- from [Oskar Kogut](https://github.com/kretoskar): if you change a `BlueprintCallable` function to `const` (or otherwise make it pure), the editor will automatically correct the `Exec` pin flow for you
+ the design of Blueprint the Language is pretty dated - it is still an imperative language and has a concept similar to statements (`Exec` pins), which breaks the entire idea of pure data
flow and introduces control flow into the mix
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- this split is called _pure_ and _impure_ nodes, where impure nodes are those that perform control flow (ie. those with `Exec` pins)
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+ this results in weird edge cases like needing two separate node types to handle branching (one that can have side effects - `Branch`, and another that can't - `Select`)
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- `Branch` is used to shuttle control flow between two `Exec` lines, based on a `Bool`. you get a `True` branch and a `False` branch
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+ and `Select` is used to choose a value based on another value, kind of like a ternary in C++
- however it is quite annoying because you can only switch on enums (and other stuff that has a finite set of values), whereas with `Branch` you can use any `Bool` condition you want
+ this would be fine if not for the existence of Gameplay Tags, which precisely _do not_ have a finite set of values
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- there is a `Switch on Gameplay Tag` node, but that is for control flow and not data flow!
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- this isn't an unsolvable problem but it illustrates the pure vs impure issue pretty well - you'd have to duplicate the implementation of `Switch on Gameplay Tag` to have
a version without an `Exec` pin
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+ I'm seeing a bit of a semblance to the classic [function coloring problem][def:article/function_coloring]
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+ except where it usually applies to the `async` concept found in most modern programming languages, here it applies to the concept of control flow vs data flow
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- and speaking of `async`, [Blueprint handles the classic `async` problem very gracefully][branch:01H8Y0CKD106HXQAJK87XV0H93]!
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+ despite its flaws, one of Blueprint's strengths is asynchronous and latent tasks
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- since control flow is based on those `Exec` pins, you can easily map your classic concept of callbacks to simply firing off the appropriate `Exec` pin
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- for example the node for playing animations (`Play AnimMontage`) has a few pins coming out of it that signal playback events like `On Ended`, `On Blend Out`, `On Interrupted`
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- and you wouldn't even know these are implemented as delegates in C++landia. it just feels like a first-class feature
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- the only gripe I have is that you can only have latent nodes in the main event graph (you cannot have them within functions)
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- which is annoying but not terrible, since most of that latent, high level gameplay logic happens inside the main event graph anyways
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+ the editor UI, despite [being helpful as it is][branch:01H8Y0CKD1G06CG62XWZ02JREC], is far from perfect
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- it's actually quite janky and there tend to be brief flashes of content falling into place
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- this is true of other parts of the Unreal editor UI but I'll focus on Blueprint here
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+ node UIs are laid out lazily, by default using an algorithm that does not produce precise results for pin locations
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- which means that when you first load a Blueprint, some of the wires will be bent in weird ways, and will fall into place as you zoom out and explore the graph more
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- the effect looks quite janky and really upsets my inner perfectionist
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+ as you zoom out, the nodes start looking just a little bit different due to font sizes being snapped to integers
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- at very low zoom levels, nodes stop rendering their text altogether, which makes their layout shift even more.
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- the effect of this is that nodes themselves take up less space, and it appears as though there is more space between them than there actually is
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- which can make it frustrating to lay nodes out on a large scale, because you'll only find out your nodes are overlapping when you zoom in real close
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- there's a `Straighten Connection` feature, which you can use to make your graphs look more aesthetically pleasing, but it only straightens the nodes such that they look good on the current zoom level
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- so what'll happen with it sometimes is you'll straighten a connection, then zoom in, and the connection won't be quite straight because of the aforementioned layout shift
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+ maintaining Blueprints in a large project could be a lot better
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+ with regards to your graphs becoming really large
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- everybody kinda sorta just formats nodes however they see fit, and there is no unified autoformatter
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- there's a reason people say Go's tooling is frickin' amazing, you know. it keeps codebases consistent!
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+ this results in what we Hat in Time modders used to call _Kismetti_ in the Unreal Engine 3 days but nowadays we'd call _Blueprintti_
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+ which is a portmanteau of Blueprint and spaghetti.
- there are plugins on the marketplace that solve this, but I refuse to believe Epic Games doesn't have this problem themselves
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- I'd guess it's just not very high up their priorities
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- refactoring your nodes is a hell of a pain. Blueprint is kind of write-only
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- say you're calling `ApplyGameplayEffectToTarget` a bunch of times and you want to replace those occurrences with a custom function that wraps `ApplyGameplayEffectToTarget`
with some extra semantic information, to make it more discoverable, searchable, and easy to use
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- well then good luck :hueh:
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- in a text-based language you could use a dumb search and replace to accomplish this task, but there is no such thing in Blueprint. :cry:
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+ with regards to assets (how long this darn stuff takes to load)
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- the biggest offender here being that hard references are the default
- thus you can add a Mesh Component to your Blueprint and it'll load _the entire mesh with all the textures and skeleton and everything_ when you wanna tweak a variable or some logic in the event graph
- and not asynchronously in the background, you will have to _wait_ for it to finish loading. which is pretty annoying
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+ the runtime performance isn't the best for a few reasons
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- the VM isn't implemented in the most optimal way
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- I've analyzed this in my [`dispatchers` repository][def:dispatchers/repo] if you wanna have a read
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- and that hard reference thing can make gameplay stutter when you're loading in new assets, but that's a more widespread issue than just with Blueprints
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- but in reality most of the logic you're implementing in Blueprints (high-level gameplay stuff) shouldn't be that performance sensitive
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- and it's not hard to extract the performance sensitive parts to C++ because Blueprint offers tools for refactoring your code
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- but all that doesn't prevent me from liking it!
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- since it's way more pleasant to write game logic in than C++, given that you don't need to wait a minute for your code to recompile.
