MeshRenderDecomposition.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Containers/Array.h"
#include "CoreMinimal.h"
#include "GeometryBase.h"
#include "HAL/Platform.h"
#include "Templates/UniquePtr.h"
 
PREDECLARE_USE_GEOMETRY_CLASS(FDynamicMesh3);
class UMaterialInterface;
struct FComponentMaterialSet;
 
class FMeshRenderDecomposition
{
public:
 
    // Movable
    FMeshRenderDecomposition(FMeshRenderDecomposition&&) = default;
    FMeshRenderDecomposition& operator=(FMeshRenderDecomposition&&) = default;
    // TArray<TUniquePtr> member cannot be default-constructed (in this case we just make it NonCopyable)
    FMeshRenderDecomposition() = default;
    FMeshRenderDecomposition(const FMeshRenderDecomposition&) = delete;
    FMeshRenderDecomposition& operator=(const FMeshRenderDecomposition&) = delete;
 
    struct FGroup
    {
        TArray<int32> Triangles;
        UMaterialInterface* Material;
    };
    TArray<TUniquePtr<FGroup>> Groups;
 
 
    TArray<int32> TriangleToGroupMap;
 
    void Initialize(int32 Count)
    {
        Groups.SetNum(Count);
        for (int32 k = 0; k < Count; ++k)
        {
            Groups[k] = MakeUnique<FGroup>();
        }
    }
 
    int32 AppendGroup()
    {
        int32 N = Groups.Num();
        Groups.SetNum(N + 1);
        Groups[N] = MakeUnique<FGroup>();
        return N;
    }
 
    int32 Num() const
    {
        return Groups.Num();
    }
 
    bool IsGroup(int32 Index) const
    {
        return Groups[Index] != nullptr;
    }
 
    FGroup& GetGroup(int32 Index)
    {
        return *Groups[Index];
    }
 
    const FGroup& GetGroup(int32 Index) const
    {
        return *Groups[Index];
    }
 
    int32 GetGroupForTriangle(int32 TriangleID) const
    {
        return TriangleToGroupMap[TriangleID];
    }
 
    GEOMETRYFRAMEWORK_API void BuildAssociations(const FDynamicMesh3* Mesh);
 
 
    static GEOMETRYFRAMEWORK_API void BuildMaterialDecomposition(const FDynamicMesh3* Mesh, const FComponentMaterialSet* MaterialSet, FMeshRenderDecomposition& Decomp);
 
    static GEOMETRYFRAMEWORK_API void BuildChunkedDecomposition(const FDynamicMesh3* Mesh, const FComponentMaterialSet* MaterialSet, FMeshRenderDecomposition& Decomp, int32 MaxChunkSize = 1 << 14 /* 16k */ );
};