> Windows' Sleep() function has default resolution 15.6ms, that's not enough for realtime rendering, and relatively hard to fix

Very easy to fix. Call this at the start of your real-time process:

https://learn.microsoft.com/en-us/windows/win32/api/timeapi/...

Use an argument of 1, and windows will come knocking at ~1Khz. This is extremely effective in my experience. Allows you to do some pretty crazy stuff on 1 thread.

No direct access to the command buffers of the GPU? No matrix transform routines? No colorspaces besides RGB? Absolute non-starter.

> direct access to the command buffers of the GPU

Impossible given the platform limitations at that time, on Linux that code works on top of GLES 3.1. I didn't want too many Windows-only features there.

> No matrix transform routines?

There's no need for that. That library is for C#, which includes these routines in the standard library of the language for many years now, since .NET core 1.0: https://learn.microsoft.com/en-us/dotnet/api/system.numerics...

My remark was about Fenster, and a critique of your comment that it somehow isn't good enough because it lacks GPU acceleration and that sort of thing. The point of Fenster is to be minimal and simple yet still allow programmers to get stuff on the screen in a way that's easy and fun. It performs superbly at the role it was conceived for. We can list features we want/think are table stakes for a modern graphics pipeline or whatever, and there are plenty of libraries that are up to those tasks. This one is doing something different.

There’s simple and there’s naive.

SDL already walked this path. So did pygame.

It turns out without shaders, and all their complexity, you basically can’t do anything useful at high resolutions.

/shrug

It’s too slow; compositing, transformations, all the things people want to do are very much harder to implement in software on top of a naive graphics stack.

Simple doesn’t mean naive; you can have a simple api that is excellent.

…but this is a naïve implementation, and it won’t work in any useful way at scale.

People complain about ballooning complexity, but they often forget that stuff (eg. specialised graphics hardware) wasnt invented by a bunch of idiots.

It was invented because the naive approach, that they used before was found to be in practice fundamentally limiting, inferior and failed to meet people’s expectations.

Of course, if you vastly lower your expectations, and target say, 320x240 at 8bit colour, you can happily have a naïve implementation that works just fine…

For any graphic intensive application it would be obviously be necessary to use a GPU.

But for quick hacking / porting old demos / writing emulators and also text based UI it can be fast enough.

With the added benefit of small footprint, high compatibility and fast startup time.

The Lite editor https://github.com/rxi/lite is using pure software rendering (on top of SDL) in a rather naïve fashion but it still renders full 32bit colors at full resolution at more than 60FPS on my computer, not the best solution but still surprisingly fast given the simplicity of the renderer.

This is typically a case where simple/naïve can beat a juggernaut like Electron.

> is using pure software rendering (on top of SDL) in a rather naïve fashion

https://github.com/rxi/lite/blob/master/src/rencache.c#L4

I think you'll find that they found the naive approach was sufficiently poor, performance wise, that additional optimizations had to be applied on-top.

> But for quick hacking / porting old demos / writing emulators and also text based UI it can be fast enough.

/shrug

If you want to use it, use it. It's 'good enough'...

> if you vastly lower your expectations

> No direct access to the command buffers of the GPU?

Lol, show me one library that does this without going through an abstraction layer like Vulkan. Details like this are not even documented by GPU vendors and you'd need to reverse engineer every supported GPU architecture yourself.

I was being sardonic.

Guy writes a library with the design goals of making basic, retro-like graphics functionality easy and fun with a minimum of code, and certain Hackernews dogpile him because it can't be integrated with an AAA pipeline or whatever.

Ah, apologies then :)

> For the rendering, ideally it needs GPU support.

It's a 2D framebuffer library for placing single pixels like in mode 13 *eyerolling* (GPUs are hardly useful for this type of stuff).

If you want something more complete, check out the sokol headers (shameless plug): https://floooh.github.io/sokol-html5/

...but that can hardly be called 'minimal' anymore.

2d graphics are rendered on the GPU nowadays, and rightly so. Even SDL uses the GPU wherever it can, by default.

That's a silly statement. If you want to place single pixels, a GPU won't help in any way. The most efficient way would be to write pixels with the CPU into a mapped GPU texture, and then render this texture as fullscreen quad. That's hardly more efficient than going through the system's windowing system.

For applications like emulators, or making vintage games (like Doom) run on modern platforms, that approach makes a lot of sense.

Most vintage systems use something way more complex than a pure CPU-controlled framebuffer for graphics. They generally have some sorts of pre-defined "tiles" used to implement a fixed-width character mode, with the addition of a limited number of "sprites" overlaid in hardware. These video modes could be implemented efficiently by modern GPU's.

Only if you don't have a cycle correct emulator inbetween. Those old school system relied on hard real time timings down to the clock cycle to let the CPU control the color palette, sprite properties etc... at the right raster position within a frame. Modern GPUs don't allow such a tight synchronization between the CPU and GPU, so the best way is to run the entire emulation single-threaded on the CPU, including the video decoding.

(the resulting framebuffer can then of course be dumped into a GPU texture for rendering, but that just offers a bit more flexibility, eg embedding the emulated system into a 3D rendered world)

It depends what you mean by "hard real time". In theory, user input you get while scanning out pixel x might change pixel x + 1, and this leaves you with no choice but rendering single pixels in a strictly serial way. In practice, no existing emulator cares about that.

It's not about user input, but the CPU writing video hardware registers at just the right raster position mid-frame (to recycle sprites, change the color palette, or even the resolution). Home computer emulators for systems like the C64 or the Amstrad CPC need to do this at exactly the right clock cycle, otherwise modern (demo scene) demos wouldn't render correctly.

PS: of course one could build a GPU command list to render such a video frame somehow, but I bet just building this command list is more expensive then just doing the video decode with the CPU. It would basically come down to one draw command per (emulated system) pixel in the worst case.

>That's hardly more efficient than going through the system's windowing system.

My intuition says otherwise but I admit I don't have math on hand to back it up.

Ok it's most likely slightly slower, but not enough that it matters. Frame latency might actually be lower though if the result doesn't need to go through a swapchain AND the window system composer.

But wouldn't the GPU help if you were mapping e.g. 256x192 virtual pixels to say 1024x768? I.e., each of the pixels from the low-res space being represented by a NxM patch of actual screen pixels, like a Win32 GDI StretchBlt() call.

If you had a frame buffer for the actual screen and you tried to do even a 1 to 2x2 expansion on the CPU's time, that'd have to be a serious speed hit. Presumably GPU hardware can do that sort of thing.

Yes, for fancy upscaling or applying pixel shader effects like CRT filters, doing the final pass on the GPU definitely makes sense. This would no longer be a "minimal" library though.

Window system composers should also be able to upscale bitmaps on their own though, and nothing prevents them to use the GPU for this.

Doing this through the GPU is actually somehow A LOT slower on at least Windows than going through the windowing system.