xra1

XRAI → Unreal Engine

Target: Unreal Engine 5.4+. Reference plugin ships Month 2 (deprioritized vs Unity + Three.js which ship earlier).

Ingestion contract

// C++
TSharedPtr<FXraiGraph> Graph = UXraiLoader::Parse(JsonText);
AActor* SceneRoot = UXraiSceneBuilder::Build(Graph, World);

// Blueprint
Parse XRAI (String) -> XRAI Graph
Build XRAI Scene (XRAI Graph, World) -> Actor

Mapping

XRAI	Unreal
entity.type = object.primitive, model_id = 0..5	StaticMeshActor with engine-content cube/sphere mesh
entity.type = object.glb + url	glTFRuntime plugin (open-source)
entity.type = object.light	APointLight / ASpotLight
entity.transform.position	SetActorLocation(FVector) — XRAI meters × 100 = Unreal cm
entity.transform.rotation (quat)	SetActorRotation(FQuat(x,y,z,w))
entity.transform.scale	SetActorScale3D(FVector)
entity.material.color	Dynamic material instance with base color
relation.type = parent-of	AttachToActor(...)

Unit + handedness conversion

• Unreal uses centimeters. Multiply XRAI position by 100.
• Unreal is left-handed Z-up. XRAI canonical is left-handed Y-up. Swap Y↔Z + negate one.
• Done once in the loader; scene code stays engine-native.

Plugin structure

XraiPlugin/
├── Source/
│   ├── Xrai/
│   │   ├── Private/
│   │   │   ├── XraiLoader.cpp
│   │   │   └── XraiSceneBuilder.cpp
│   │   ├── Public/
│   │   │   ├── XraiLoader.h
│   │   │   └── XraiSceneBuilder.h
│   │   └── Xrai.Build.cs
│   └── XraiEditor/
│       └── (asset import, preview widget)
├── Content/
│   └── Examples/
└── Xrai.uplugin

Distribution

• Epic Fab marketplace (free listing)
• GitHub source for modders
• MIT license

Status

• Plugin scaffold
• Primitives + GLB loading
• Blueprint bindings
• Sample project with “voice-to-XRAI-to-Unreal” demo

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