【UE4】 Texture2D 数据读写

创建texture

• 原文地址

• 方式一

      // https://www.cnblogs.com/shiroe/p/15438401.html
  void AActor_Assignment2::TextureFromImage_Internal( const TArray<FColor>& SrcData, const bool UseAlpha)
  {
  	const int32 SrcWidth = CanvasSize.X;
  	const int32 SrcHeight = CanvasSize.Y;
  	// Create the texture
  	T_Result = UTexture2D::CreateTransient(CanvasSize.X, CanvasSize.Y, PF_B8G8R8A8);
  
  	// Lock the texture so it can be modified
  	uint8* MipData = static_cast<uint8*>(T_Result->PlatformData->Mips[0].BulkData.Lock(LOCK_READ_WRITE));
  
  	// Create base mip.
  	uint8* DestPtr = NULL;
  	const FColor* SrcPtr = NULL;
  	for (int32 y = 0; y < SrcHeight; y++)
  	{
  		DestPtr = &MipData[(SrcHeight - 1 - y) * SrcWidth * sizeof(FColor)];
  		SrcPtr = const_cast<FColor*>(&SrcData[(SrcHeight - 1 - y) * SrcWidth]);
  		for (int32 x = 0; x < SrcWidth; x++)
  		{
  			*DestPtr++ = SrcPtr->B;
  			*DestPtr++ = SrcPtr->G;
  			*DestPtr++ = SrcPtr->R;
  			if (UseAlpha)
  			{
  				*DestPtr++ = SrcPtr->A;
  			}
  			else
  			{
  				*DestPtr++ = 0xFF;
  			}
  			SrcPtr++;
  		}
  	}
  
  	// Unlock the texture
  	T_Result->PlatformData->Mips[0].BulkData.Unlock();
  	T_Result->UpdateResource();
  
  }
  

• 方式二

      // https://www.cnblogs.com/shiroe/p/15438401.html
  void AHw7_Main::CreateTexture()
  {
  	T_Result = UTexture2D::CreateTransient(width, height);
  	FTexture2DMipMap& Mip = T_Result->PlatformData->Mips[0];
  	FColor* Data = (FColor*)Mip.BulkData.Lock(LOCK_READ_WRITE);
  	FMemory::Memzero(Data, width * height * sizeof(FColor));
  	Mip.BulkData.Unlock();
  	T_Result->UpdateResource();
  	return;
  	//T_Result->UpdateResource();
  }
  

• 方式三 UpdateTextureRegions这个函数貌似不适合创建，适合更新

  VideoTextureColor = UTexture2D::CreateTransient(640, 480, PF_B8G8R8A8);
  VideoTextureColor->UpdateResource();
  FUpdateTextureRegion2D* RegionColor = new FUpdateTextureRegion2D(0, 0, 0, 0, 640, 480);
  //FUpdateTextureRegionData* ColorRegionData = new FUpdateTextureRegionsData;
  
  // Populate the texture with blue color
  TArray<FColor> PixelDepthData;
  PixelDepthData.Init(FColor(255, 255, 0, 255), 640 * 480);
  
  
  VideoTextureColor->UpdateTextureRegions(
  	(int32)0,
  	(uint32)1,
  	RegionColor,
  	(uint32)(4 * 640),
  	(uint32)4,
  	(uint8*)PixelDepthData.GetData()
  );
  VideoTextureColor->LODGroup = TEXTUREGROUP_Pixels2D;
  

访问Texture数据

• 方式一

      // https://www.cnblogs.com/shiroe/p/15438401.html
  void AHw7_Main::UpdateTexture()
  {
  	// 更新texture
  	if (T_Result && !pixelQueue.IsEmpty())
  	{
  		FTexture2DMipMap& Mip = T_Result->PlatformData->Mips[0];
  		FColor* Data = (FColor*)Mip.BulkData.Lock(LOCK_READ_WRITE);
  
  		for (int i = 0; i < width * 2 && !pixelQueue.IsEmpty(); i++) {
  			ScreenPixel calc_res;
  			ensure(pixelQueue.Dequeue(calc_res));
  			if (calc_res.index < width * height)
  				Data[calc_res.index] = calc_res.color;
  		}
  		Mip.BulkData.Unlock();
  		T_Result->UpdateResource();
  
  	}
  }
  

• 方式二

      // https://www.cnblogs.com/shiroe/p/15438401.html
  VideoTextureColor->CompressionSettings = TextureCompressionSettings::TC_VectorDisplacementmap;
  VideoTextureColor->MipGenSettings = TextureMipGenSettings::TMGS_NoMipmaps;
  VideoTextureColor->SRGB = false;  //确保这些设置，否则颜色容易丢失
  //VideoTextureColor->LODGroup = TEXTUREGROUP_Pixels2D;
  VideoTextureColor->UpdateResource();
  
  FTexture2DMipMap& Mip = VideoTextureColor->PlatformData->Mips[0];
  uint8* Data = (uint8*)Mip.BulkData.Lock(LOCK_READ_ONLY);
  // read here in low level:
  //let's say I want pixel x = 300, y = 23
  //basic formula, data[channels * (width * y + x)];
  FColor pixelColor = FColor(0, 0, 0, 255);
  int x = 200, y = 2;
  pixelColor.B = Data[4 * (640 * y + x) + 0];
  pixelColor.G = Data[4 * (640 * y + x) + 1];
  pixelColor.R = Data[4 * (640 * y + x) + 2];
  pixelColor.A = 255;
  
  Mip.BulkData.Unlock();
  VideoTextureColor->UpdateResource();
  UKismetSystemLibrary::PrintString(GetWorld(), TEXT("font color"), true, true, pixelColor);
  

• 方式三
  About ENQUEUE_RENDER_COMMAND 渲染线程

访问材质上的点所对应贴图uv上的颜色