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Comment by bestinterest | Hacker News Reader

I have the exact same feelings.

Is immediate mode GUI's just that much better? Instead of a complex React/Redux style setup, how much easier would state management be if we had a render loop like game dev? Does that even make sense?

I am very envious at the pure programming skills of so many game developers. UI's in indie games are just a side thing in the deep complexity of a game and they end up looking incredible compared to the level of effort required for year long web app projects.

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They've drifted away from calling it that, but the whole idea behind React was to bring immediate-mode rendering to the web. It has an event loop where each "frame" you render the current state from scratch, rather than explicitly updating the state of retained controls.

I use Zui with Kha/Haxe - an immediate mode GUI library. I cannot overstate how immediate mode GUI greatly simplifies ui development. React is massive step up from OOP/scenegraph/display list style gui, but it is still so complex and cumbersome compared to immediate mode. I can’t fathom why there is such little exploration in this space and it seems mostly limited to gamedev.

https://github.com/armory3d/zui

Immediate mode GUI makes perfect sense for applications that repaint themselves all the time 60 (or more) times per second, as they're already doing the work and there's little overhead added by handling such GUI. I can deal with 3D editor working this way, but I don't think I would be very happy if my e-mail client did.

I don’t have much understanding of the internals of the immediate mode renderers, but I think there are optimisations to only redraw regions where component inputs have changed.

You typically have to implement those optimizations yourself, and most people don’t. It’s outside the scope of the renderer in most cases for it to decide what should or should not be rendered. As a result, immediate mode GUI, while fast to develop, typically really kills a battery life on mobile.

That's just an implementation detail. The main benefits of an immediate mode UI is the API for using it. There's no reason that the loop has to run at 60 FPS. It could even be event-based, so it only updates when the user does something, for example.

Yes and no. That API makes certain approaches easier and other harder. Even if you manage to render only the changed parts of the screen, you still execute all your UI logic all the time so the renderer can be aware of what changed in the first place. Also, more involved stuff like animations become much more complex once you go event-based, to the point where retained mode UI may end up being a better choice from the API perspective. It all depends on what exactly you're implementing, and games often are a natural fit for immediate mode as they usually allow to keep it simple with no real downsides.

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