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<TR><TD Valign="top"><A HREF="contents.html">Contents</A> <A HREF="section18.html">Back</A> <A HREF="section20.html">Forward</A><TD bgcolor="#F5DEB3"><BLOCKQUOTE><H3>19. Starting, moving, changing and killing the player</H3></BLOCKQUOTE><TR><TD><TD>

There are only three events in a man's life; birth, life and death;

he is not conscious of being born, he dies in pain and he forgets

to live.

...Jean de la Bruyére (1645--1696)</BLOCKQUOTE>

Life's but a walking shadow, a poor player

That struts and frets his hour upon the stage

And then is heard no more; it is a tale

Told by an idiot, full of sound and fury,

Signifying nothing.

...William Shakespeare (1564--1616), Macbeth V. v</BLOCKQUOTE>

The only compulsory task for a game's <TT>Initialise</TT> routine is to

set the <TT>location</TT> variable to the place where the player should begin.

This is usually a room (and is permitted to be one that's in darkness)

but could instead be an object inside a room, such as a chair or a bed.

If you would like to give the player some items to begin with, <TT>Initialise</TT>

should also <TT>move</TT> them to <TT>player</TT>.

Games with a long opening sequence might want to start by offering the player

a chance to restore a saved game at once. They can do so by writing the

following in their <TT>Initialise</TT> routines:

<PRE>

print "Would you like to restore a game? >";

if (YesOrNo()) <Restore>;

</PRE>

(If you want to make the status line invisible during an opening sequence, see

<A HREF="section33.html">Section 33</A>.) <TT>Initialise</TT> normally returns 0 or 1 (it doesn't matter which), but

if it returns 2 then no game banner will be printed at once. (This is for

games which, like 'Sorcerer', delay their banners until after the prologue.)

'Ruins', however, opens in classical fashion:

<PRE>

[ Initialise;

TitlePage();

location = Forest;

move food_ration to player;

move sodium_lamp to player;

move dictionary to player;

thedark.description = "The darkness of ages presses in on you, and you

feel claustrophobic.";

"^^^^^Days of searching, days of thirsty hacking through the briars of

the forest, but at last your patience was rewarded. A discovery!^";

];

</PRE>

(The <TT>TitlePage</TT> routine will be an exercise in <A HREF="section33.html">Section 33</A>: 'Ruins' is really

too small a game to warrant one, but never mind.)

The <TT>location</TT> variable needs some explanation. It holds either the current

room, if there's light to see by, or the special value <TT>thedark</TT> (the

"Darkness'' object) if there isn't. In the latter case (but only in the

latter case) the actual current room is held in the variable <TT>real_location</TT>,

should you need to know it. Neither of these is necessarily the same as

the parent of the <TT>player</TT> object. For instance, if the player sits in a

jeep parked in a dark garage, then <TT>location</TT> is <TT>thedark</TT>, <TT>real_location</TT>

is <TT>Garage</TT> and <TT>parent(player)</TT> is <TT>jeep</TT>.

Because of this, one shouldn't simply <TT>move</TT> the player object by hand.

Instead, to move the player about (for teleportation of some kind),

use the routine <TT>PlayerTo(place);</TT> (which automatically takes care of

printing the new room's description if there's enough light there to see

by).

<TR><TD Valign="top"><IMG SRC="icons/dbend.gif" ALT="/\"><TD bgcolor="#EEEEEE"> <TT>PlayerTo</TT> can also be used to move the player to a <TT>place</TT> inside

a room (e.g., a cage, or a traction engine).

<TR><TD Valign="top"><IMG SRC="icons/dbend.gif" ALT="/\"><TD bgcolor="#EEEEEE"> Calling <TT>PlayerTo(place, 1);</TT> moves the player but prints

nothing (in particular, prints no room description).

<TR><TD Valign="top"><IMG SRC="icons/dbend.gif" ALT="/\"><TD bgcolor="#EEEEEE"> Calling <TT>PlayerTo(place, 2);</TT> will <TT>Look</TT> as if the player had

arrived in the room by walking in as usual, so only a short description

appears if the room is one that has been seen before.

