightly each time he goes there, to reflect his increasing unease. We also want the door to that room to show whether he is going there for the first time, or whether this is a repeat visit.

We start with an ordinary room:

"Infiltration"

The Wasteland is a room. "In its more distant reaches, the Wasteland has a kind of austere beauty, but here beside the Secure Zone it is the worst of all possible worlds. Barrels of toxins are stacked the regulation hundred and fifty feet out; more traditional garbage has simply been flung over the wall, and this category includes one or two corpses roughly and inadequately disguised by black plastic bags. The wall itself has become a canvas for outcasts and exiles, and is covered with obscene paintings, lewd remarks about the inhabitants of the Secure Zone, and a few maudlin epitaphs."

Now the door, which will change from saying "leads inside..." to "leads back inside..." when this becomes appropriate:

The portal is a door. It is inside from the Wasteland and outside from the Secure Zone. "[if the player is in the Wasteland]To the west, a[otherwise]A[end if] portal in the cinder-block and barbed wire wall leads[if the player is in the Wasteland and the Zone is visited] back[end if] [if the player is in the Wasteland]inside[otherwise]outside[end if]."

Here we haven't used any conditions that we didn't know about in previous sections: the portal line only reflects whether the Zone has been visited never or visited once. But the Secure Zone itself makes use of the number of times visited:

The Secure Zone has the description "[if the player is in the Zone for the second time]Re-entering the Zone has not made you any more comfortable inside. [end if]Despite your carefully-chosen outfit and the walk you have been practicing, you are sure those inside can tell you don't belong. Not that very many people are visible here[if the player is in the Zone for more than the second time] -- the place seems more desolate than ever[end if]."

Instead of going west in the Wasteland, try going inside. Instead of going east in the Secure Zone, try going outside.

And finally, to be sure that the player does see our fancy changing descriptions:

Use full-length room descriptions.

Test me with "look / open portal / w / look / e / look / w / e / w".

Notice that the description of the Secure Zone changes from visit to visit, but that looking repeatedly during a single visit changes nothing.

147
* Example  Night Sky
A room which changes its description depending on whether an object has been examined.

WI


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