Reading in a configuration File.

• A reference
• I was unhappy last time that I had to create the list of destinations by hand.
• I would really like to put these in a file and load the file.
• Fortunately this requires us to drop down to c++
• I am going to step through creating a C++ Blueprint Function Library class.
  • These are "tools"
  • Loading a file makes sense at this level.
  • And I don't find any way to do it at the blueprint level.
• This is perhaps not the best implementation.
  • If we were masters, we would return an array of structs.
  • But we just got the blueprint level struct.
  • So I am going to return an array of strings.
• Start by creating a new C++ class
  • File, New C++ Class
  • 
  • Select Blueprint Function Library as your parent class.
  • 
  • Give it a name, I selected TransporterFunctions
  • 
  • This will create some files and compile.
  • On content in the Content Browser a new file will show up.
    • C++ Classes
    • With a folder for the project.
    • 
    • I have some extra things here, working through notes.
    • Transporter Functions
    • Double clicking on this should start visual studios
• What we have
  • TrnsporterFunctions.h

  • // Fill out your copyright notice in the Description page of Project Settings.
    
    #pragma once
    
    #include "CoreMinimal.h"
    #include "Kismet/BlueprintFunctionLibrary.h"
    #include "TransporterFunctions.generated.h"
    
    UCLASS()
    class FEB9FINAL_API UTransporterFunctions : public UBlueprintFunctionLibrary
    {
    	GENERATED_BODY()
    
    }; 

  • #pragma once acts as the guards.
  • UCLASS() I believe is a macro (see here) which allows the code to "examine" it's self.
    • "Unreal has its own system to harvest, query, and manipulate information about C++ classes, structs, functions, member variables, and enumerations. "
    • Just let it alone, along with all other U* references.
  • It includes a number of libraries.
  • TransporterFunctions.cpp

    // Fill out your copyright notice in the Description page of Project Settings.
    
    
    #include "TransporterFunctions.h"
              

• Implementing a function
  • Let's add a simple "HelloWorld" function
  • It will take an int and repeat hello world that many times.
  • First add a function prototype in the .h file.
    • We need to tell unreal about it, so add the following lines

    • class FEB9FINAL_API UTransporterFunctions : public UBlueprintFunctionLibrary
      {
      	GENERATED_BODY()
      
      		UFUNCTION(BlueprintCallable, Category = "TransporterFuns")
      		static FString HelloWorld(int count);
                     

  • Then add the function to the source code file
    • You can click on the function name and select Quick Actions and Refactoring
    • 
    • And select Create definition of 'HelloWorld' ...
    • 

    • FString UTransporterFunctions::HelloWorld(int count)
      {
      	FString rv;
      	int i;
      
      	for (i = 0; i < count; i++) {
      		rv += TEXT("Hello World\n");
      	}
      
      	return rv;
      }
                     

    • FString is the Unreal string type.
    • reference
    • TEXT is a macro that converts all kinds of things to an FString.
  • Save this.
  • But compile it in the Unreal Engine.
    • If you compile in visual studios you seem to run into problems.
  • If all is good, you should be able to call "Hello World" at the blueprint level.
  • 
  • A better function
    • Took the basic for this from here
  • I want to read the data from a file and store it into an array of strings
    • One line per string.
  • I want an array of results
    • A TArray is like the c++ vector class.
    • Fast, memory efficient, safe
    • They claim it is the one to use.
  • I think the T is for template.
  • I added the following to the header file

    • UCLASS()
      class FEB9FINAL_API UTransporterFunctions : public UBlueprintFunctionLibrary
      {
      	GENERATED_BODY()
      	
      		UFUNCTION(BlueprintCallable, Category = "TransporterFuns")
      		static FString HelloWorld(int count);
      	
         	        UFUNCTION(BlueprintCallable, Category = "TransporterFuns")
      		static TArray<FString> ReadPlaceFile(FString filename, bool& success);
      };
                   

    • I generated the header and added the following to the C++ file

      TArray<FString> UTransporterFunctions::ReadPlaceFile(FString filename, bool& success)
      {
      
      	success = false;
      
      	FString directory = FPaths::Combine(FPaths::ProjectContentDir(), TEXT("MyData"));
      	TArray<FString> result;
      
      	IPlatformFile& file = FPlatformFileManager::Get().GetPlatformFile();
      	if (file.CreateDirectory(*directory)) {
      		FString myFile = directory + "/" + filename;
      		success = FFileHelper::LoadFileToStringArray(result, *myFile);
      	}
      
      	return result; 
      }

  • Compiled and tested the results.
  • I placed a directory called MyData in the Components directory of the project.
  • I placed a file places.txt in this directory.
  • 
  • 
  •