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The Area Engine

• The Area Engine
  • Overview
  • File Format
    • Comments
    • The [general] section
    • The [map] section
    • The [exits] section
    • The [rooms] section
      • Rooms that are part of your area
      • Rooms that are outside your area or are hand coded
      • Understanding how room descriptions are allocated
      • What can go in a room description block
      • What can go into an external room identification block
    • The [specialobjects] section
      • What can go in a object description block
  • Advanced stuff
    • Available Modules
      • Exit Modules
    • Module example

Overview

Essentially it is a single "controller" that creates the rooms for you based on an area file. As a builder you write the area file and the area generates itself - no more creating rooms. At this time the area file only controls the rooms, their exits and descriptions, and the placement of externally created objects/monsters. It will soon provide the ability to define objects and monsters. After that, I'm open to suggestions.

File Format

The file is broken into a series of sections, each section having a heading and some content. Headings have the form [heading-name], and a section is all the content from its heading until the heading for the next section. Section headings have to be on a single line of their own.

The following shows you the outline of the file. A complete area file will probably include the sections shown here as well as having lots of content inside each section

[general]

[map]
# This section defines the layout of your area

[exits]
# This section defines special exits - doors/blocking/etc

[rooms]
# This section defines what your rooms look like
# and defines the external rooms (links to other areas)

[specialobjects]
# This section manages hand-coded objects like monsters
# and treasures

Comments

# I am a comment
[general]
I am not a comment.

[map]
# I am another comment
# that goes over multiple lines
I am not a comment

The [general] section

Supported constants at this time are:

Each constant goes on a line of its own and is assigned a value using the = operator.

For example:

[general]
# Define 'domain' to be 123
domain=123

#define 'startroom' to be 'hallway'
startroom=hallway

The [map] section

This section does not define the contents of rooms, nor the room descriptions, just the exits/links between rooms.

Each room is defined on a single line. The line has the format:

After the ":" are the exits for the room, separated with commas. Each exit is a direction, an "=" sign, and the room_key for the destination.

So - the following map is used to describe a 2 story house with several rooms:

[general]
# Make people start in the lounge
startroom=lounge

[map]
# This comment is just describing the layout below, 
#   the area creator ignores it completely
# The ground floor map looks like:

# kitchen   -  dining  
#    |      \     |
# hallway    lounge - outside
#    |
# hallway - bedroom
#    |
# hallway - bedroom
#    <

# The second story looks like

# bedroom - onsuite
#   |
# landing
#   >

# The "outside" room is not in this area, it's the room for entering this area

# Below here are the actual rooms with their exits
kitchen: e=dining,s=hallway1,se=lounge
dining: w=kitchen,s=lounge
lounge: nw=kitchen,n=dining,frontdoor=outside
hallway1: n=kitchen,s=hallway2
hallway2: n=hallway1,s=hallway3,e=bedroom1
hallway3: n=hallway2,e=bedroom2,u=landing
bedroom1: w=hallway1
bedroom2: w=hallway2
landing: d=hallway3,n=masterbedroom
masterbedroom: s=landing,e=onsuite
onsuite:w=masterbedroom

Note that there is no room with a room_key = "outside". This is because the room is specially coded - it is either a hand-coded room which you want to connect with, or it is a room managed by a different area engine.

The [exits] section

The [exits] section is sort of optional.

In this section you define the details of exits. Details include things like

• the actual direction of the exit (if you want it to be a different word to the actual exit name),
• a door in the exit.
• special blocks on the door, like the player having to have completed a quest, or be in a guild.

So, for example, in the map above there are exits described as "e", "w" and so on. By default this means the exits in the rooms will be exactly that: "e" and "w", not "east" and "west".

More interestingly the definition for room "lounge" has an exit called "frontdoor", which leads to the outside. It seems unlikely that we want the player to see that - rather we want them to see an "east" exit, and for it to be a wooden door.

The following shows the configuration for the "frontdoor" exit

[exits]
# define the frontdoor as a normal east exit.  In the
# future we might define this as an actual door which opens
# and closes.  See the 'door' exit module for help on how to do this.
exit: frontdoor
direction: east

The [rooms] section

The [rooms] section defines the appearance of rooms - the description, items, light levels, etc. This section DOES NOT define the exits/connections between rooms - that is done in the [map] section.

The [rooms] section is broken up into a series of individual room descriptions. Each room description can apply to one or more of the rooms which are defined in the [map] section. This is deliberately done to allow you to use a generic room description for multiple rooms in your area.

The [rooms] section also identifies rooms that are outside your area, or have been specially hand-coded by a wizard. You need to identify these rooms and tell the Area Engine how to find them so that your rooms can link to the rest of the mud.

Rooms that are part of your area

[rooms]
room:
# this is the first room description
# and so is this

room:
# this is the description for the next room

Rooms that are outside your area or are hand coded

Each external room description starts with a line that begins with external: . All subsequent lines until the next room: or external are considered to be part of identification of the external room.

[rooms]
room:
# this is the first room description
# and so is this

external: outside
# this is the 'outside' room and is a room that is probably a room in an adjoining area.
# The Area Engine will expect to be told where to find the file/map for the external room.

room:
# this is the description for the next room

Understanding how room descriptions are allocated

Putting a room in the [rooms] section doesn't cause the room to be created, the actual rooms that get created are controlled by the [map] section. The Area Engine examines the [map] section to work out which rooms should exist.

When a room is to be created the Area Engine will:

1. check to see if there is an external definition in the [rooms] and if so then use that external room.
2. assuming no external room can be found then it will get the entire set of room descriptions from the [rooms],
3. determine the subset of the descriptions that are possibilities for this room, and
4. randomly choose one of these.

