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94 lines
No EOL
3.6 KiB
Markdown
94 lines
No EOL
3.6 KiB
Markdown
# NPCs reacting to your presence
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> north
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------------------------------------
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Meadow
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You are standing in a green meadow.
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A bandit is here.
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------------------------------------
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Bandit gives you a menacing look!
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This tutorial shows the implementation of an NPC object that responds to characters entering their
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location.
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What we will need is the following:
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- An NPC typeclass that can react when someone enters.
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- A custom [Room](../Components/Objects.md#rooms) typeclass that can tell the NPC that someone entered.
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- We will also tweak our default `Character` typeclass a little.
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```python
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# in mygame/typeclasses/npcs.py (for example)
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from typeclasses.characters import Character
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class NPC(Character):
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"""
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A NPC typeclass which extends the character class.
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"""
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def at_char_entered(self, character, **kwargs):
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"""
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A simple is_aggressive check.
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Can be expanded upon later.
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"""
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if self.db.is_aggressive:
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self.execute_cmd(f"say Graaah! Die, {character}!")
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else:
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self.execute_cmd(f"say Greetings, {character}!")
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```
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```{sidebar} Passing extra information
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Note that we don't use the `**kwargs` property here. This can be used to pass extra information into hooks in your game and would be used when you make custom move commands. For example, if you `run` into the room, you could inform all hooks by doing `obj.move_to(..., running=True)`. Maybe your librarian NPC should have a separate reaction for people running into their library!
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We make sure to pass the `**kwargs` from the standard `at_object_receive` hook below.
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```
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Here we make a simple method on the `NPC`˙ called `at_char_entered`. We expect it to be called when a (player-)character enters the room. We don't actually set the `is_aggressive` [Attribute](../Components/Attributes.md) beforehand; we leave this up for the admin to activate in-game. if it's not set, the NPC is simply non-hostile.
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Whenever _something_ enters the `Room`, its [at_object_receive](DefaultObject.at_object_receive) hook will be called. So we should override it.
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```python
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# in mygame/typeclasses/rooms.py
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from evennia import utils
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# ...
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class Room(ObjectParent, DefaultRoom):
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# ...
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def at_object_receive(self, arriving_obj, source_location, **kwargs):
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if arriving_obj.account:
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# this has an active acccount - a player character
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for item in self.contents:
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# get all npcs in the room and inform them
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if utils.inherits_from(item, "typeclasses.npcs.NPC"):
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item.at_char_entered(arriving_obj, **kwargs)
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```
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```{sidebar} Universal Object methods
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Remember that Rooms are `Objects`, and other Objects have these same hooks. So an `at_object_receive` hook will fire for you when you pick something up (making you 'receive' it). Or for a box when putting something inside it, for example.
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```
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A currently puppeted Character will have an `.account` attached to it. We use that to know that the thing arriving is a Character. We then use Evennia's [utils.inherits_from](evennia.utils.utils.inherits_from) helper utility to get every NPC in the room can each of their newly created `at_char_entered` method.
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Make sure to `reload`.
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Let's create an NPC and make it aggressive. For the sake of this example, let's assume your name is "Anna" and that there is a room to the north of your current location.
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> create/drop Orc:typeclasses.npcs.NPC
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> north
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> south
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Orc says, Greetings, Anna!
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Now let's turn the orc aggressive.
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> set orc/is_aggressive = True
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> north
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> south
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Orc says, Graah! Die, Anna!
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That's one easily aggravated Orc! |