57 lines
1.9 KiB
C++
57 lines
1.9 KiB
C++
// Copyright Epic Games, Inc. All Rights Reserved.
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#pragma once
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#include "CoreMinimal.h"
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#include "PackedNormal.h"
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/**
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* Constructs a basis matrix for the axis vectors and returns the sign of the determinant
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*
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* @param XAxis - x axis (tangent)
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* @param YAxis - y axis (binormal)
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* @param ZAxis - z axis (normal)
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* @return sign of determinant either -1 or +1
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*/
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inline float GetBasisDeterminantSign(const FVector& XAxis, const FVector& YAxis, const FVector& ZAxis)
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{
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FMatrix Basis(
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FPlane(XAxis, 0),
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FPlane(YAxis, 0),
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FPlane(ZAxis, 0),
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FPlane(0, 0, 0, 1)
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);
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// RotDeterminant is the determinant of the upper left 3x3 matrix and equivalent to the full 4x4 determinant for this matrix
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// at one fourth the cost.
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return (Basis.RotDeterminant() < 0) ? -1.0f : +1.0f;
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}
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/**
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* Constructs a basis matrix for the axis vectors and returns the sign of the determinant
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*
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* @param XAxis - x axis (tangent)
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* @param YAxis - y axis (binormal)
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* @param ZAxis - z axis (normal)
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* @return sign of determinant either -127 (-1) or +1 (127)
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*/
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inline int8 GetBasisDeterminantSignByte(const FPackedNormal& XAxis, const FPackedNormal& YAxis, const FPackedNormal& ZAxis)
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{
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return GetBasisDeterminantSign(XAxis.ToFVector(), YAxis.ToFVector(), ZAxis.ToFVector()) < 0 ? -127 : 127;
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}
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/**
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* Given 2 axes of a basis stored as a packed type, regenerates the y-axis tangent vector and scales by z.W
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* @param XAxis - x axis (tangent)
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* @param ZAxis - z axis (normal), the sign of the determinant is stored in ZAxis.W
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* @return y axis (binormal)
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*/
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template<typename VectorType>
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inline FVector GenerateYAxis(const VectorType& XAxis, const VectorType& ZAxis)
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{
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static_assert(std::is_same_v<VectorType, FPackedNormal> ||
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std::is_same_v<VectorType, FPackedRGBA16N>, "ERROR: Must be FPackedNormal or FPackedRGBA16N");
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FVector x = XAxis.ToFVector();
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FVector4 z = ZAxis.ToFVector4();
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return (FVector(z) ^ x) * z.W;
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}
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