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<HTML><HEAD><TITLE>Section 10: Places, scenery, directions and the map</TITLE></HEAD>
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<BODY BGCOLOR="#FFFFFF">
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<TR><TD Valign="top"><A HREF="contents.html">Contents</A><BR><A HREF="chapter4.html">Back</A><BR><A HREF="section11.html">Forward</A><TD bgcolor="#F5DEB3"><BLOCKQUOTE><H3>10. Places, scenery, directions and the map</H3></BLOCKQUOTE><TR><TD><TD>
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It was a long cylinder of parchment, which he unrolled and spread out
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on the floor, putting a stone on one end and holding the other.
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I saw a drawing on it, but it made no sense.
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<P>...John Christopher (<B>1922</B>--), <I>The White Mountains</I></BLOCKQUOTE>
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Back to 'Ruins': what lies at the foot of the stone steps? We'll now
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add four rooms, connected together:
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Square Chamber <--> Web
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with the Square Chamber lying underneath the original Forest location.
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For instance, here's the Square Chamber's definition:
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Object Square_Chamber "Square Chamber"
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with name "lintelled" "lintel" "lintels" "east" "south" "doorways",
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"A sunken, gloomy stone chamber, ten yards across. A shaft
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of sunlight cuts in from the steps above, giving the chamber
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a diffuse light, but in the shadows low lintelled doorways to
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east and south lead into the deeper darkness of the Temple.",
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u_to Forest, e_to Web, s_to Corridor,
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Like the Forest, this place has <TT>light</TT>, however dim. (If it didn't, the
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player would never see it, since it would be dark, and the player hasn't yet
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been given a lamp or torch of some kind.) Now although this is a room,
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and can't be referred to by the player in the way that a manipulable object
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can, it still can have a <TT>name</TT> property. These <TT>name</TT> words are those which
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Inform knows "you don't need to refer to'', and it's a convention of the
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genre that the designer should signpost off the game in this way. (Note
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that they'll only be looked at if what the player types is unrecognised,
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so the word "east'' is understood quite normally; but a reference to
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"east lintel'' will get the "don't need to refer to'' treatment.)
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This room is unfurnished, so:
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Object -> "carved inscriptions"
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with name "carved" "inscriptions" "carvings" "marks" "markings" "symbols"
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"moving" "scuttling" "crowd" "of",
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"Carved inscriptions crowd the walls, floor and ceiling.",
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description "Each time you look at the carvings closely, they seem
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to be still. But you have the uneasy feeling when you look
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away that they're scuttling, moving about. Their meaning
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This is part of the fittings, hence the <TT>static</TT> attribute, which means it
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can't be taken or moved. As we went out of our way to describe a shaft
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of sunlight, we'll include that as well:
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Object -> sunlight "shaft of sunlight"
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with name "shaft" "of" "sunlight" "sun" "light" "beam" "sunbeam" "ray"
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description "The shaft of sunlight glimmers motes of dust in the
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air, making it seem almost solid."
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(The <TT></TT> symbol in <TT>"sun^s"</TT> means an apostrophe, so the word is "sun's''.)
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Being <TT>scenery</TT> makes the object not only static but also not described
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by the game unless actually examined by the player. A true perfectionist
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might add a <TT>before</TT> rule:
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default: "It's only an insubstantial shaft of sunlight.";
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so that the player can look at or through the sunlight, but any other
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request involving them will be turned down. Note that a <TT>default</TT>
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rule, if given, means "any action except those already mentioned''.
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We can't actually get into the Square Chamber yet, though. Just because
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there is a map connection up from here to the Forest, it doesn't follow
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that there's a corresponding connection down. So we must add a <TT>d_to</TT>
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to the Forest, and while we're at it:
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u_to "The trees are spiny and you'd cut your hands to ribbons
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trying to climb them.",
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cant_go "The rainforest-jungle is dense, and you haven't hacked
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through it for days to abandon your discovery now. Really,
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you need a good few artifacts to take back to civilization
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before you can justify giving up the expedition.",
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The property <TT>cant_go</TT> contains what is printed when the player tries to go
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in a nonexistent direction, and replaces "You can't go that way''.
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As is often the case with properties, instead of giving an actual
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message you can instead give a routine to print one out, to vary what's
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printed with the circumstances. The Forest needs a <TT>cant_go</TT> because
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in real life one could go in every direction from there: what we're
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doing is explaining the game rules to the player: go underground, find some
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ancient treasure, then get out to win. The Forest's <TT>u_to</TT> property is
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a string, not a room; this means that attempts to go up result only in
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that string being printed.
