FJoinHead

What the join stream's first frame says: the position S, the checkpoint there, and where the save's parts lie.

Declaration

struct FJoinHead

Header: #include "Native/Net/NetJoin.h"
Module: PublicDependencyModuleNames.Add("OrreryTerrainCore"); in your module’s Build.cs.
Stability: Experimental: supported, may change in a minor version, with a changelog line.

Description

The joiner checks StateHash and SyncHash right after its load, so a wrong snapshot is found before any record applies.

Properties

Name	Type	Default	Meaning
`Seq`	`FNetSeq`	`0`	S: the newest record the snapshot includes; the joiner's replica expects S + 1 next.
`SyncHash`	`uint64_t`	`0`	FTerrainWorld::SyncHash at S.
`SculptDigest`	`uint64_t`	`0`	The authority's `FSculptReplayer::Digest` at S (the joiner's seed).
`NextFeatureId`	`FFeatureId`	`0`	At S, burnt ids included.
`StateHash`	`uint64_t`	`0`	FTerrainSerialization::StateHash at S.
`FileSize`	`uint64_t`	`0`	Bytes of the save.
`FileHash`	`uint64_t`	`0`	The save's trailer (FTerrainSaveInfo::FileHash).
`CodeAreaOffset`	`uint64_t`	`0`	Where the sculpt codes start in the save; the rest is the load set.
`CodeAreaSize`	`uint64_t`	`0`	—
`PageTiles`	`uint8_t`	`0`	The joiner page edge the codes were ordered by (`FJoinStreamConfig::PageTiles`, at most 255). A paged joiner with another refuses the join (`EJoinLoad::PageTilesMismatch`).
`Strokes`	`std::vector<FJoinOpenStroke>`	—	Every stroke open at S, several authors' at once, ascending (Author, Stroke): the order is canonical, so two writers at the same S send the same head. Empty when none is open.
`Masks`	`std::vector<FJoinMaskRef>`	—	The brush masks the stream's mask frames carry, ascending hash, at most kJoinMaxMaskBytes in all: the masks the session announced at or before S that the joiner does not hold, as `FJoinStreamConfig::Masks` names them.
`Limits`	`FSculptLimits`	—	The authority's sculpt limits at S. The joiner's replica checks and replays every record under these, never under its own settings: a record the authority accepted applies the same everywhere, KeepOutMargin_mm included, so a client configured with other limits cannot desync (StartJoinReplica).
`CacheUse`	`EJoinCacheUse`	`EJoinCacheUse::None`	How this stream uses the save the joiner holds.