Passing a variable from a level blueprint to another blueprint?

Development Programming & Scripting Blueprint
1

Hello all, here is a snip where I create an instance of a UObject-derived class that I wrote and call its Init method, then store a reference to it in a variable. This is done in my level blueprint.

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I would like to pass this reference to another blueprint so that it can access its data. My question is, how do I share this reference with another blueprint? From what I’ve seen, directly communicating between blueprints requires being able to make a variable of the same type as the target, which I haven’t found out how to do for a level blueprint. Will I have to move this functionality outside of the level blueprint?

2

There are two questions here:

  1. How does the Level Blueprint find your other blueprint instance or instances?

  2. How does the Level Blueprint actually communicate the value to that instance?

To solve #1, you typically use “find all actors of class,” or use tags on objects.

Once you have one or more instances from #1, you either make sure that your type has a known method or variable of the appropriate type, or you implement a specific interface that’s used to communicate with the object, get that interface from the object, and call the interface.

3

I should also mention that I’m trying to communicate data from the level blueprint to my UMG UI, so no actors.

I’m now having issues with implementing a C++ interface function in blueprints.
I created a C++ interface that I added to my level blueprint. This interface has a function that is defined as follows:



public:
	UFUNCTION(BlueprintCallable, BlueprintImplementableEvent, Category = "Getters")
	UPopulator* GetPopulator();

This function shows up in my left-hand list of functions as callable, but it does not allow me to override it in order to actually implement it.

My hope is that I would be able to override it and pass in my level blueprint’s instance of UPopulator. Then, I would be able to add the same interface to my UI blueprint and call the data that I need from the level blueprint. Am I approaching this wrong, or am I just overlooking something?

4

This sounds like a question about the specifics of the C++ / Blueprint calling interface (which goes through the Unreal header generation tool.)
When I look in the source code, I see lots of things that use BlueprintImplementableEvent, but those are NOT marked BlueprintCallable, so perhaps you should remove BlueprintCallable from your markup?