keywords: [UE4]UFunction-ProcessEvent返回值与输出参数获取

调用UFunction

执行UFuncion，使用 ProcessEvent ：

UFunction* Fun = Actor->FindFunction(TEXT("TestFun"));
if(Fun)
{
    Actor->ProcessEvent(Fun, Buffer);
}
查询UFunction信息

获取返回值：

UFunction* Fun = Actor->FindFunction(TEXT("TestFun"));
if(Fun)
{
    FFrame frame = FFrame(Actor, Fun, Buffer, NULL, Fun->Children);
    uint8* ReturnValueAdress = Buffer + Fun->ReturnValueOffset;
    int* intp = (int*)ReturnValueAdress; //hardcoded exemple for a int return
    Fun->Invoke(Actor, frame, intp);
}

获取输出参数：

if(UFunction* Fun = Actor->FindFunction(TEXT("TestFun")))
{
    if(uint8* Buffer = (uint8*)FMemory_Alloca(Fun->ParmsSize))
    {
        for (TFieldIterator<UProperty> PropIt(Fun, EFieldIteratorFlags::ExcludeSuper); PropIt; ++PropIt)
        {
            UProperty* Property = *PropIt;

            bool isOut = Property->HasAnyPropertyFlags(CPF_OutParm);
            if (!isOut)
            {
                continue;
            }

            uint8* outValueAddr = Property->ContainerPtrToValuePtr<uint8>(Buffer);
            float* floatp = (float*)outValueAddr;   //hardcoded example for float
        }
    }
}

通过 FindFunction 查找的函数必须添加 UFUNCTION() 宏，否则 FindFunction 返回NULL。

参考自：
https://answers.unrealengine.com/questions/516440/ufunction-invoke.html

对的那条路，往往不是最好走的。