GeometryCollectionRenderData.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "RawIndexBuffer.h"
#include "Rendering/ColorVertexBuffer.h"
#include "Rendering/NaniteResources.h"
#include "Rendering/PositionVertexBuffer.h"
#include "Rendering/StaticMeshVertexBuffer.h"
 
class FGeometryCollection;
class UGeometryCollection;
 
 
class FBoneMapVertexBuffer : public FVertexBuffer
{
public:
    ~FBoneMapVertexBuffer();
 
    void Init(TArray<uint16> const& InBoneMap, bool bInNeedsCPUAccess = true);
    void Serialize(FArchive& Ar, bool bInNeedsCPUAccess);
    FRHIShaderResourceView* GetSRV() const { return VertexBufferSRV; }
    
    FORCEINLINE uint16& BoneIndex(uint32 VertexIndex) const
    {
        checkSlow(VertexIndex < NumVertices);
        return *(uint16*)(Data + VertexIndex * PixelFormatStride);
    }
 
    SIZE_T GetAllocatedSize() const { return (BoneMapData != nullptr) ? BoneMapData->GetResourceSize() : 0; }
 
protected:
    void CleanUp();
    void AllocateData(bool bInNeedsCPUAccess = true);
    void ResizeBuffer(uint32 InNumVertices);
 
    void InitRHI(FRHICommandListBase& RHICmdList) override;
    void ReleaseRHI() override;
 
    static const EPixelFormat PixelFormat = PF_R16_UINT;
    static const uint32 PixelFormatStride = 2;
 
private:
    uint32 NumVertices = 0;
    bool bNeedsCPUAccess = true;
    FShaderResourceViewRHIRef VertexBufferSRV = nullptr;
    FStaticMeshVertexDataInterface* BoneMapData = nullptr;
    uint8* Data = nullptr;
};
 
struct FGeometryCollectionMeshResources
{
    FRawStaticIndexBuffer IndexBuffer;
    FPositionVertexBuffer PositionVertexBuffer;
    FStaticMeshVertexBuffer StaticMeshVertexBuffer;
    FColorVertexBuffer ColorVertexBuffer;
    FBoneMapVertexBuffer BoneMapVertexBuffer;
 
    void InitResources(UGeometryCollection const& Owner);
    void ReleaseResources();
    void Serialize(FArchive& Ar);
};
 
struct FGeometryCollectionMeshElement
{
    int16 TransformIndex;
    uint8 MaterialIndex;
    uint8 bIsInternal;
    uint32 TriangleStart;
    uint32 TriangleCount;
    uint32 VertexStart;
    uint32 VertexEnd;
 
    friend FArchive& operator<<(FArchive& Ar, FGeometryCollectionMeshElement& Item)
    {
        Ar << Item.TransformIndex << Item.MaterialIndex << Item.bIsInternal << Item.TriangleStart << Item.TriangleCount << Item.VertexStart << Item.VertexEnd;
        return Ar;
    }
};
 
struct FGeometryCollectionMeshDescription
{
    uint32 NumVertices = 0;
    uint32 NumTriangles = 0;
 
    // Info on grouped material sections within vertex buffers. 
    // A section has a uniform material index and can contain multiple per-bone subsections.
    TArray<FGeometryCollectionMeshElement> Sections;
    // Info on grouped material sections within vertex buffers but with internal faces added by the fracture tool removed.
    TArray<FGeometryCollectionMeshElement> SectionsNoInternal;
    // Info on individual subsections within vertex buffers. 
    // A subsection has a uniform bone and material index.
    TArray<FGeometryCollectionMeshElement> SubSections;
 
    void Serialize(FArchive& Ar);
};
 
class FGeometryCollectionRenderData
{
public:
    FGeometryCollectionRenderData() = default;
    ~FGeometryCollectionRenderData();
 
#if WITH_EDITOR
    struct FCreateDesc
    {
        bool bEnableNanite = false;
        bool bEnableNaniteFallback = false;
        bool bUseFullPrecisionUVs = false;
        bool bConvertVertexColorsToSRGB = false;
        uint32 NaniteMinimumResidencyInKB = 0;
    };
 
    static TUniquePtr<FGeometryCollectionRenderData> Create(FGeometryCollection& InCollection, FCreateDesc const& InDesc);
#endif
 
    bool IsInitialized()
    {
        return bIsInitialized;
    }
 
    void Serialize(FArchive& Ar, UGeometryCollection& Owner);
 
    void InitResources(UGeometryCollection const& Owner);
 
    void ReleaseResources();
 
    bool bHasMeshData = false;
    bool bHasNaniteData = false;
 
    FGeometryCollectionMeshResources MeshResource;
 
    FGeometryCollectionMeshDescription MeshDescription;
 
    TPimplPtr<Nanite::FResources> NaniteResourcesPtr;
 
    FBoxSphereBounds PreSkinnedBounds = FBoxSphereBounds(ForceInitToZero);
 
private:
    bool bIsInitialized = false;
};