MjOrientationUtils

If true, angles (euler, axisangle) are in degrees. If false (default), radians.

bool bAngleInDegrees = false; / Euler rotation sequence, e.g. "xyz", "XYZ", "zyx". Default "xyz" (intrinsic). */ FString EulerSeq = TEXT("xyz"); / Base directory for mesh file paths (from meshdir attribute). Empty = same dir as XML. / FString MeshDir; / Base directory for all asset paths (from assetdir attribute). Overrides meshdir for meshes if both present. / FString AssetDir; / If true, joints/tendons with a range attribute are automatically treated as limited (from autolimits). */ bool bAutoLimits = false; / Helper: resolve a relative mesh path using MeshDir / AssetDir with the given XML directory as the root. / FString ResolveMeshPath(const FString& RelPath, const FString& XmlDir) const { if (RelPath.IsEmpty()) return RelPath; // AssetDir takes priority for mesh lookups FString Base = AssetDir.IsEmpty() ? MeshDir : AssetDir; if (Base.IsEmpty()) Base = XmlDir; return FPaths::Combine(Base, RelPath); } }; /* Centralized utility for converting MuJoCo orientation attributes to quaternions. MuJoCo supports 5 orientation representations on spatial-frame elements: quat, axisangle, euler, xyaxes, zaxis Only one should be specified per element. Priority order (matching MuJoCo): quat > axisangle > euler > xyaxes > zaxis All functions produce MuJoCo-frame quaternions (w, x, y, z). Use MjUtils::MjToUERotation() to convert to Unreal frame afterwards.

Attribute	Value
Kind	Class

Properties Functions

Properties

Public Properties

Property	Type	Description
Lowercase	*

Lowercase

• Type: *

Private Properties

Property	Type	Description
Result	** Multiply two quaternions:

Result

• Type: ** Multiply two quaternions:

Functions

Public Functions

General

Function	Returns	Description
ParseCompilerSettings()	FMjCompilerSettings	Parse the element from an MJCF XML root and extract orientation-related settings.
OrientationToMjQuat()	bool	Read orientation attributes from an XML element and convert to a MuJoCo-frame quaternion.
AxisAngleToQuat()	void	Convert axis-angle (x, y, z, angle_rad) to quaternion. Axis need not be normalized.
EulerToQuat()	void	Convert Euler angles to quaternion given a 3-character euler sequence string.
XYAxesToQuat()	void	Convert xyaxes (6 values: x-axis 3, y-axis 3) to quaternion. Y is orthogonalized.
ZAxisToQuat()	void	Convert zaxis (3 values) to quaternion via minimal rotation from (0,0,1).

ParseCompilerSettings

Parse the element from an MJCF XML root and extract orientation-related settings.

• Signature: ParseCompilerSettings(const FXmlNode* RootNode)
• Returns: FMjCompilerSettings

OrientationToMjQuat

Read orientation attributes from an XML element and convert to a MuJoCo-frame quaternion.

• Signature: OrientationToMjQuat(const FXmlNode* Node, const FMjCompilerSettings& Settings, double OutQuat[4])
• Returns: bool

AxisAngleToQuat

Convert axis-angle (x, y, z, angle_rad) to quaternion. Axis need not be normalized.

• Signature: AxisAngleToQuat(double x, double y, double z, double AngleRad, double OutQuat[4])

EulerToQuat

Convert Euler angles to quaternion given a 3-character euler sequence string.

• Signature: EulerToQuat(double e1, double e2, double e3, const FString& EulerSeq, double OutQuat[4])

XYAxesToQuat

Convert xyaxes (6 values: x-axis 3, y-axis 3) to quaternion. Y is orthogonalized.

• Signature: XYAxesToQuat(const double XYAxes[6], double OutQuat[4])

ZAxisToQuat

Convert zaxis (3 values) to quaternion via minimal rotation from (0,0,1).

• Signature: ZAxisToQuat(const double ZAxis[3], double OutQuat[4])

Private Functions

General

Function	Returns	Description
ElementalRotQuat()	void	Create a quaternion for rotation around a single axis (0=x, 1=y, 2=z) by AngleRad.
QuatMul()	void	Multiply two quaternions: Result = A * B (Hamilton product). All in w,x,y,z order.
QuatNormalize()	void	Normalize a quaternion in-place.
RotMatToQuat()	void	Convert a 3x3 rotation matrix (row-major) to quaternion (w,x,y,z).

ElementalRotQuat

Create a quaternion for rotation around a single axis (0=x, 1=y, 2=z) by AngleRad.

• Signature: ElementalRotQuat(int AxisIndex, double AngleRad, double OutQuat[4])

QuatMul

Multiply two quaternions: Result = A * B (Hamilton product). All in w,x,y,z order.

• Signature: QuatMul(const double A[4], const double B[4], double Result[4])

QuatNormalize

Normalize a quaternion in-place.

• Signature: QuatNormalize(double Q[4])

RotMatToQuat

Convert a 3x3 rotation matrix (row-major) to quaternion (w,x,y,z).

• Signature: RotMatToQuat(const double R[9], double OutQuat[4])