MirrorMatrix.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreTypes.h"
#include "Math/Plane.h"
#include "Math/Matrix.h"
 
namespace UE {
namespace Math {
 
 /**
 * Mirrors a point about an arbitrary plane 
 */
template<typename T>
struct TMirrorMatrix
    : public TMatrix<T>
{
public:
 
    /** 
     * Constructor. Updated for the fact that our FPlane uses Ax+By+Cz=D.
     * 
     * @param Plane source plane for mirroring (assumed normalized)
     */
    TMirrorMatrix( const TPlane<T>& Plane );
 
    // Conversion to other type.
    template<typename FArg, TEMPLATE_REQUIRES(!std::is_same_v<T, FArg>)>
    explicit TMirrorMatrix(const TMirrorMatrix<FArg>& From) : TMatrix<T>(From) {}
};
 
template<typename T>
FORCEINLINE TMirrorMatrix<T>::TMirrorMatrix( const TPlane<T>& Plane ) :
FMatrix(
    TPlane<T>( -2.f*Plane.X*Plane.X + 1.f,      -2.f*Plane.Y*Plane.X,       -2.f*Plane.Z*Plane.X,       0.f ),
    TPlane<T>( -2.f*Plane.X*Plane.Y,            -2.f*Plane.Y*Plane.Y + 1.f, -2.f*Plane.Z*Plane.Y,       0.f ),
    TPlane<T>( -2.f*Plane.X*Plane.Z,            -2.f*Plane.Y*Plane.Z,       -2.f*Plane.Z*Plane.Z + 1.f, 0.f ),
    TPlane<T>(  2.f*Plane.X*Plane.W,             2.f*Plane.Y*Plane.W,        2.f*Plane.Z*Plane.W,       1.f ) )
{
    //check( FMath::Abs(1.f - Plane.SizeSquared()) < KINDA_SMALL_NUMBER && TEXT("not normalized"));
}
 
} // namespace Math
} // namespace UE
 
UE_DECLARE_LWC_TYPE(MirrorMatrix, 44);
 
template<> struct TIsUECoreVariant<FMirrorMatrix44f> { enum { Value = true }; };
template<> struct TIsUECoreVariant<FMirrorMatrix44d> { enum { Value = true }; };