<TR><TD Valign="top"><IMG SRC="icons/dbend.gif" ALT="/\"><TD bgcolor="#EEEEEE"> In a process called 'scoring arrival', a room which the player has entered

for the first time is given the <TT>visited</TT> attribute. If it was listed

as <TT>scored</TT>, points are awarded. (See <A HREF="section14.html">Section 14</A>.)

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<TR><TD Valign="top"><IMG SRC="icons/ddbend.gif" ALT="/\/\"><TD bgcolor="#EEEEEE"> When a <TT>Look</TT> action takes place, or a call to <TT>PlayerTo(place,1)</TT>,

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the library 'notes arrival' as well as 'scores arrival'.

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'Noting arrival' consists of checking to see if the room has changed

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since last time (darkness counting as a different room for this purpose).

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If so, the following happens:

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1. -- If the new location has an <TT>initial</TT> property, this is printed

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if it's a string, or run if it's a routine.

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2. -- The entry point <TT>NewRoom</TT> is called (if it exists).

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3. -- Any 'floating objects', such as drifting mist, which are <TT>found_in</TT>

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many places at once, are moved into the room.

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The player's whole persona can easily be changed, because the player object

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can itself have an <TT>orders</TT> routine, just as the object for any non-player

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character can. To replace the <TT>orders</TT> routine for the standard <TT>player</TT>

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object, set

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<PRE>

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player.orders = MyNewRule;

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</PRE>

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where <TT>MyNewRule</TT> is a new <TT>orders</TT> rule. Note that this is applied to

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every action or order issued by the player. The variable <TT>actor</TT> holds the

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person being told to do something, which may well be the player himself,

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and the variables <TT>action</TT>, <TT>noun</TT> and <TT>second</TT> are set up as usual.

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For instance, if a cannon goes off right next to the player,

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a period of partial deafness might ensue:

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<PRE>

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[ MyNewRule;

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if (actor~=player) rfalse;

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Listen: "Your hearing is still weak from all that cannon-fire.";

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];

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</PRE>

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The <TT>if</TT> statement needs to be there to prevent commands like

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"helena, listen'' from being ruled out -- after all, the player

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can still speak.

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<TR><TD Valign="top"><IMG SRC="icons/dexercise.gif" ALT="??/\"><TD bgcolor="#FBB9AC"><A NAME="ex42">EXERCISE 42: (link to <A HREF="answers1/answer42.html">the answer</A>)<TR><TD><TD> Why not achieve the same effect by giving the player

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a <TT>react_before</TT> rule instead?

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<TR><TD Valign="top"><IMG SRC="icons/exercise.gif" ALT="??"><TD bgcolor="#FBB9AC"><A NAME="ex43">EXERCISE 43: (link to <A HREF="answers1/answer43.html">the answer</A>)<TR><TD><TD> (Cf. 'Curses'.) Write an <TT>orders</TT> routine for the player

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so that wearing the gas mask will prevent him from

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talking.

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<TR><TD Valign="top"><IMG SRC="icons/dbend.gif" ALT="/\"><TD bgcolor="#EEEEEE"> In fact a much more powerful trick is available: the <TT>player</TT> can

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actually become a different character in the game, allowing the real player

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at the keyboard to act through someone else.

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Calling <TT>ChangePlayer(obj)</TT> will transform the player to <TT>obj</TT>. There's

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no need for <TT>obj</TT> to have names like "me'' or "myself''; the

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parser understands these words automatically to refer to the

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currently-inhabited <TT>player</TT> object. However, it must provide a <TT>number</TT>

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property (which the library will use for workspace). The maximum number

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of items the player can carry as that object will be its <TT>capacity</TT>. Finally,

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since <TT>ChangePlayer</TT> prints nothing, you may want to conclude with a <TT><<Look>>;</TT>

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<TR><TD><TD bgcolor="#EEEEEE"> <TT>ChangePlayer</TT> has many possible applications. The player

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who tampers with Dr Frankenstein's brain transference machine may

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suddenly become the Monster strapped to the table. A player who drinks

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too much wine could become a 'drunk player object' to whom many different

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rules apply. The "snavig'' spell of 'Spellbreaker', which transforms

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the player to an animal like the one cast upon, could be implemented thus.

