Understanding the Blueprint Function Library

December 23, 2015
Οrfeas
Core How Tos, Unreal Engine 4 C++ Tutorials
8 Comments

Sometimes, we want to create functions which are going to do useful stuff and we don’t care which blueprints can call them. We want these functions to be included in every blueprint in our project. Unreal Engine provides a very easy way to create such functions. Let’s see how we can create them!

Creating such functions

I created a class named MyHelperFunctions which inherits from Blueprint Function Library Class. After the load is complete, you will notice that this class does not contain any default logic or declarations. Instead, the header file contains only the default GENERATED_BODY() macro as seen below:

bfl_h1

Right after the GENERATED_BODY() macro I type in the declaration of my function like the following image suggests:

bfl_h2

After that, I switch to the corresponding source file and type in the following functionality:

bfl_s1

Once you compile your code and switch to any blueprint graph you will notice that if you search the “UsefulFunction” you can call it without doing anything else.

Οrfeas

This Post Has 8 Comments

Diego says:

March 29, 2016 at 6:28 pm

Hi.! Thanks for the tutorials, are so cool. i have a question in this point.
When i call the funcion “UsefulFuncion”, got an error: This s not a MyHelperFuncions, therefore ‘Target’ must have a connection.
What should be connected?

Reply
1. orfeas says:
  
  March 29, 2016 at 8:11 pm
  
  Hello, does this appear on your Blueprint Editor? If so, can you provide a screenshot of your error?
  -Orfeas
  
  Reply
  1. Diego says:
    
    April 7, 2016 at 5:40 am
    
    http://i64.tinypic.com/15ds6x4.png
    
    i review and not sure whats wrong 🙁
    
    Reply
  2. Diego says:
    
    April 7, 2016 at 7:29 am
    
    I found the mistake, I miss the “public” within the BODY GENERATED () jeje
    
    Reply
    1. Οrfeas says:
      
      April 7, 2016 at 9:31 am
      
      I’m glad you fixed it!
      -Orfeas
      
      Reply
    2. Veii says:
      
      October 14, 2022 at 2:32 am
      
      It must be a public static function
      
      Reply
Chenglin Wang says:

February 8, 2017 at 2:22 pm

Hi Orfeas,

Thanks for the tutorial! One thing I notice when I try to follow your tutorial is that you have to declare your functions as static, otherwise the editor would complain that “This s not a MyHelperFuncions, therefore ‘self’ must have a connection”.

btw, I’m using 4.14 now.

Thanks,

Chenglin

Reply
1. Luiz Henrique Zanetti says:
  
  July 9, 2018 at 9:36 pm
  
  Write “static ” before the “void” word, for me works.
  
  Reply