Oweng4000 wrote:
Quote:
I actually don't think it would be that hard. You'd just need a text representation of a potentially-cyclic event graph tagged with vertices as events and edges as commands to move between events. The program to interpret that might be somewhat short, I think.
So what your saying is, I would need two integer variables, for example A and B, which would represent the characters position? That sounds like it might work.
Noooo... That's not it at all. The concept of IF is that you have "Rooms" which hold everything in the universe of the game. They have descriptions, and names, and could have attributes.
AGT Sample Game wrote:
ROOM 2
Dark Pit
WEST 3 (* Storage Room *)
END_ROOM
ROOM_DESCR 2 (* Dark Pit *)
You are in a deep pit. Climbing back up is simply impossible: the side of the
pit is far too steep and is too slippery to grip. Through a shattered wooden
door, you can faintly make out an exit to the west.
END_ROOM_DESCR
(Note that this is AGT specific code, and that other languages may differ in syntax and design)
The bit called "Room_Description" is displayed when the player enters the room, and when he/she types "look". The rooms are connected to other rooms in various directions. For example: in this game, room 2 is connected to room 3 in the west direction. Trying to move any other way might generate a "You can't go that way", or a "You try to climb the walls, but they're just too slippery." The rooms don't have to be connected in any particular way. (A popular puzzle in many games is to stick the player into a maze of interconnected rooms)
Another thing that comes into play are nouns. If there weren't any nouns, you wouldn't be able to do anything but walk around. Nouns can have many properties, including being a weapon, lockable, closeable, (im)moveable, a light source, a key, and even readable. They also may have properties such as size, and weight, and where they are initially located.
AGT Sample Game wrote:
NOUN 201
Crowbar
Iron
There is an iron crowbar here.
WEIGHT 10
SIZE 20
LOCATION 2 (* Dark Pit *)
(everything else is default)
NOUN_SYNONYMS rod bar
END_NOUN
NOUN_DESCR 201 (* Iron Crowbar *)
The iron crowbar is about three feet long and weighs about eight pounds.
It might be useful as a weapon or as a tool, depending on the circumstances.
END_NOUN_DESCR
From this excerpt, we can glean that its name is the crowbar, it is iron, and it can also be called a rod or a bar. It starts in room 2 (Which is a dark pit, as referenced by the comment). The line of text below the adjective "Iron" is what is displayed when it is lying on the floor in a room. The long "Noun_Description" is what is displayed when it is examined.
AGT Sample Game wrote:
NOUN 202
Crate
Wooden
There is a large wooden crate here.
LOCATION 3 (* Storage Room *)
CLOSABLE
CLOSED
LOCKABLE
LOCKED
READABLE
KEY 201 (* iron crowbar *)
UNMOVABLE
NOUN_SYNONYMS lettering side writing box lid nail nails
END_NOUN
NOUN_DESCR 202 (* Wooden Crate *)
The crate is about eight feet long by six feet wide by six feet high. It is
extremely heavy and quite solid. There is lettering on the side. It has a
lid that is nailed to the top of the crate.
END_NOUN_DESCR
TEXT 202 (* Wooden Crate *)
The side of the crate says, "U.S. Emergency Radiation Supplies. Do Not Open."
END_TEXT
This one is a bit longer than the previous noun. It's closable, and lockable, and happens to be both. It's readable, so there's a "TEXT" for it, which will be displayed when it is read (i.e. "read crate"). The only way to open/unlock it is with the crowbar (i.e. "open crate with crowbar"). Nouns can also be in other nouns, so a radiation treatment kit could be in the box by setting its location to 202, the # of the crate.
Another thing in the game are NPCs. They can be hostile, or friendly, and may need to be killed or transported to a place in order to win. They may also block movement.
AGT Sample Game wrote:
CREATURE 301
Wolf
Grey
There is a grey wolf here, snarling and growling at you.
LOCATION 3 (* Storage Room *)
WEAPON 201 (* crowbar *)
HOSTILE
THRESHHOLD 3 (* can attack it 3 times *)
TIME_THRESH 5 (* can be in room for 5 turns *)
END_CREATURE
CREATURE_DESCR 301 (* Grey Wolf *)
The wolf is grey, with a few white spots on its belly. It is also quite large,
almost as tall as you are. Its claws look sharp. The wolf does not look
friendly; it growls and snarls, plainly upset that you have disturbed it.
END_CREATURE_DESCR
The wolf here is guarding the crate. Most of the rest should be self-explanatory, with the comments. A player cannot exit the room in which a hostile creature is in until he/she has killed it. Creatures can also follow the player around, and lend their witticisms. One more thing to note is that all objects (Nouns/Creatures) can have a point value attached to them that can be gained by acquiring them/killing them/meeting them.
At this point, you may be thinking that IF is pretty dull, after all, all you can do is walk around acquiring things, and fighting NPCs. Not so: IF has one more trick op its sleeve,well maybe a couple... Specials. Specials perform an action, such as moving a player, or altering his/her's status.
'Crusade' wrote:
ROOM 43
Thick woods
NORTH 43
SOUTH 4
EAST 43
WEST 2
ROOM_SYNONYMS CHANGE_LOCATIONS CLIMB GO
KEY 201 (* will cause 'CLIMB or GO TREE' to go to location 3 -- top of tree *)
SPECIAL 3
END_ROOM
...
NOUN 201
trees
large
There are large trees all around you.
LOCATION 43
UNMOVABLE
PLURAL
NOUN_SYNONYMS TREE
END_NOUN
...
ROOM 3
Tree top
DOWN 43
END_ROOM
...
SPECIAL 3
You struggle up branch by branch till you reach the tallest part of the tree.
END_SPECIAL
Let's break this up line by line: On the seventh line, the "ROOM_SYNONYMS" bit is just a list of synonyms. The "CHANGE _ROOMS" bit is a special word that makes the player change rooms when the given key is specified. The "Go" and "Climb" bits are just verbs that can be used. On the next line, There's a KEY. This is the noun that must be specified for the special to work. The SPECIAL bit just specifies what room to move to. When the player types "climb trees" he is moved to room 3, and special 3 is played.
I hope you have enjoyed this mini-tutorial on IF/AGT. Remember, there are may different programming languages out there with a variety of skill levels and expertise. From those like AGT, which you need little to no programming experience to use, to those like the Z-Machine format, which has the programmer create their own parser, the games you make with them are always fun.
A cyclic tagged graph is the perfect way to store and organize it. 
Did you as someone who actually knows that "vertex" and "node" are synonymous understand the gist of what I was saying? Or did I come off as a total wacko?