UTexture2DArray Runtime 下添加图片

// Copyright 2022 Dexter.Wan. All Rights Reserved. 
// EMail: 45141961@qq.com
#include "Texture2DArrayWrapper.h"
#include "Engine/Texture2D.h"
#include "Engine/Texture2DArray.h"
PRAGMA_DISABLE_OPTIMIZATION
UTexture2DArrayWrapper::UTexture2DArrayWrapper(const FObjectInitializer& ObjectInitializer)
{
    Texture2DArray = CreateDefaultSubobject<UTexture2DArray>(TEXT("Texture2DArray"));
    Texture2DArray->UpdateResource();
}
UTexture2DArray* UTexture2DArrayWrapper::GetTextureArray() const
{
    return Texture2DArray;
}
void UTexture2DArrayWrapper::UpdateTextureArray(int32 TemplateIndex)
{
    // 重置有效纹理表列
    Textures.Reset();
    // 获取纹理数组的平台数据
    FTexturePlatformData*& PlatformData = *Texture2DArray->GetRunningPlatformData();
    // 如果纹理源为空 删除平台数据并更新渲染资源
    if (SourceTextures.Num() == 0)
    {
        if (PlatformData != nullptr)
        {
            delete PlatformData;
            PlatformData = nullptr;
        }
        Texture2DArray->UpdateResource();
        return;
    }
    // 如果模板索引无效 默认使用第0个纹理做模板
    TemplateIndex = SourceTextures.IsValidIndex(TemplateIndex) ? TemplateIndex : 0;
    // 获取模板纹理
    UTexture2D* TemplateTexture = SourceTextures[TemplateIndex];
    // 得到模板纹理的平台数据
    const FTexturePlatformData* TemplatePlatformData = *((UTexture*)TemplateTexture)->GetRunningPlatformData();
    // 取得模板纹理的长宽
    const int64 SizeX = TemplatePlatformData->SizeX;
    const int64 SizeY = TemplatePlatformData->SizeY;
    // 取得模板纹理的像素格式
    const EPixelFormat PixelFormat = TemplatePlatformData->PixelFormat;
    // 筛选有效的纹理
    for (UTexture2D* Texture : SourceTextures)
    {
        const FTexturePlatformData* SourcePlatformData = *((UTexture*)Texture)->GetRunningPlatformData();
        bool bIsInvalid = false;
        // 只有长宽与纹理格式都符号模板才有效
        bIsInvalid |= SourcePlatformData->SizeX != SizeX;
        bIsInvalid |= SourcePlatformData->SizeY != SizeY;
        bIsInvalid |= SourcePlatformData->PixelFormat != PixelFormat;
        if (!bIsInvalid)
        {
            Textures.AddUnique(Texture);
        }
    }
    // 获取纹理数组元素数与Mip层数
    const int64 NumSlices = Textures.Num();
    const int64 NumMips = TemplatePlatformData->Mips.Num();
    // 设置一般属性
    Texture2DArray->AddressX = TemplateTexture->AddressX;
    Texture2DArray->AddressY = TemplateTexture->AddressY;
    Texture2DArray->AddressZ = TextureAddress::TA_Wrap;
    Texture2DArray->SRGB = TemplateTexture->SRGB;
    Texture2DArray->Filter = TemplateTexture->Filter;
    Texture2DArray->MipLoadOptions = TemplateTexture->MipLoadOptions;
    // 如果平台数据不存在则创建
    if (PlatformData == nullptr)
    {
        PlatformData = new FTexturePlatformData();
    }
    // 设置纹理长宽元素数与像素格式
    PlatformData->SizeX = SizeX;
    PlatformData->SizeY = SizeY;
    PlatformData->PackedData = NumSlices;
    PlatformData->PixelFormat = PixelFormat;
    // 删除多余的Mip层
    if (PlatformData->Mips.Num() > NumMips)
    {
        PlatformData->Mips.RemoveAt(NumMips, PlatformData->Mips.Num() - NumMips);
    }
    // 遍历每个Mip层
    for (int32 MipIndex = 0; MipIndex < NumMips; ++MipIndex)
    {
        // 获取模板上对应的Mip层
        const FTexture2DMipMap& TemplateMip = TemplatePlatformData->Mips[MipIndex];
        // 获取此Mip层的元素字节数与总字节数
        const int64 ElementBytesCount = TemplateMip.BulkData.GetElementCount();
        const int64 MipBytesCount = ElementBytesCount * NumSlices;
        // 确保当前Mip层对象存在
        if (!PlatformData->Mips.IsValidIndex(MipIndex))
        {
            check(PlatformData->Mips.Num() == MipIndex);
            PlatformData->Mips.Add(new FTexture2DMipMap());
        }
        // 取得纹理数组中的Mip层对象
        FTexture2DMipMap& Mip = PlatformData->Mips[MipIndex];
        // 设置当前Mip层长宽及元素数
        Mip.SizeX = TemplateMip.SizeX;
        Mip.SizeY = TemplateMip.SizeY;
        Mip.SizeZ = NumSlices;
        // 以读写方式锁定当前Mip层
        Mip.BulkData.Lock(LOCK_READ_WRITE);
        // 重置Mip层到所需大小
        void* BulkData = (uint8*)Mip.BulkData.Realloc(MipBytesCount);
        // 遍历每个纹理元素
        for (int32 SliceIndex = 0; SliceIndex < NumSlices; ++SliceIndex)
        {
            // 获取源纹理平台数据
            FTexturePlatformData*& SourcePlatformData = *((UTexture*)Textures[SliceIndex])->GetRunningPlatformData();
            // 获取源纹理对应Mip层
            FTexture2DMipMap& SourceMip = SourcePlatformData->Mips[MipIndex];
            // 以只读方式锁定源纹理Mip层
            const void* SourceBulkData = SourceMip.BulkData.Lock(LOCK_READ_ONLY);
            // 从源纹理复制数据到纹理数组中
            FMemory::Memcpy((uint8*)BulkData + ElementBytesCount * SliceIndex, SourceBulkData, ElementBytesCount);
            // 解锁源纹理Mip层
            SourceMip.BulkData.Unlock();
        }
        // 解锁当前Mip层
        Mip.BulkData.Unlock();
    }
    // 更新纹理数组渲染资源
    Texture2DArray->UpdateResource();
}
const TArray<UTexture2D*>& UTexture2DArrayWrapper::GetTextures() const
{
    return Textures;
}
PRAGMA_ENABLE_OPTIMIZATION