Trello: So there will be no PreFabs / BluFabs? :(

As most blueprint users know, it is currently not possible to compose Blueprints. You can only attach child actors and configure them with code manually. This makes many thanks very complicated and error prone.

“BlueFabs” should originally change that. Because of that, the “BluFabs” trello card was one of the most-wanted and highest-ratest features of the whole roadmap.

I Just noted that today, the was removed (“backburnered”):

Not long ago the predecessor card “PreFab” had several hundreds votes (but was also removed which reset the vote count to 0).


So does does this mean, Blueprints will still not be composable in the future (4.10/4.11)?


Why the heck would you need this? You can put blueprints within blueprints already. It’s a prefab in itself.

No, you can’t. You can only attach child actors and set their class to another blueprint. But this way, you can’t configure the child blueprint as you could do in the level editor (change it’s class defaults). The settings are simply not shown at edit time.

You will have to do that per code manually. You also can’t use blueprint-scripts/-components for that, because they can’t react to input events and it’s not possible to add components to them.

A small example: Think about an animated, configureable text, let’s call it ‘BP_textHint’. You can change it’s color, text and animation speed via public variables in the editor. But currently, you can’t use it as component in another Blueprint. You have to use a child actor and then you have to configure every instance of it in the parent’s construction script by hand. You can’t also directly reference it. Instead you will have to reference the child actor, read it’s value and cast it manually to the desired class type each time.

In other words: You currently need C++ to define custom components which you can add to blueprints.

Or you can do the smart thing and store a pointer to the actual blueprint child, which lets you access everything without having to cast it.

I get where you’re going, and I assume you were a Unity dev once. So you know the value of a prefab, but my own views say that it’s not a feature that should be high up there in terms of priority for UE4.
That’s just my view mate :slight_smile: Not shooting down your idea, I just can’t see an immediate use as I’ve not been limited in what I can do with Blueprints.

I think its very valuable personally. However, i would be happy to compromise with just having a much better blueprint view port editor.
Attaching actors to actors is totally viable and you can store a reference to them no problem, but being able to do that in the viewport would be amazing.

Im sad the see this feature get knocked off the road map :frowning: but that’s how things go.

I agree. The way blueprints behave - They’re actually prefabs.
If Epic went and made it so you could edit a child actor’s properties IN the viewport, that would be more than adequate.

I might pull down the source code and see if I can make a pull request for it.

No, you can not… :frowning:

Or did I miss something here:
Or here:

So, unfortunatley, BPs are far from being a “prefab” system. Still too many limitations when it comes to the construction script…
Or how would you solve these ones? :confused:

Im kind of speechless, seeing that feature gone :eek:

By the way… What means “backburnered”? Is that a real terminus technicus? (Like Sanskrit for “redneck” :rolleyes: )

Just means they aren’t considering it a priority. It’s still a planned feature, but it’s low priority, so it’s “put on the backburner”.

Yes, this would lead to an enormous productivity boost for composing blueprints. Ideally it should be possible to add them directly as components (like a point light, for example) so you don’t have to ‘extract’ the actual child blueprint from the child actor at runtime first, cast it and then creating an additional reference to it.

You should be able to convert actors from the scene into components:


Secondly, you should be able to add your actor blueprints (along with their own components etc.) as normal components in other blueprints and preconfigure them.

  • Amen! :smiley:

Yes, I once thought this is basically the whole point of Blueprint and code re-use?