Comment by AussieWog93 | Hacker News Reader

Comment by AussieWog93 | Hacker News Reader

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I've heard that argument before, yet for almost all apps I've used in real life the opposite is true.

Game UIs are (from what I understand) written almost exclusively ImGui-style, with every single widget being fed updated state data every single frame as part of the game loop.

Yet, for whatever reason, even crazy-complex UIs like SupCom's seem to have no issue rendering in realtime with an entire 3D game running in the background, while simply resizing the window I'm typing into right now (a single textedit on a static HTML page) creates visible lag and chews up full CPU on a 2015 Macbook.

That's not to say retained-mode GUIs can't be performant (embedded systems rely on retained-mode to have reasonable performance), but on a modern system it seems like the loss in performance caused by inefficiently synchronising state in retained-mode GUIs is several orders of magnitude higher than the losses caused by pushing a couple of hundred textures every frame in an ImGui context.

The thing is those are likely to be simple GUIs. Those are a great use case for immediate mode. But try it with something that has a lot of:

- Wrapping text labels

- Widgets that are similar to CSS flexbox where the size of elements depends on other elements

- List/tree widgets or text editor widgets with large datasets in them

And then you will notice performance tanks. Think of trying to build a text editor that way, if you opened a 5MB text file, you would have to rescan the whole 5MB and compute reflow for it every time.

Game UIs do not generally involve user interaction based on the position of a pointer within the 2D screen geometry. They generally have a very limited event/input system that only takes effect via an overlay. Objects do not come and go from the "model" as a matter of course. They certainly do a LOT of drawing, and they do it very fast, but the challenges of UI design (particularly toolkit design) don't really reside in "how do we draw this stuff really fast".

I do often reflect on how fast game UIs draw, and compare that to the headaches we have in the UI of a digital audio workstation. It generally seems almost inconceivable how we could be so slow in comparison. But then I think about all the ways the user has to interact with the actual UI (not the backend data model), and it starts to seem like a different sort of programming model entirely.

I play games very infrequently, but my anecdata is the opposite: games usually have laggy UI with an inconsistent reaction to input events, noticeable latency, frequent breakage and generally worse user experience (and of course mostly without the ability to resize anything, to compare with browser), even when compared to browsers and Electron apps.

And would you want your laptop taking as much power writing a word document as it takes to run a AAA game?

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