【UE4虛幻】UTexture2D纹理裁剪函数,g9x（ue4 虚拟纹理）

文件名：【UE4虛幻】UTexture2D纹理裁剪函数,g9x 【UE4虛幻】UTexture2D纹理裁剪函数

参数说明： 源2D纹理图片：UTexture2D* SourceTexture 裁剪区域的左上角：const FVector2D TopLeft 裁剪区域的右下角：const FVector2D BottomRight 返回值是裁剪之后的纹理图片

UTexture2D* APointProjection::CropPicture(UTexture2D* SourceTexture,const FVector2D TopLeft, const FVector2D BottomRight){if (!SourceTexture || !SourceTexture->IsValidLowLevel()){UE_LOG(LogTemp, Error, TEXT("value error"));return SourceTexture;}int32 TextureWidth = BottomRight.X - TopLeft.X;int32 TextureHeight = BottomRight.Y - TopLeft.Y;UE_LOG(LogTemp, Error, TEXT("TextureWidth is %d TextureHeight is %d"), TextureWidth, TextureHeight);const uint8* FormatedImageData = static_cast<const uint8*>(SourceTexture->PlatformData->Mips[0].BulkData.LockReadOnly());TUniquePtr<uint8[]> ClippedTextureData(new uint8[TextureWidth * TextureHeight * 4]);UE_LOG(LogTemp, Error, TEXT("FormatedImageData %p"), FormatedImageData);for (int32 y = TopLeft.Y; y < BottomRight.Y - 1; y++) //减去一是为了防止类型转换而导致越界{for (int32 x = TopLeft.X; x < BottomRight.X - 1; x++){int32 m_x = x - TopLeft.X;int32 m_y = y - TopLeft.Y;int32 curPixelIndex1 = (m_y * TextureWidth + m_x);int32 curPixelIndex2 = (y * SourceTexture->GetSizeX() + x);// 将当前像素颜色添加到像素数组中，注意 BGRA 通道的顺序ClippedTextureData[curPixelIndex1 * 4] = FormatedImageData[curPixelIndex2 * 4];ClippedTextureData[curPixelIndex1 * 4 + 1] = FormatedImageData[curPixelIndex2 * 4 + 1];ClippedTextureData[curPixelIndex1 * 4 + 2] = FormatedImageData[curPixelIndex2 * 4 + 2];ClippedTextureData[curPixelIndex1 * 4 + 3] = FormatedImageData[curPixelIndex2 * 4 + 3];}}// 解锁 MipMapSourceTexture->PlatformData->Mips[0].BulkData.Unlock();写操作UTexture2D* CropTexture = UTexture2D::CreateTransient(TextureWidth, TextureHeight, SourceTexture->GetPixelFormat());void* TextureData = CropTexture->PlatformData->Mips[0].BulkData.Lock(LOCK_READ_WRITE);FMemory::Memcpy(TextureData, ClippedTextureData.Get(), sizeof(uint8) * TextureHeight * TextureWidth * 4);CropTexture->PlatformData->Mips[0].BulkData.Unlock();CropTexture->UpdateResource();return CropTexture;}