Situations
In Undum, all interaction takes place in a situation. You
can think of it either as a 'Room' in traditional
interactive fiction (although it is less flexible than
that), or as a 'Page' in a Choose Your Own Adventure book
(though it is more flexible than that).
At any point, the character is in exactly one situation, and
that situation is responsible for everything that happens to
them. Situations are chunks of code that generate the output
you are reading here. For example, this text was generated
by the enter method of the 'situations' situation.
Let's move on again.
Saving and Loading
The only piece of the UI we haven't talked about is the
'Save' and 'Erase' buttons on the left panel. These are only
visible if your browser supports client-side data
storage. Clicking 'Save' stores your game, so you can pick
it up again later. There is currently no 'Load' button, the
game loads when the page loads. There is also no way to save
multiple games, and select which one you want to play. These
are both things I'd like to change in the future.
Potentially your game could generate huge amounts of
text. And that would be difficult to store client side
(there are unpredictable limits), especially when we move
towards having multiple save files. So instead Undum saves
your character as the list of links you clicked. Loading a
save-file consists of playing through your game again,
quickly. This is a beneficial approach for debugging too. It
means when you're polishing and correcting typos, you can
save and load the game and scroll through the transcript to
see your corrections. If we saved the text, your save file
would have the error in it and you'd have to manually replay
the game to see the correction.
Let's return to the topic list.
Locations
Choose a destination.
When you're writing an Undum game, you often need certain
options to be available only when certain conditions hold. You
might have an option to remove a secret panel in a haunted
house, but that should only be visible if the character knows
where it is. If options are available in lots of situations, it
can be very difficult to keep track of what options are
allowed, and to produce just the right list of choices.
To help with this, Undum can generate a list of situation
links for you. It does this in three steps. Firstly, each
situation can be given one or more tags, this allows you to
easily ask for links to all situations with the 'in-hallway'
tag, for example. Secondly, situations can have
a canView method, which gets to decide whether that
situation should appear. That method can look at the
current state of the character to decide whether to appear
or not. Thirdly, SimpleSituations have a choices
option. If it is set to one or more tags, it handles the building
of the choice list.
You've seen this already in the topic list. The topic list
is generated automatically. All of the situations in the topic
list are always available, however.
So here is an example of
automatic options that may change:
You can return to the
Topic List or choose another option from
this example:
