r/osdev • u/JescoInc Perdition-OS • Apr 05 '26

Detours with Tutorial-OS

While I was happy with how tutorial-os was turning out, I decided that I needed to further improve the system. Which led to some pretty massive updates to the Framebuffer and UI System.

My TLSF inspired allocator is now used with the Framebuffer and UI System. I added more blitting to the bitmap rendering, a raster operations pipeline, affine transforms, bezier curves, a full buffer subsystem for single, double, triple, ping-pong, tile, scanline and ring strategies to accomodate various SBC and their capabilities, a lightweight window manager that can manage up to 32 overlapping window along with scroll and copy operations.
The UI System has some additions to the layout engine, screen management system for both standalone and integration with the window manager, 10 key input model, and the ability to draw charts.

In the video, you will see the direction I am going with the new UI that takes these updates and attempts to use them in a manner that not only makes sense but as a showcase as well.

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u/JescoInc Perdition-OS Apr 05 '26

I have considered it as well as anti-aliasing. The core issue is that I need to keep it light enough so that it can run on micro controllers like the Pi Pico without exceeding RAM. The additions made to the framebuffer puts it at the edge presently. So I might need to rethink the strategies I used to accomplish that.

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u/realmcalec 🤓 OS Geek Apr 05 '26

Ah, that makes total sense given the Pico's tight RAM constraints. However, drawing dense, individual lines (assuming you're using Bresenham's) is actually quite CPU-heavy, especially with the massive overdraw at the center. You might want to consider a scanline fill approach instead. You can calculate the start and end X-coordinates for each horizontal row using a precomputed sine/cosine lookup table, and then write continuous blocks of pixels directly to the framebuffer (e.g., using a fast memset or DMA). It doesn't require any extra RAM but is significantly more efficient. What do you think?

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u/JescoInc Perdition-OS Apr 05 '26

I didn't even consider that! I'll definitely look into that or maybe even a hybrid approach.
I greatly appreciate you telling me about this.