CODEWITHSUNDEEP
unreal-engine4unreal-blueprint
Chris Javier Oliveros
Chris Javier Oliveros

Reputation: 227

Are UE4 Blueprints the same with a C++ class? If so, how will I implement a class design?

Good day! I am new to using Unreal Engine 4 and I have a few questions about how exactly blueprints work. From my understanding of it, every blueprint works like a class. By that I mean one blueprint is much like one class in an OOP programming language.

Please educate me as to - if my assumption is correct or wrong. If wrong, then maybe you could help me achieve what I want in a different method/perspective. I am willing to learn and accept suggestions.

If at some point my understanding is correct - that blueprints are actually individual classes - I would really appreciate it if you could (please) guide as to where to go and how to implement a design that I want to create. This is from a programmers perspective (PHP OOP Programming). Forgive the approach, I'm just using PHP to logically express how I want the class to work. Plus, it is the only OOP programming I know atm.

  1. I want to create a class named: Items. class Item {}

  2. This class is going to handle everything item related, thus we will have to give it a lot of properties/variable. (Below is just an example; Again I'm using PHP as an example.)

    class Item {

        var $id;
    var $name;
    var $description;
    var $type;
    var $subType;
    var $mesh;
    var $materials;

    }

3.) I would like to initiate this class by having two variables as its construct arguments. (We will require itemID and itemType). This is because I will use these two variables to retrieve the item's data which is already available in a data table. I will use those data in the table to populate the class properties/variables. (I'm not sure if I said that right. I hope you understood my point anyway.)

   class Item {

        var $id;
        var $name;
        var $description;
        var $type;
        var $subType;
        var $mesh;
        var $materials; 

        function _construct($cons_itemID, $cons_itemType) {

               /*-- Start getting the item Data here based on what item and type provided. Then, push that data into the class properties/variables. We will use individual methods/functions to fill other properties/variables later. --*/

        }
}

4.) Basically with that design I could easily pass on an item ID to the class and then get the item's name, description, mesh, materials and etc using pointers.

Example: 

$weapon = new Item('10001','Weapon');
$weaponMesh = $weapon->getMesh();

$armor = new Item('12345','Armor');
$armorName = $armor->getName();

I'm just having a lot of trouble working with blueprint and achieve this method or even something similar to it. I'm not trying to avoid C++, I would love to learn it but I just don't have the time freedom right now.

Few things I have tried to make it work:

For all those who will help or answer. Thank you!

~ Chris

Upvotes: 3

Views: 2026

Answers (1)

Pavel Pája Halbich
Pavel Pája Halbich

Reputation: 1583

So far as I know, yes, we can assume that each blueprint can be viewed as class. (Moreover, since UE 4.12 (in UE 4.11 that functionality is marked as experimental I think) you can check Compile blueprints under Project settings -> Packaging. That will create native class for each blueprint.)

You can create either Blueprint or C++ class based on Object (UObject in C++). Then you can specify all properties (or variables in UE editor terminology). In BP you have small advantage: you can mark some properties as Visible at spawn (they must be Public and Visible). So when you are creating new instance of that class, you can explicitly pass values to that properties. And in BP Construct event, that properties are correctly filled, thus you can set another properties values based on given ID and Type.

In C++ class having different arguments than FObjectInitializer is not possible, thus you don't have that values in time when constructor is executed. But it is not so hard to achieve same functionality, you can find example here: https://answers.unrealengine.com/questions/156055/passing-arguments-to-constructors-in-ue4.html.

Something about list of what you had tried:

  • Spawn actor - derive from actor only if you intend to have that BP in scene. Actors are subjects to game updates and rendering, so having actor only as data container is very wrong.
  • BP Macro is same as BP Function except function will be called just like function (so executing necesary actions by function call conventions) and macro will replace it's implementation in place, where you are calling that macro. More exhausting explanation here.
  • If I would implement your code, I'd do it like I said and then I'll have that class as property in some component and that component would be attached to some actor, which would be placed in scene.

Upvotes: 3

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