LambdaHack- A game engine library for roguelike dungeon crawlers

Safe HaskellNone




Representation and computation of visiblity of atomic commands by clients.




data PosAtomic Source #

The type representing visibility of atomic commands to factions, based on the position of the command, etc. Note that the server sees and smells all positions.


PosSight LevelId [Point]

whomever sees all the positions, notices

PosFidAndSight [FactionId] LevelId [Point]

observers and the faction notice

PosSmell LevelId [Point]

whomever smells all the positions, notices

PosFid FactionId

only the faction notices, server doesn't

PosFidAndSer (Maybe LevelId) FactionId

faction and server notices


only the server notices


everybody notices


never broadcasted, but sent manually

posUpdAtomic :: MonadStateRead m => UpdAtomic -> m PosAtomic Source #

Produce the positions where the atomic update takes place or, more generally, the conditions under which the update can be noticed by a client.

The goal of this mechanics is to ensure that atomic commands involving some positions visible by a client convey similar information as the client would get by directly observing the changes of the portion of server state limited to the visible positions. Consequently, when the visible commands are later applied to the client's state, the state stays consistent --- in sync with the server state and correctly limited by visiblity. There is some wiggle room both in what "in sync" and "visible" means and how they propagate through time.

E.g., UpdDisplaceActor in a black room between two enemy actors, with only one actor carrying a 0-radius light would not be distinguishable by looking at the state (or the screen) from UpdMoveActor of the illuminated actor, hence such UpdDisplaceActor should not be observable, but UpdMoveActor in similar cotext would be (or the former should be perceived as the latter). However, to simplify, we assign as strict visibility requirements to UpdMoveActor as to UpdDisplaceActor and fall back to UpdSpotActor (which provides minimal information that does not contradict state) if the visibility is lower.

posSfxAtomic :: MonadStateRead m => SfxAtomic -> m PosAtomic Source #

Produce the positions where the atomic special effect takes place.

breakUpdAtomic :: MonadStateRead m => UpdAtomic -> m [UpdAtomic] Source #

Decompose an atomic action that is outside a client's visiblity. The decomposed actions give less information that the original command, but some of them may fall within the visibility range of the client. The original action may give more information than even the total sum of all actions it's broken into. E.g., UpdMoveActor informs about the continued existence of the actor between moves vs popping out of existence and then back in.

This is computed in server's State from before performing the command.

seenAtomicCli :: Bool -> FactionId -> Perception -> PosAtomic -> Bool Source #

Given the client, its perception and an atomic command, determine if the client notices the command.

seenAtomicSer :: PosAtomic -> Bool Source #

Determine whether the server would see a command that has the given visibilty conditions.

Internal operations