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Approaches to replicate Unreal Engine's TMap

Sat, 14 Jun 2025 00:00:00 +0000

Introduction #

If you ever attempt to put a Replicated specifier on your UPROPERTY with TMap, your IDE or compiler might yell at you like this:

Why can’t TMap be replicated by Unreal? #

Unreal’s built-in replication only supports certain types that the replication system knows how to serialize. This includes basic primitives, some containers like TArray, FVector, or custom structs containing UPROPERTY fields.

Networked Deterministic Array Shuffle in Unreal Engine

Fri, 13 Jun 2025 00:00:00 +0000

Introduction #

Sometimes, you want to do a deterministic shuffle of an array for purposes like gacha mechanics, or in my case, replicating the Spin the Wheel minigame in Coral Island!

At the time this feature was developed, it hadn’t yet been made to work with multiplayer. Even though Coral Island is a co-op game, not a competitive one, Unreal Engine still adopts a server-authoritative multiplayer model.