The important thing to understand is how the Area Engine performs the third step - the process of working out which room descriptions can apply to a given room. It is possible for you to create an area with a single room description which can apply to all rooms, it is also possible to create an area in which each room has only a single applicable room description (in which case you have as many room descriptions as you do rooms in your [map]), and anywhere in-between.

The Area Engine works out which room descriptions can be applied to a room using the room: line.

The room: line has the form:

room: room_key_pattern,room_key_pattern,room_key_pattern,etc

The room_key_pattern is a string which indicates which of the room_keys from the [map] the room description can apply to. The pattern can include an "*" to match any characters. As shown it is possible to specify multiple patterns by separating them with commas.

A special circumstance applies if you specify NO room_key_patterns. Rooms descriptions with no room_key_patterns may be used for rooms which match no other room descriptions.

For example, presuming we have the map of the house from above we can use the following descriptions:

[rooms]
# This description applies to only the kitchen
room: kitchen
short: The kitchen
long: This is the kitchen, it is full of cooking stuff.

# This description can apply to any bedroom.
# Note that there are other descriptions below which have the 
# room_key_patterns that match the bedrooms, and thus the
# Area Engine will randomly choose one of these when assigning
# a description to each bedroom
room: *bedroom*
short: A bedroom
long: A room with a messy bed in it, someone has slept here recently.

# This description can apply to any bedroom, but is specified
# using commas instead of a * wildcard.
room: bedroom1, bedroom2, masterbedroom
short: A bedroom
long: A room with a very neat and tidy bed in it.

# This description will apply to any room that does not match
# any of the other descriptions (IE all non-bedrooms and non-kitchens)
room:
short: A room
long: This room is completely bare.

# This description can also apply to any room that does not
# match the other definitions with room_key_patterns.  
# Thus the Area Engine will randomly choose either this description 
# or the one immediately above when describing all non-bedroom
# and non-kitchen rooms.
room:
short: A room
long: This room is tastefully furnished.

# This tells the Area Engine where to find the 'outside' room.
# It tells it that it is the 'street1' room in the 'town' domain.
external: outside
domain: DOM_TOWN
file: street1

What can go in a room description block

• short (brief description)
• long (verbose description)
• light (0 for dark, 1 for daylight)
• inside (0 for outside, 1 for inside)
• chat (a message that displays occassionally in the room). Can have many of these
• item (an item you can look at). Can have many of these.

What can go into an external room identification block

Examples include rooms that have been hand-coded by a wizard and rooms within other areas controlled by the area engine.

When linking to a room which has been hand coded by a wizard (or builder) you must specify:

• domain (optional, defaults to the domain for this area)
• file

When linking to a room which is part of another area-engine controlled area you must specify:

• domain - the name of the domain (optional, defaults to the domain for this area)
• area - the name of the area
• name - the name of the room (from the Map section. Optional, defaults to the default start room)

The [specialobjects] section

The [specialobjects] section is used to manage the placement of objects that are not defined within the area file; like hand-coded, or specially-coded monsters and treasures, perhaps created with the Blob.

The [specialobjects] section is is broken up into a series of individual objectdefinitions. Each description starts with a line that begins with object:

All subsequent lines until the next object: are considered to be part of the same object definition.

[specialobjects]
object: rabbit
# this is the definition for the 'rabbit' monster
# and so is this

object: table
# this is the definition for the 'table' treasure

Each object: line has the format:

object: object_key

The object_key is a unique keyword used to identify the object in other parts of the area file. You can use any keyword you like.

What can go in a object description block

keyword: value

Possible keywords, and their meanings are:

Advanced stuff

For example you might want exits to only be traversable if a certain monster is dead, or you might want a weapon to have a certain special attack, or ability when wielded.

This advanced functionality is provided through the use of extension modules .

Extension modules are things that you can use on almost anything facet in the Area Engine to make it behave in new and exciting ways.

Possible "targets" for extension modules are:

• Exits: Modules might do things like only allow you through if a monster is dead, or give special messages when the player passes through.
• Rooms: Modules can do anything at all to the room, such as making it slowly leach the life from all living things inside it, or they might make it change its description or exits.
• Monsters: Modules can alter the behaviour and everything else for the monster. Such as providing special attacks, or making them pick up items they find.

Modules are applied to a target using a common syntax. Within the target you write

   module: MODULE_NAME {
      KEY: VALUE
      KEY: VALUE
   }

or more simply:

   MODULE_NAME {
      KEY: VALUE
      KEY: VALUE
   }

The specified MODULE_NAME is the most important bit - it determines which module you are using, and thus what advanced effect you are applying. The next most important things is the pair of braces {}. The opening brace MUST appear on the end of the line containing the MODULE_NAME, and the closing brace MUST appear on a line of its own.

The KEY/VALUE pairs are used to configure the module. For example in the "exit" module called "guild_block", there is a keys which indicate which guild you have to be in to be able to use the exit, and in the "exit" module called "door" there is a key to indicate whether the door is lockable.

Available Modules

Exit Modules

Module example

[map]
# Just two rooms, and we give the exit from room1 to 2 a special name.
room1: blockedExit=room2
room2: west=room1

[exits]
# configure the exit called 'blockedExit'
exit: blockedExit
# make it go east
direction: east
# use 'door' module to add a gate
door {
   id: mydoor
   type: steel_gate
}
# use 'guild_block' module to stop non-thieves.  Note the use of the optional 'module:' prefix
module: guild_block {
   guild: ThiefGuildId
   message: You have to be a thief to go east!
}