Win2D VS FluentAvalonia

For Windows only, Win2D!

You're looking for Win2D: https://github.com/microsoft/Win2D. It's the official D2D WinRT wrapper, supports UWP and WinUI, has seamless interior with XAML, it's very easy to use and has extensive interop APIs (even more so once we ship the next release) that give you maximum control if needed. I recommend checking it out 🙂

Your easiest bet is likely to use Win2D within UWP or WinUI 3, then you could just throw a CanvasControl as the root of your UI and draw whatever you want on it, including setting individual pixels. Alternatively an easy way to do that could be to use a WriteableBitmap in WPF/UWP/WinUI 3 just drawn into a root Border or something, and then you can easily manipulate pixels there. Of course, that'd be slower and not CPU accelerated, but still viable depending on your exact use case.

Alternatively you can also try Win2D, which is an official wrapper for D2D available for UWP and WinUI. You could use its CanvasAnimatedControl panel and then do your drawing from there, and just manually draw all your particles. The actual drawing would still be GPU accelerated, so it'd be relatively efficient (though less than using a custom shader, as you'd be queueing each particle from the CPU side).

To make a long story short, it's a UWP app since I've used DirectX 11 for drawing on the screen. I use C#, and I needed win2d (https://github.com/microsoft/Win2D)

Universal Windows Platform was introduced as the new hotness, but in my personal experience lacks a number of features from WPF I couldn't part with. It seems to have flopped a bit outside of applications developed by Microsoft. Projects that I though would bring features I really wanted (like win2d: GitHub - microsoft/Win2D) seem to have lost support. I'd hold off on this.

This is what you need : https://github.com/amwx/FluentAvalonia

FluentAvalonia

If you want to have the FluentUI theme you can use https://github.com/amwx/FluentAvalonia. I used this for another project and didnt have any issues.

It's literally not the most basic control for Windows development. That would be something like Window, Button, or TextBlock. If you're only using the basic features of a NavigationView, then you can implement it using a simple ListBox with some minor styling instead. The fully featured NavigationView from UWP has a lot of complexity that most devs won't need. You could also use the implementation from FluentAvalonia

There are many cool custom themes for Avalonia, also default Fluent theme is already very good looking. Try for example this https://github.com/amwx/FluentAvalonia

But, going by the Avalonia route, you have the promising FluentAvalonia project for the Windows 11 look & feel. I was a bit overwhelmed by Avalonia when I tried it but especially for cross-platform projects it's of course a solid contender and probably a strong alternative to MAUI.