LayoutUV.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Allocator2D.h"
#include "Containers/Array.h"
#include "CoreMinimal.h"
#include "Math/UnrealMathSSE.h"
#include "Math/Vector2D.h"
#include "MeshUtilitiesCommon.h"
 
template <typename T> class TAtomic;
 
struct FMeshChart
{
    uint32      FirstTri;
    uint32      LastTri;
    
    FVector2f   MinUV;
    FVector2f   MaxUV;
    
    float       UVArea;
    FVector2f   UVScale;
    FVector2f   WorldScale;
    
    float       UVLengthSum;
    float       WorldLengthSum;
 
    FVector2f   PackingScaleU;
    FVector2f   PackingScaleV;
    FVector2f   PackingBias;
 
    int32       Join[4];
 
    int32       Id; // Store a unique id so that we can come back to the initial Charts ordering when necessary
};
 
struct FOverlappingCorners;
 
class FLayoutUV
{
public:
 
    struct IMeshView
    {
        virtual ~IMeshView() {}
 
        virtual uint32      GetNumIndices() const = 0;
        virtual FVector3f   GetPosition(uint32 Index) const = 0;
        virtual FVector3f   GetNormal(uint32 Index) const = 0;
        virtual FVector2f   GetInputTexcoord(uint32 Index) const = 0;
 
        virtual void        InitOutputTexcoords(uint32 Num) = 0;
        virtual void        SetOutputTexcoord(uint32 Index, const FVector2f& Value) = 0;
    };
 
    MESHUTILITIESCOMMON_API FLayoutUV( IMeshView& InMeshView );
    void SetVersion( ELightmapUVVersion Version ) { LayoutVersion = Version; }
    MESHUTILITIESCOMMON_API int32 FindCharts( const FOverlappingCorners& OverlappingCorners );
    MESHUTILITIESCOMMON_API bool FindBestPacking( uint32 InTextureResolution );
    MESHUTILITIESCOMMON_API void CommitPackedUVs();
 
    static MESHUTILITIESCOMMON_API void LogStats();
    static MESHUTILITIESCOMMON_API void ResetStats();
private:
    IMeshView& MeshView;
    ELightmapUVVersion LayoutVersion;
 
    TArray< FVector2f > MeshTexCoords;
    TArray< uint32 > MeshSortedTris;
    TArray< FMeshChart > MeshCharts;
    uint32 PackedTextureResolution;
 
    struct FChartFinder;
    struct FChartPacker;
 
    static MESHUTILITIESCOMMON_API TAtomic<uint64> FindBestPackingCount;
    static MESHUTILITIESCOMMON_API TAtomic<uint64> FindBestPackingCycles;
    static MESHUTILITIESCOMMON_API TAtomic<uint64> FindBestPackingEfficiency;
};