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Rooms also have rules of their own. We might add the following <TT>before</TT>
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rule to the Square Chamber:
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if (noun==mushroom && second==sunlight)
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"You drop the mushroom on the floor, in the glare of
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the shaft of sunlight. It bubbles obscenely,
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distends and then bursts into a hundred tiny insects
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which run for the darkness in every direction. Only
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tiny crumbs of fungus remain.";
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The variables <TT>noun</TT> and <TT>second</TT> hold the first and second nouns
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supplied with an action. Rooms have <TT>before</TT> and <TT>after</TT> routines just as
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objects do, and they apply to anything which happens in the given room.
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This particular rule could easily enough have been part of the definition of
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the mushroom or the sunlight, and in general a room's rules are best used
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only for geographical fixtures.
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<P><TR><TD Valign="top"><IMG SRC="icons/ddbend.gif" ALT="/\/\"><TD bgcolor="#EEEEEE"><SMALL> Sometimes the room may be a different one after the action has
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taken place. The <TT>Go</TT> action, for instance, is offered to the <TT>before</TT>
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routine of the room which is being left, and the <TT>after</TT> routine of the
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room being arrived in. For example:
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[; Go: if (noun==d_obj)
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print "You feel on the verge of a great discovery...^";
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will print the message when its room is entered via the "down" direction.
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Note that since the message is printed with the <TT>print</TT> command,
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there is no "return true'' from this routine, so it returns false:
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and so the usual game rules resume after the printing of the message.
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Some objects are present in many rooms at once. The 'Ruins', for
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Object low_mist "low mist"
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with name "low" "swirling" "mist",
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initial "A low mist swirls about your feet.",
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description "The mist carries a rich aroma of broth.",
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found_in Square_Chamber Forest,
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[; Examine, Search: ;
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Smell: <<Examine self>>;
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default: "The mist is too insubstantial.";
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The <TT>found_in</TT> property gives a list of places in which the mist
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is found (so far just the Square Room and the Forest).
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<P><TR><TD Valign="top"><IMG SRC="icons/dbend.gif" ALT="/\"><TD bgcolor="#EEEEEE"><SMALL> If the rainforest contained many misty rooms, it would be tedious to
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give the full list and even worse to have to alter it as the mist drifted
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about in the course of the game. Fortunately <TT>found_in</TT> can contain a
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routine instead of a list. This can look at the current <TT>location</TT> and say
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whether or not the object should be put in it when the room is entered, e.g.,
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[; if (location has light) rtrue;
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<P><TR><TD Valign="top"><IMG SRC="icons/ddbend.gif" ALT="/\/\"><TD bgcolor="#EEEEEE"><SMALL> <TT>found_in</TT> is only consulted when the player's location changes,
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so if the mist has to dramatically lift or move then it needs to be moved
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or removed 'by hand'. A good way to lift the mist forever is to <TT>remove</TT>
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it, and then give it the <TT>absent</TT> attribute, which prevents it from
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manifesting itself whatever <TT>found_in</TT> says.
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Some pieces of scenery afflict the other four senses. The mist smells
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of broth, which means that if the player types "smell'' in a place
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where the mist is, then she should be told about the broth. For this,
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a <TT>react_before</TT> rule attached to the mist is ideal:
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[; Smell: if (noun==0) <<Smell low_mist>>;
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This is called a "react'' rule because the mist is reacting to the
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fact that a <TT>Smell</TT> action is taking place nearby. <TT>noun</TT> is compared
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with zero to see if the player has indeed just typed "smell'' (not,
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say, "smell crocus''). Thus, when the action <TT>Smell</TT> takes place
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near the mist, it is converted into <TT>Smell low_mist</TT>; whereas the
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action <TT>Smell crocus</TT> would be left alone.
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The five senses all have actions in Inform: <TT>Look</TT>, <TT>Listen</TT>,
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<TT>Smell</TT>, <TT>Taste</TT> and <TT>Touch</TT>. Of these, <TT>Look</TT> never has a noun
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attached (because <TT>Examine</TT> is provided for close-ups), <TT>Smell</TT> and
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<TT>Listen</TT> may or may not have while <TT>Taste</TT> and <TT>Touch</TT> always
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<P><TR><TD Valign="top"><IMG SRC="icons/exercise.gif" ALT="??"><TD bgcolor="#FBB9AC"><A NAME="ex5"><B>EXERCISE 5:</B><BR>(link to <A HREF="answers1/answer5.html">the answer</A>)<TR><TD><TD> (Cf. 'Spellbreaker'.) Make an orange cloud descend on the
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player, which can't be seen through or walked out
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Directions (such as "north") are objects called <TT>n_obj</TT>, <TT>s_obj</TT>
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and so on: in this case, <TT>in_obj</TT>. (They are not to be confused with the
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property names <TT>n_to</TT> and so on.) Moreover, you can change these
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directions: as far as Inform is concerned, a direction is any object in
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the special object <TT>compass</TT>.
