UKismetMathLibrary::Matrix_Mirror

function Engine Blueprint Since 4.0

#include "Kismet/KismetMathLibrary.h"

Access: public Specifiers: staticBlueprintPure

Description

Mirrors a transform matrix across a given axis and flips one local axis to maintain correct handedness. Used for producing mirrored skeletal animations or planar reflections.

Caveats & Gotchas

• Mirroring inverts the winding order of triangles — if you use the result to transform geometry, you must also flip face culling (e.g. EWindingMode) or the mesh will appear inside-out.
• MirrorAxis and FlipAxis must not be the same axis; passing identical values produces a degenerate transform rather than a no-op.

Signature

static UE_INL_API FMatrix Matrix_Mirror(const FMatrix& M, TEnumAsByte<EAxis::Type> MirrorAxis, TEnumAsByte<EAxis::Type> FlipAxis)

Parameters

Name	Type	Description	Default
M	const FMatrix&	The transform matrix to mirror.	—
MirrorAxis	TEnumAsByte<EAxis::Type>	The world axis to mirror across.	—
FlipAxis	TEnumAsByte<EAxis::Type>	One of the local axes to flip after mirroring to correct handedness.	—

Return Type

FMatrix

Example

Mirror a bone transform across the YZ plane (X axis) C++

FMatrix BoneMatrix = BoneTransform.ToMatrixWithScale();
FMatrix Mirrored = UKismetMathLibrary::Matrix_Mirror(
    BoneMatrix,
    EAxis::X,   // mirror across the X axis (YZ plane)
    EAxis::Y    // flip Y to preserve handedness
);
FTransform MirroredTransform = FTransform(Mirrored);

Version History

Introduced in: 4.0

Version	Status	Notes
5.6	stable	—

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