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More ambitiously, a game could have a stock of half a dozen main characters,

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and the focus of play can switch between them. A player might have a team

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of four adventurers to explore a dungeon, and be able to switch the one

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being controlled by typing the name. In this case, an <TT>AfterLife</TT> routine

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-- see below -- may be needed to switch the focus back to a still-living

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member of the team after one has met a sticky end.

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<TR><TD Valign="top"><IMG SRC="icons/dbend.gif" ALT="/\"><TD bgcolor="#EEEEEE"> Calling <TT>ChangePlayer(object,1);</TT> will do the same but make the

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game print "(as Whoever)'' during room descriptions.

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<TR><TD Valign="top"><IMG SRC="icons/ddbend.gif" ALT="/\/\"><TD bgcolor="#EEEEEE"> When the person to be changed into has an <TT>orders</TT> routine,

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things start to get complicated. It may be useful to arrange such a

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routine as follows:

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<PRE>

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orders

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[; if (player==self)

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{ ! I am the player object...

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if (actor==self)

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{ ! ...giving myself an order, i.e., trying an action.

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}

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else

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{ ! ...giving someone else, the "actor", an order.

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}

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}

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else

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{ ! The player is the "actor" and is giving me an order.

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}

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</PRE>

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<TR><TD Valign="top"><IMG SRC="icons/dexercise.gif" ALT="??/\"><TD bgcolor="#FBB9AC"><A NAME="ex44">EXERCISE 44: (link to <A HREF="answers1/answer44.html">the answer</A>)<TR><TD><TD> In Central American legend, a sorceror can transform himself

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into a nagual, a familiar such as a spider-monkey; indeed, each

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individual has an animal self or wayhel, living in a volcanic land

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over which the king, as a jaguar, rules. Turn the player into his

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wayhel.

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<TR><TD Valign="top"><IMG SRC="icons/ddexercise.gif" ALT="??/\/\"><TD bgcolor="#FBB9AC"><A NAME="ex45">EXERCISE 45: (link to <A HREF="answers1/answer45.html">the answer</A>)<TR><TD><TD> Write an <TT>orders</TT> routine for a Giant with a conscience,

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who will refuse to attack a mouse, but so that a player who becomes

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the Giant can be as cruel as he likes.

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The player is still alive for as long as the variable <TT>deadflag</TT> is zero.

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When set to 1, the player dies; when set to 2, the player wins; and all higher

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values are taken as more exotic forms of death. Now Inform does not know

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what to call these exotica: so if they should arise, it calls the

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<TT>DeathMessage</TT> routine, which is expected to look at <TT>deadflag</TT> and

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can then print something like "You have changed''.

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Many games allow reincarnation (or, as David M. Baggett points out, in

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fact resurrection).

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You too can allow this, by providing an <TT>AfterLife</TT>.

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This routine gets the chance to do as it pleases before any "You are

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dead'' type message appears, including resetting <TT>deadflag</TT> back to 0 --

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which causes the game to proceed in the normal way, rather than end.

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<TT>AfterLife</TT> routines can be tricky to write, though, because the game

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has to be set to a state which convincingly reflects what has happened.

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<TR><TD Valign="top"><IMG SRC="icons/refs.gif" ALT="*"><TD bgcolor="#EEEEEE">REFERENCES:

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The magic words "xyzzy'' and "plugh'' in 'Advent' make use of

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<TT>PlayerTo</TT>.

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'Advent' has an amusing <TT>AfterLife</TT> routine: for instance,

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try collapsing the bridge by leading the bear across, then returning

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to the scene after resurrection. 'Balances' has one which only

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slightly penalises death.

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</TABLE>

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<HR><A HREF="contents.html">Contents</A> / <A HREF="section18.html">Back</A> / <A HREF="section20.html">Forward</A>

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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>Mechanically translated to HTML from third edition as revised 16 May 1997. Copyright © Graham Nelson 1993, 1994, 1995, 1996, 1997: all rights reserved.</BODY></HTML>

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