VIVIA — Multiplayer Networking

Protocol

TCP-based protocol at 20 Hz with bincode serialization:

Client → Server

Packet	Description
Join	Player name, handshake
PlayerInput	Position, yaw, flying, sprinting
BlockBreak	Block coordinates
BlockPlace	Block coordinates + type
Attack	Melee reach distance
Chat	Message text
RequestChunks	Chunk coordinate list
DamageEntity	Entity ID + damage amount
PingRTT	Timestamp for RTT measurement

Server → Client

Packet	Description
Welcome	Player ID, spawn, seed, tick rate
Chunk	Block data (compressed)
PlayerUpdate	Other player positions
EntityBatch	Bulk mob updates
EntitySpawn / EntityDespawn	Mob lifecycle
BlockUpdate	Block changes from other players
StatsSync	Server-authoritative stats
CombatEvent	Damage, knockback, enrage
ServerTick	Day time, night, blood moon
PlayerList	Connected players
ServerChat	System/player messages

Anti-Cheat

• Name sanitisation — max 24 chars, no control characters
• Chat sanitisation — max 256 chars, control chars stripped
• Block coordinate validation — ±16,384 X/Z, 0..512 Y
• Position validation — finite, ±1,000,000 (rejects NaN/Inf/teleport bombs)
• Rate limiting — >120 packets/sec → disconnect
• Handshake timeout — 10s anti-slowloris
• Pending connection limit — 64 max pre-handshake

Client-Side Interpolation

Remote players and entities are interpolated between updates:

• Each update stores previous position + new position
• Interpolation factor t advances with delta time
• Position = lerp(prev, new, t) for smooth movement at any frame rate

Chunk Streaming

• View distance: 8 chunks radius
• Backpressure: max 4 chunks sent per tick per client
• Dedup: client sends ChunkAck, server skips already-sent chunks
• Request filtering: client doesn't re-request cached chunks

Server Architecture

• Authoritative: server owns all entity HP, positions, block state
• Broadcast: all state changes broadcast to all clients
• Per-entity sync: only entities within ENTITY_SYNC_RADIUS (48m) are synced
• Despawn radius: entities beyond 64m are despawned on client