UMjFlexcomp

Component representing a MuJoCo flexcomp deformable body.

Flexcomp generates a deformable soft body: ropes (dim=1), cloth (dim=2), or volumetric (dim=3). At spec registration, it expands into a flex element plus child bodies with slider joints for non-pinned vertices.

Attribute	Value
Kind	Class
UE Macro	UCLASS
Inherits	UMjComponent
Blueprint Spawnable	✅ Yes

Properties Functions

Properties

Public Properties

Property	Type	Description
Type	EMjFlexcompType
Dim	int32
DofType	EMjFlexcompDof
Count	FIntVector
Spacing	FVector
Mass	float
InertiaBox	float
Radius	float
Rgba	FLinearColor
Scale	FVector
bRigid	bool
bFlatSkin	bool
MeshFile	FString
PointData	TArray<double>
ElementData	TArray<int32>
ConType	int32
ConAffinity	int32
ConDim	int32
Priority	int32
Margin	float
Gap	float
SelfCollide	int32
bInternal	bool
Friction	TArray<float>	Contact friction: {tangential, torsional, rolling}.
SolMix	float
ContactSolRef	TArray<float>	Contact solref: {time_constant, damping_ratio}. Leave empty for MuJoCo defaults.
ContactSolImp	TArray<float>	Contact solimp: 5-element impedance vector.
EdgeStiffness	float
EdgeDamping	float
bEdgeEquality	bool	Emit equality constraints per edge. Pairs with EdgeSolRef/EdgeSolImp.
EdgeSolRef	TArray<float>	Edge solref: {time_constant, damping_ratio}. Only has effect when bEdgeEquality=true.
EdgeSolImp	TArray<float>	Edge solimp: 5-element impedance vector. Only has effect when bEdgeEquality=true.
Young	float
Poisson	float
Damping	float
Thickness	float
Elastic2D	int32	2D passive forces mode: 0=none, 1=bending, 2=stretching, 3=both.
PinIds	TArray<int32>
PinGridRange	TArray<int32>

Type

• Type: EMjFlexcompType
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp

Dim

• Type: int32
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp

DofType

• Type: EMjFlexcompDof
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp

Count

• Type: FIntVector
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp

Spacing

• Type: FVector
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp

Mass

Override-enabled (bOverride_Mass)

• Type: float
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp

InertiaBox

Override-enabled (bOverride_InertiaBox)

• Type: float
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp

Radius

Override-enabled (bOverride_Radius)

• Type: float
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp

Rgba

Override-enabled (bOverride_Rgba)

• Type: FLinearColor
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp

Scale

Override-enabled (bOverride_Scale)

• Type: FVector
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp

bRigid

• Type: bool
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp

bFlatSkin

• Type: bool
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp

MeshFile

• Type: FString
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp

PointData

• Type: TArray
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Direct

ElementData

• Type: TArray
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Direct

ConType

Override-enabled (bOverride_ConType)

• Type: int32
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Contact

ConAffinity

Override-enabled (bOverride_ConAffinity)

• Type: int32
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Contact

ConDim

Override-enabled (bOverride_ConDim)

• Type: int32
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Contact

Priority

Override-enabled (bOverride_Priority)

• Type: int32
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Contact

Margin

Override-enabled (bOverride_Margin)

• Type: float
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Contact

Gap

Override-enabled (bOverride_Gap)

• Type: float
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Contact

SelfCollide

Override-enabled (bOverride_SelfCollide)

• Type: int32
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Contact

bInternal

Override-enabled (bOverride_Internal)

• Type: bool
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Contact

Friction

Contact friction: {tangential, torsional, rolling}.

• Type: TArray
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Contact
• Notes: Override-enabled (bOverride_Friction)

SolMix

Override-enabled (bOverride_SolMix)

• Type: float
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Contact

ContactSolRef

Contact solref: {time_constant, damping_ratio}. Leave empty for MuJoCo defaults.

• Type: TArray
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Contact
• Notes: Override-enabled (bOverride_ContactSolRef)

ContactSolImp

Contact solimp: 5-element impedance vector.

• Type: TArray
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Contact
• Notes: Override-enabled (bOverride_ContactSolImp)

EdgeStiffness

Override-enabled (bOverride_EdgeStiffness)

• Type: float
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Edge

EdgeDamping

Override-enabled (bOverride_EdgeDamping)

• Type: float
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Edge

bEdgeEquality

Emit equality constraints per edge. Pairs with EdgeSolRef/EdgeSolImp.

• Type: bool
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Edge
• Notes: Override-enabled (bOverride_EdgeEquality)

EdgeSolRef

Edge solref: {time_constant, damping_ratio}. Only has effect when bEdgeEquality=true.

• Type: TArray
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Edge
• Notes: Override-enabled (bOverride_EdgeSolRef)

EdgeSolImp

Edge solimp: 5-element impedance vector. Only has effect when bEdgeEquality=true.

• Type: TArray
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Edge
• Notes: Override-enabled (bOverride_EdgeSolImp)

Young

Override-enabled (bOverride_Young)

• Type: float
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Elasticity

Poisson

Override-enabled (bOverride_Poisson)

• Type: float
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Elasticity

Damping

Override-enabled (bOverride_Damping)

• Type: float
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Elasticity

Thickness

Override-enabled (bOverride_Thickness)

• Type: float
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Elasticity

Elastic2D

2D passive forces mode: 0=none, 1=bending, 2=stretching, 3=both.

• Type: int32
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Elasticity
• Notes: Override-enabled (bOverride_Elastic2D)

PinIds

• Type: TArray
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Pin

PinGridRange

• Type: TArray
• Editor: ✏️ EditAnywhere
• Blueprint: 🔵 ReadWrite
• Category: MuJoCo|Flexcomp|Pin

Private Properties

Property	Type	Description
bIsRegistered	bool	Set once RegisterToSpec succeeds — prevents double-registration from
RawToWelded	TArray<int32>	Remap from raw UE vertex index → welded MuJoCo flex vertex index.
NumRenderVerts	int32	Number of raw UE vertices.

bIsRegistered

Set once RegisterToSpec succeeds — prevents double-registration from

• Type: bool

RawToWelded

Remap from raw UE vertex index → welded MuJoCo flex vertex index.

• Type: TArray

NumRenderVerts

Number of raw UE vertices.

• Type: int32

Functions

Private Functions

General

Function	Returns	Description
CaptureRenderData()	void	Captures raw UE vertex data (UVs, tangents, indices) from the child
BuildFlexcompXml()	FString	Serializes this flexcomp's properties back to an MJCF fragment.
ExportMeshToVFS()	FString	Exports the child StaticMeshComponent's mesh to an OBJ file in the wrapper's VFS.

CaptureRenderData

Captures raw UE vertex data (UVs, tangents, indices) from the child

• Signature: CaptureRenderData()

BuildFlexcompXml

Serializes this flexcomp's properties back to an MJCF fragment.

• Signature: BuildFlexcompXml(const FString& MeshAssetName)
• Returns: FString

ExportMeshToVFS

Exports the child StaticMeshComponent's mesh to an OBJ file in the wrapper's VFS.

• Signature: ExportMeshToVFS(class FMujocoSpecWrapper& Wrapper)
• Returns: FString