Magic and effects

Now we're getting to the fun stuff!

Casting spells

All spells can be divided into two categories: Instant and Persistent. Instant spells are simple, they are just like actions. A fireball spell is instant, for example. You simply create a FireballSpell and queue it off. When the spell is executed it does all the checks and mumbo jumbo and all that, and then fires off a fireball (no pun intended). Subtracts HP (or whatever) from the target. Then that's it - the spell is gone.

Persistent spells are a bit more complex. Take for instance a WerewolfSpell. The poor target will turn into a werewolf every evening for a week. Any spell that sticks around even after it has been cast is considered to be persistent. A persistent spell is added to the action queue as usual, but when executed it creates a new object - an Effect.

Effects

An effect is a subclass of Physical and is therefore part of the container hierarchy. That means it has a physical location in the world, even though it may be invisible. So when the WerewolfSpell has been cast on Joe, a WerewolfEffect will be created and added as a child to Joe (which means it will receive all events that Joe receives). The WerewolfEffect will sit there silently, watching the clock until evening comes along. Then it will unplug Joe's normal soul and plug in a WerewolfSoul instead, and perhaps change some physical attributes of Joe as well. The player controlling Joe will be very surprised as he notices his character running around snarling and eating live horses...

In the morning the WerewolfEffect will restore Joe's original attributes and give him back his normal soul. But it will still be there, waiting for next evening... he he he. Joe better go find an exorcist or something like that...

Another example could be an AntiOrcEffect that prevents orcs from entering a room. This Effect becomes a child of the Area itself, or perhaps a Place (if it has a limited radius). It will watch what is happening and if an orc comes in or too near it will turned it into a parrot...

Non-magical effects

Not all effects are magical. Activities often result in effects being generated for the duration of the activity. Like if someone starts singing a patriotic song a RaiseBattleMoraleEffect might be created for the duration of the song, affecting all creatures of the same nation within x squares.

So what's the difference between Effects and Activities?

A Physical can only be involved in one Activity, but can have many Effects.
A Physical always knows what Activity it is involved in - but Effects can be invisible.
Activities do not have a geographic location (since they aren't subclasses of Physical). Effects move around with their host.

Other than that, they are quite similar.

Special cases - affecting multiple targets

What about an effect that involves more than one target? Like a TwinCurseEffect which is cast on two targets and will damage the two targets whenever they move further than 3 squars from each other. Let's say it's cast on Joe and Fred. Where does the TwinCurseEffect reside - in Joe or Fred?

Well in this case there will probably be two instances of TwinCurseEffect, one for Joe and one for Fred. The TwinCurseEffect will also have references to each other, to keep track of their locations. Another way is to make just one TwinCurseEffect and put it in Joe, and make this TwinCurseEffect keep track of Fred explicitely. The difference here is that even the best exorcist in the world couldn't help Fred get rid of the curse - because he doesn't "have it" (in fact there isn't even a pointer from Fred to the curse), Joe does.

Of course that could be cool, in cases. Fred is affected by an "indirect" effect, an effect which resides somewhere else but is affecting him all the same... *shiver*

Henrik Kniberg

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