欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页

UE4 C++ 从内存数据创建动态材质

程序员文章站 2022-06-11 07:53:22
...

动态材质的创建

需要注意的是,本文写的是根据二进制数据流创建动态材质,而不是单纯的用C++加载一个材质并赋予模型。项目有需求需要把视频采集卡采集到的视频在UE4里显示,所以简单研究了一下。

我的目的是把用第三方硬件的SDK开发出来的程序写的数据流创建为动态材质,所以如何把采集到的视频写成数据流不再考虑范围内,我们直接用就好了。

unsigned int CaptureChannels::readChannelData(unsigned int cardId, unsigned int channelId, unsigned char *buffer, unsigned int &length)
{
    unsigned int idx = cardId * MAX_CHANNEL_NUM_PER_CARD + channelId;
    memcpy(buffer, channelData[idx].buffer, channelData[idx].buflen);
    length = channelData[idx].buflen;
    return channelData[idx].seqNo;
}

所以,我们只要把数据从buffer从还原为图片在构建贴图就好了。

在UE4中新建一个Actor类,因为要往场景中放置,材质要在模型上显示。然后新建一个材质并把它的texture节点参数化再继承它的材质实例。
在头文件中声明变量

    UPROPERTY(EditAnywhere, Category = Mesh)
    class UStaticMeshComponent* MeshScreen;
    unsigned char *buffer;
    UTexture2D *m_texture;
    UMaterialInterface *ScreenMaterial;
    UMaterialInstanceDynamic *DynamicMaterial; 

在源文件中的构造函数和BeginPlay函数中完成初始化操作

ACaptureActor::ACaptureActor()
{
    // Set this actor to call Tick() every frame.  You can turn this off to improve performance if you don't need it.
    PrimaryActorTick.bCanEverTick = true;
    MeshScreen = CreateDefaultSubobject<UStaticMeshComponent>(TEXT("Mesh1P"));
    buffer = new unsigned char[2048 * 2048 * 4];

}

// Called when the game starts or when spawned
void ACaptureActor::BeginPlay()
{
    Super::BeginPlay();
    FString path = "/Game/Mesh/phong1.phong1";
    ScreenMaterial = Cast<UMaterialInterface>(StaticLoadObject(UMaterialInterface::StaticClass(), nullptr, *path));
    DynamicMaterial = UMaterialInstanceDynamic::Create(ScreenMaterial, this);
    CaptureChannels::Instance()->readConfig();
    CaptureChannels::Instance()->initCaputre();
    m_texture = UTexture2D::CreateTransient(1024, 512);

}

CaptureChannels的相关操作不用理会。然后编写核心函数并在Tick中调用。

void ACaptureActor::setTextureFromLoadImg(bool bWasSuccessful)
{
    unsigned int  len = 0;

    CaptureChannels::Instance()->run();
    CaptureChannels::Instance()->readChannelData(0, 0, buffer, len);

    //FUpdateTextureRegion2D *Region2D = new FUpdateTextureRegion2D(0, 0, 0, 0, 1024, 512);
    //m_texture->UpdateTextureRegions(0, 1, Region2D, 1, 4, buffer, test);

    void* temp_dataPtr = m_texture->PlatformData->Mips[0].BulkData.Lock(LOCK_READ_WRITE);
    FMemory::Memcpy(temp_dataPtr, buffer, len);
    m_texture->PlatformData->Mips[0].BulkData.Unlock();

    m_texture->UpdateResource();

    DynamicMaterial->SetTextureParameterValue("TextureScreen", m_texture);
    MeshScreen->SetMaterial(0, DynamicMaterial);

}

我注释掉的两行代码是UE4的API,从4.9到现在有了很大的改变,理论上是可以直接用的,我没有找到用法,知道的朋友请不吝赐教。大体思路是,先在UE4里创建材质和材质实例,然后在C++中修改参数。

相关标签: ue