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Plugin Overview

Modular Building System is a modular building plugin for Unreal Engine, designed for survival, sandbox, base-building, and multiplayer games.

The plugin's core systems are implemented in C++, while commonly used components, data assets, events, and extension interfaces are exposed to Blueprints. Standard building workflows can be completed in Blueprint-only projects without modifying the plugin source code.

Core Features

  • HISM and Actor rendering modes
  • Building management based on Building Entities and Chunks
  • Building preview, placement, movement, and removal
  • Static Mesh Socket snapping
  • Structural support and collapse detection
  • Server-authoritative multiplayer building
  • Extensible cost, permission, and effect systems

Core Architecture

Building Entity

Each placed building is represented by a Building Entity that stores information such as:

  • Entity ID
  • World Transform
  • Building Asset ID
  • Owner
  • Runtime Attributes
  • Gameplay Tags

A Building Entity represents the logical data of a building and is not the same as an Unreal Actor.

Whether a building is rendered as an HISM Instance or an independent Actor, its data is managed through the same Building Entity system.

Chunk System

Buildings are assigned to Chunks according to their world positions.

Each Chunk manages the building entities, visual objects, instance mappings, and replicated data within an area, reducing the cost of querying and maintaining large building environments.

Rendering Modes

The plugin supports two primary rendering modes:

  • HISM: Suitable for large numbers of repeated static modules, such as foundations, walls, floors, and roofs.
  • Actor: Suitable for buildings that require independent logic, such as doors, containers, workbenches, and functional devices.

Both modes can be used together in the same project.

Building Workflow

The standard building workflow is:

Select a Building Data Asset
→ Create a building preview
→ Calculate placement and snapping
→ Validate placement conditions
→ Submit a request to the server
→ Perform final server validation
→ Create and replicate the Building Entity
→ Create an HISM Instance or Actor

Client-side previews are used only for interaction feedback. The final building result is always determined by server validation.

Extensibility

Projects can integrate their own Blueprint or C++ systems for:

  • Inventory and resources
  • Currency and building costs
  • Building permissions
  • Niagara effects and sounds
  • UI notifications
  • Custom building Actors

The plugin provides the base workflow and extension interfaces without requiring a specific inventory, currency, or interaction system.

Suitable Projects

The plugin is suitable for:

  • Survival and sandbox games
  • Base-building games
  • Tower defense games
  • Cooperative multiplayer games
  • Large-scale modular building systems