Unresolved external symbol for UKismetMathLibrary::FindLookAtRotation

Development Programming & Scripting
1

When I try to use FindLookAtRotation like this

#include "Kismet/KismetMathLibrary.h"

FRotator new_rot = UKismetMathLibrary::FindLookAtRotation(location, this->GetTransform().GetLocation());


1>MyProject3Character.cpp.obj : error LNK2019: unresolved external symbol "public: static class FRotator __cdecl UKismetMathLibrary::FindLookAtRotation(class FVector const &,class FVector const &)" (?FindLookAtRotation@UKismetMathLibrary@@SA?AVFRotator@@AEBVFVector@@0@Z) referenced in function "protected: void __cdecl AMyProject3Character::SelectActorWithMouse(void)" (?SelectActorWithMouse@AMyProject3Character@@IEAAXXZ)
1>E:\UnrealProjects\ThirdPersonProject\Binaries\Win64\UE4Editor-MyProject3.dll : fatal error LNK1120: 1 unresolved external

How would I fix such an error?

2

The kismet math library isn’t set up to be usable from outside the Engine module, so that’s why you get the linker error. You have two options:

  1. Just call the C++ code directly. In this case that function is a very trivial wrapper so I would just do that.
  2. Locally change KismetMathLibrary to be accessible outside of Engine. You would do this by Adding ENGINE_API to the front of the class definition and removing MinimalAPI. Look at GameplayStatics as an example of how to do this.
3

So I read this because I was having the same issue and was a little confused as to what code to call. To achieve what you’re looking for it should look like this:

FRotationMatrix::MakeFromX(targetPawn->GetActorLocation() - lookingPawn->GetActorLocation()).Rotator();

4

thank you… simple and elegant.