FMujocoSpecWrapper

Helper class to simplify building a MuJoCo mjSpec structure from Unreal Engine components.

Handles coordinate system conversion, unique naming, and resource management (VFS for meshes). Acts as a bridge between high-level UE components and low-level MuJoCo C API.

Attribute	Value
Kind	Class

Properties Functions

Properties

Public Properties

Property	Type	Description
Spec	mjSpec*
VFS	mjVFS*
MeshCacheSubDir	FString	Sub-directory name for mesh cache (set to articulation name).
CreatedBodyNames	TArray<FString>	storage of created body names for view reconstruction.

Spec

• Type: mjSpec*

VFS

• Type: mjVFS*

MeshCacheSubDir

Sub-directory name for mesh cache (set to articulation name).

• Type: FString

CreatedBodyNames

storage of created body names for view reconstruction.

• Type: TArray

Functions

Public Functions

General

Function	Returns	Description
FMujocoSpecWrapper()		Constructor.
CreateBody()	mjsBody*	Creates a body in the spec.
CreateFrame()	mjsFrame*	Creates a frame in the spec attached to a specific parent body.
AddMeshAsset()	FString	Registers a mesh asset in the spec and VFS.
AddPrimitiveGeom()	mjsGeom*	Adds a primitive geom to a body (Direct creation).
AddMeshGeom()	mjsGeom*	Adds a mesh geom to a body (Direct creation).
AddFreeJoint()	void	Adds a legacy free joint.
AddDefault()	void	Adds a default class from a component.
ReconstructViews()	TArray<BodyView>	Reconstructs implementation views for binding after compilation.
PrepareMeshForMuJoCo()	TArray<FString>	Prepares a static mesh for MuJoCo (exports OBJ, logs it).
GetUniqueName()	FString	Generates a unique name for a MuJoCo object to avoid collisions.

FMujocoSpecWrapper

Constructor.

• Signature: FMujocoSpecWrapper(mjSpec* InSpec, mjVFS* InVFS)

CreateBody

Creates a body in the spec.

• Signature: CreateBody(const FString& Name, const FString& ParentName, const FTransform& WorldTransform)
• Returns: mjsBody*

CreateFrame

Creates a frame in the spec attached to a specific parent body.

• Signature: CreateFrame(const FString& Name, mjsBody* ParentBody, const FTransform& WorldTransform)
• Returns: mjsFrame*

AddMeshAsset

Registers a mesh asset in the spec and VFS.

• Signature: AddMeshAsset(const FString& MeshName, const FString& FilePath, const FVector& Scale)
• Returns: FString

AddPrimitiveGeom

Adds a primitive geom to a body (Direct creation).

• Signature: AddPrimitiveGeom(mjsBody* Body, mjtGeom Type, const FVector& Size, const FVector4& RGBA)
• Returns: mjsGeom*

AddMeshGeom

Adds a mesh geom to a body (Direct creation).

• Signature: AddMeshGeom(mjsBody* Body, FTransform RelTrans, const FString& MeshAssetName, const FString& GeomNameSuffix, const FVector4& RGBA)
• Returns: mjsGeom*

AddFreeJoint

Adds a legacy free joint.

• Signature: AddFreeJoint(mjsBody* Body, const FString& JointName)

AddDefault

Adds a default class from a component.

• Signature: AddDefault(class UMjDefault* DefaultComp)

ReconstructViews

Reconstructs implementation views for binding after compilation.

• Signature: ReconstructViews(const mjModel* m, mjData* d, const FString& Prefix)
• Returns: TArray<BodyView>

PrepareMeshForMuJoCo

Prepares a static mesh for MuJoCo (exports OBJ, logs it).

• Signature: PrepareMeshForMuJoCo(UStaticMeshComponent* SMC, bool bComplexMeshRequired, float CoACDThreshold)
• Returns: TArray

GetUniqueName

Generates a unique name for a MuJoCo object to avoid collisions.

• Signature: GetUniqueName(const FString& BaseName, mjtObj Type, const AActor* ContextActor)
• Returns: FString