Runtime Asset Import

Overview

Runtime Asset Import is an Unreal Engine code plugin that imports static 3D mesh data at runtime on Windows (Win64). It accepts a file path or an in-memory byte array and constructs a hierarchy of Dynamic Mesh Components or Procedural Mesh Components. DynamicMesh is the recommended path.

Supported Environment

• Unreal Engine 5.4 through 5.8, as verified in MarketplaceListing.md
• Windows Win64 editor and packaged applications
• Static geometry only

Other desktop platforms, mobile platforms, and consoles are not supported by the bundled dependency.

Features

• Synchronous runtime import from a local file or memory
• Blueprint and C++ APIs
• DynamicMeshComponent construction (recommended)
• ProceduralMeshComponent construction
• Hierarchical node transforms and multiple mesh sections
• Diffuse/base color and one embedded texture per material
• Collision generation on constructed components
• Assimp 6.0.5 built from the official source tag

The plugin intentionally has no StaticMesh construction API, latent or asynchronous API, or URL downloader.

Installation from Fab

1. Acquire Runtime Asset Import in Fab.
2. In the Epic Games Launcher, install the plugin for a supported Unreal Engine version.
3. Open the project and enable Runtime Asset Import under Edit > Plugins if it is not already enabled.
4. Restart the editor when prompted.

The packaged plugin already contains the required Win64 Assimp DLL. CMake is not required for normal use.

Installation from Source

1. Place this repository at <Project>/Plugins/RuntimeAssetImport.
2. Generate project files or open the .uproject and accept the rebuild prompt.
3. Build the project for Win64.

For a Git checkout:

git clone https://github.com/metyatech/RuntimeAssetImportPlugin.git Plugins/RuntimeAssetImport

Blueprint Quick Start

1. Create a file path for a local FBX, OBJ, glTF/GLB, or DAE file.
2. Call Construct Dynamic Mesh Component from Asset File.
3. Pass an owning Actor and a Parent Material that provides the required parameters below.
4. Handle the Success and Failure execution outputs.
5. Use the returned root Dynamic Mesh Component. Child nodes are attached beneath it.

For memory input, call Load Mesh from Asset Data, then pass the returned mesh data to Construct Dynamic Mesh Component from Mesh Data.

C++ Quick Start

#include "AssetConstructor.h"

EConstructDynamicMeshComponentFromAssetFileResult Result =
    EConstructDynamicMeshComponentFromAssetFileResult::Failure;

UDynamicMeshComponent* RootComponent =
    UAssetConstructor::ConstructDynamicMeshComponentFromAssetFile(
        FilePath,
        ParentMaterial,
        OwnerActor,
        Result);

if (Result != EConstructDynamicMeshComponentFromAssetFileResult::Success ||
    RootComponent == nullptr)
{
    // Report or recover from the failed import.
}

To separate import from construction:

#include "AssetLoader.h"

ELoadMeshFromAssetFileResult LoadResult = ELoadMeshFromAssetFileResult::Failure;
const FLoadedMeshData MeshData = UAssetLoader::LoadMeshFromAssetFile(FilePath, LoadResult);

if (LoadResult == ELoadMeshFromAssetFileResult::Success)
{
    UDynamicMeshComponent* RootComponent =
        UAssetConstructor::ConstructDynamicMeshComponentFromMeshData(
            MeshData, ParentMaterial, OwnerActor);
}

Parent Material Requirements

Construction requires a Parent Material with these parameters:

Parameter	Type	Purpose
TextureBlendIntensityForBaseColor	Scalar	Selects the base-color texture contribution.
BaseColor4	Vector	Supplies the imported diffuse/base color.
BaseColorTexture	Texture2D	Supplies the imported embedded texture.

The bundled /RuntimeAssetImport/AssetImporterMeshMaterial satisfies this contract. A Parent Material missing any required parameter is rejected without creating a partial component hierarchy.

Tested File Formats

Automated tests directly import:

• FBX
• OBJ
• glTF
• GLB
• DAE (Collada)

Assimp supports additional formats, but only the formats listed above are claimed as tested for this release.

Blueprint API

The plugin exposes exactly six Blueprint-callable functions:

• LoadMeshFromAssetFile
• LoadMeshFromAssetData
• ConstructDynamicMeshComponentFromMeshData
• ConstructDynamicMeshComponentFromAssetFile
• ConstructProceduralMeshComponentFromMeshData
• ConstructProceduralMeshComponentFromAssetFile

Synchronous Import Warning

All import and construction functions are synchronous. A large or complex file blocks the calling thread until parsing and construction finish. Schedule calls at an acceptable point in the application flow and validate input size before importing untrusted data. The plugin does not provide latent, asynchronous, or URL-loading APIs.

Known Limitations

• Win64 only
• Static geometry only; no skeletal meshes, animations, morph targets, or LOD import
• External texture references are not loaded
• Only the first material texture, first UV channel, and first vertex-color channel are used
• Runtime-created meshes are local and are not automatically replicated
• ProceduralMeshComponent can cause movement or network issues when independently created by multiplayer peers; DynamicMeshComponent is recommended
• Input paths must refer to local files accessible to the application

Running Tests

Install the plugin in an Unreal project, then run:

UnrealEditor-Cmd.exe <Project>.uproject -ExecCmds="Automation RunTests RuntimeAssetImport; Quit" -unattended -nop4 -nosplash

The RuntimeAssetImportSample repository is the CI test host. It is not an end-user example project for the initial Fab release.

Rebuilding the Bundled Assimp Dependency

Normal users do not need to rebuild Assimp. Maintainers can reproduce the bundled Visual Studio 2022 v143, Win64, Release build from official Assimp tag v6.0.5 and commit 392a658f9c271be965271f45e7521a1b80ea4392:

pwsh -NoProfile -File .\BuildAssimpForPlugin.ps1

The script validates the source revision, headers, binary architecture, dependencies, exports, generated test assets, and hashes before replacing the repository artifacts. See BUILD-INFO.json.

Creating a Fab Submission Package

Create and validate the UE 5.4 package with:

pwsh -NoProfile -File .\PackageForFab.ps1 -EngineVersion 5.4

The output contains a single RuntimeAssetImport directory and excludes tests, internal files, debug symbols, and build artifacts. Use -OutputDirectory <Path> to place generated output outside the repository.

Licensing

The current source is source-available under the conditions in LICENSE. Copies acquired through Fab are governed by the applicable Fab Standard License and Fab End User License Agreement. Earlier commits or releases explicitly distributed under MIT remain under the MIT license recorded in LICENSE-MIT-LEGACY.

Third-Party Software

The bundled Assimp DLL and import library were built by the publisher from the official Assimp 6.0.5 source tag; they are not described as official distributed binaries. Assimp and its bundled components retain their respective licenses. See THIRD_PARTY_NOTICES.md and Source/ThirdParty/assimp/LICENSES.

Support

Report reproducible problems through GitHub Issues. Include the Unreal Engine version, input format, whether the failure occurs in editor or a packaged Win64 build, and a minimal reproduction when possible.