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<P><TR><TD Valign="top"><IMG SRC="icons/dexercise.gif" ALT="??/\"><TD bgcolor="#FBB9AC"><A NAME="ex6"><B>EXERCISE 6:</B><BR>(link to <A HREF="answers1/answer6.html">the answer</A>)<TR><TD><TD> In the first millenium A.D., the Mayan peoples of the
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Yucat\'an Peninsula had 'world colours' white (<I> sac</I>), red (<I> chac</I>),
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yellow (<I> kan</I>) and black (<I> chikin</I>) for what we call the compass
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bearings north, east, south, west (for instance west is associated
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with 'sunset', hence black, the colour of night). Implement this.
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<P><TR><TD Valign="top"><IMG SRC="icons/dexercise.gif" ALT="??/\"><TD bgcolor="#FBB9AC"><A NAME="ex7"><B>EXERCISE 7:</B><BR>(link to <A HREF="answers1/answer7.html">the answer</A>)<TR><TD><TD> (Cf. 'Trinity'.) How can the entire game map
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be suddenly east-west reflected?
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<P><TR><TD Valign="top"><IMG SRC="icons/ddexercise.gif" ALT="??/\/\"><TD bgcolor="#FBB9AC"><A NAME="ex8"><B>EXERCISE 8:</B><BR>(link to <A HREF="answers1/answer8.html">the answer</A>)<TR><TD><TD> Even when the map is reflected, there may be many
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room descriptions referring to "east'' and "west'' by name. Reflect
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<P><TR><TD Valign="top"><IMG SRC="icons/dbend.gif" ALT="/\"><TD bgcolor="#EEEEEE"><SMALL> The ordinary Inform directions all have the <TT>number</TT>
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property defined (initially set to zero): this is to provide a
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set of scratch variables useful, for instance, when coding mazes.
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<P><TR><TD Valign="top"><IMG SRC="icons/ddbend.gif" ALT="/\/\"><TD bgcolor="#EEEEEE"><SMALL> If the constant <TT>WITHOUT_DIRECTIONS</TT> is defined before
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inclusion of the library files, then 10 of the default direction
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objects are not defined by the library. The designer is expected to
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define alternative ones (and put them in the <TT>compass</TT> object);
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otherwise the game will be rather static. (The "in" and "out"
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directions are still created, because they're needed for getting
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into and out of enterable
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<P><TR><TD Valign="top"><IMG SRC="icons/refs.gif" ALT="*"><TD bgcolor="#EEEEEE"><B>REFERENCES:</B><BR><SMALL> 'Advent' has a very tangled-up map in places (see the
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mazes) and a well-constructed exterior of forest and valley
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giving an impression of space with remarkably few rooms. The
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mist object uses <TT>found_in</TT> to the full, and see also the
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stream (a single object representing every watercourse in the game).
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Bedquilt and the Swiss Cheese room offer classic confused-exit
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For a simple movement rule using <TT>e_to</TT>, see the Office in
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The library extension "smartcantgo.h'' by David Wagner
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provides a system for automatically printing out "You can only go
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east and north.''-style messages.
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<BR> 'A Scenic View', by Richard Barnett, demonstrates
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a system for providing examinable scenery much more concisely
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(without defining so many objects).
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<HR><A HREF="contents.html">Contents</A> / <A HREF="chapter4.html">Back</A> / <A HREF="section11.html">Forward</A> <BR>
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<A HREF="chapter1.html">Chapter I</A> / <A HREF="chapter2.html">Chapter II</A> / <A HREF="chapter3.html">Chapter III</A> / <A HREF="chapter4.html">Chapter IV</A> / <A HREF="chapter5.html">Chapter V</A> / <A HREF="chapter6.html">Chapter VI</A> / <A HREF="chapterA.html">Appendix</A><HR><SMALL><I>Mechanically translated to HTML from third edition as revised 16 May 1997. Copyright © Graham Nelson 1993, 1994, 1995, 1996, 1997: all rights reserved.</I></SMALL></BODY></HTML>
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