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Confusion about path argument in FObjectFinder

Development Discussion C++ Gameplay Programming
#1

I’m trying to give my character class a skeletal mesh but am unclear how FObjectFinder works. I have 2 questions.

  1. What should the path argument be, and what is it relative to?
    For instance -


// Absolute path to asset file 
E:/Unreal/Projects/FPSProject/Content/Models/SK_Mannequin.uasset

// Absolute path to class .cpp source file 
E:/Unreal/Projects/FPSProject/Source/FPSProject/FPSCharacter.cpp

If I make this call from FPSCharacter.cpp …


static ConstructorHelpers::FObjectFinder<USkeletalMesh> 
        NewMesh(TEXT("/FPSProject/Content/Models/SK_Mannequin.uasset"));

… Will the directory “/FPSProject” be evaluated as



E:/Unreal/Projects/FPSProject/Source/FPSProject/

or 

E:/Unreal/Projects/FPSProject/
  1. What is the prefix of the path in FObjectFinder’s argument?
    In the following code, the argument is “StaticMesh’/Game/StarterContent/Props/MaterialSphere.MaterialSphere’”
    What is “StaticMesh” in that argument?


static ConstructorHelpers::FObjectFinder<UStaticMesh>
BaseMeshAsset(TEXT("StaticMesh'/Game/StarterContent/Props/MaterialSphere.MaterialSphere'"));

Is it a class type, a file name, a directory?
What happens if you exclude it?

I’ve been stuck on this for a while, so any help would be appreciated.
Also any examples and explanations of how to use FObjectFinder, and how it works, would be very helpful.

Thanks!

#2

The path is relative to your (or the engines, or a plugins) content folder. For example:
/Game/Folder/Asset.Asset will be /Project/Content/Folder/Asset.uasset on disk.
/Engine/Folder/Asset.Asset will be /Engine/Content/Folder/Asset.uasset on disk.
/PluginName/Folder/Asset.Asset will be something like /Engine/Plugins/PluginName/Content/Folder/Asset.uasset.

If you’re wondering about the Asset.Asset thing, that’s because you’re loading a uasset package called Asset and then the object that is also called Asset from that. Pretty much the only time you need to change this convention is when loading a blueprint, where you need Asset.Asset_C to get the generated class object.

The “prefix” lets you filter what type of object to load. It is more of a relict and not particularly useful, since you’re already filtering by class when loading things. I’d just leave it out.

Going back to your example, the path you want is “/Game/Models/SK_Mannequin.SK_Mannequin”

#3

All our code is like this:



const FString CROSSHAIR_TEXTURE = "/Game/Textures/Icons/CrossHairAimPoint.CrossHairAimPoint";
 _textureCrossHair = ConstructorHelpers::FObjectFinder<UTexture2D>(*CROSSHAIR_TEXTURE).Object;
#4

Has this practice changed? I’m using this method in 4.24 and am getting this error:


2>C:\Program Files\Epic Games\UE_4.24\Engine\Source\Runtime\CoreUObject\Public\UObject/ConstructorHelpers.h(110): error C2664: 'void ConstructorHelpers::ValidateObject(UObject *,const FString &,const TCHAR *)': cannot convert argument 1 from 'T *' to 'UObject *'
#5

I fixed similar error by including a corresponding header file, in this case a header for UTexture2D.