Writing a winning 4K intro in Rust | Hacker News Reader

Writing a winning 4K intro in Rust

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330 pointsDowwie89 comments

I love the demo scene, but the culture is kind of strange. Like I've been fooling around with the C64, and all the tools (emulators, debuggers, and etc) are hosted on source forge, or sometimes this random ftp. The author of the debugger I'm using proudly proclaims that he only works on it when he's fucked up on drugs after parties. The documentation of some tools has lewd ascii art, and etc etc.

I appreciate the anti-corporate vibe and at the same time wish they were a little more professional. Whatever you think, they're true 80s style cyberpunk hackers!

"On the one hand, I found a program that does exactly what we need. On the other hand, not-quite-dressed anime characters..."

I've had this exact conversation with coworkers before.

Which side were you on?

Which program?

"For research purposes.. of course..."

I recently explained to someone in an interview that I chose Puppet over Ansible circa 2014 because by default, Ansible used to output success or failure messages using cowsay.

Funny, that would make me want to use Ansible more.

As far as I am aware, the only known bypass of a particular iOS security mitigation has a note in it from the author notifying readers that they’ll only understand it after they “hit a blunt”. Said author also enjoys referencing Kim Jong Un in their work. It’s not just the demoscene that’s like this.

Probably developers sick of all programming being so sterile and corporate. You can't even publish a foss project without people jumping at you if its not suitable for a corporate environment.

> a little more professional

After witnessing how "professionals" act behind closed doors, the difference is merely a mirage, in order to not affect the business image.

Well, of course. A “professional” does not (cannot) behave professionally 100% of the time, the idea is that when doing work that interacts with others, that’s when you’re more professional.

I never have that requirement for any community I want to take part in to be honest. If I don't like it, I am going to look elsewhere.

What I consider unprofessional for example is banning people from your service because a mob demands it. Paypal is an example of a service for financial transactions that banned users fallen out of good faith. Here professional distance would actually make sense.

Imagine IT services giving out personal information of people they don't like, it is completely unimaginable. I think this is a real danger for large social media sites given the behavior of companies.

That's down to you having a different set of bad experiences than others. There's room for both of those things to be wrong, I think over time you get a broader and hopefully more nuanced sense for what kind of behavior is unprofessional and not beneficial to the social order of a project.

I've been working from home for a few months now... How about "suitable for casual family perusal" because screens are child-magnets.

"professional" is entirely about public image. If it's behind closed doors of course they no longer act professional. In some languages that value professionality there's even words built into the language. In Japanese there's the word "tatemae" 建て前 that translates roughly to "public position or attitude (as opposed to private thoughts)" that people hold while at work and they switch it off when leaving the work place/in private settings.

Being professional is entirely about being a good lier.

https://github.com/smabie Is it your github with a creepy kid picture? Very unprofessional!

>are hosted on source forge

Actually i like source-forge, it does not attract the twitter and facebookish folks as github seems to, aka

https://github.com/nikolas/github-drama

This github-drama repo has provided me with hours of time-wasting fun. Thanks for sharing!

Same ;)

EDIT: Maybe the best list to find future NO-GO applicants

I think it is a reference to the fact that Sourceforge used to inject spyware into published binaries.

Yes they did in the past...that's true...shady time's ;)

Quite the leap to derail the conversation into some anti-X agenda.

Ah...i see, if i like something i have to be anti against something else right? I like meat so i have to be anti vegan right?

Why not just accept that i like something but being absolutely ok with something else?

I think that's truly fantastic.

Can you articulate what the specific benefits would be if the person providing obscure free tools via esoteric channels suddenly conformed to the behavioral norms your wishing for?

TIL: about the Demoscene[1], "an international computer art subculture focused on producing demos: self-contained, sometimes extremely small, computer programs that produce audio-visual presentations. The purpose of a demo is to show off programming, visual art, and musical skills. Demos and other demoscene productions are shared at festivals known as demoparties, voted on by those who attend, and released online."

[1] https://en.wikipedia.org/wiki/Demoscene

There is also an active demoscene for microcomputers of the 80s, such as the Commodore 64 and the ZX Spectrum. And also people coding new games for them.

I'm glad these venerable computers live on.

Oh yeah, the Cracktro.

I never get tired of watching these things. Such a cool art form.

Sometimes they can be a lot of filler though. Yes you managed to create a 40 minute video but its 90% the same thing moving very slowly.

I'm surprised someone on HN since 2012 would learn about the demoscene today! Then again, it's true that the demoscene "keeps to itself", it's always been quite the bubble. I'm not sure how that community could do some outreach, but I believe a lot more people would find it interesting.

Something something lucky 10,000

For those not in the know, this is an xkcd reference: https://xkcd.com/1053/

It's a citation I want to give out surprisingly often.

Important to keep in mind the 10000 is in relation to the population of USA. On the scale of the whole world it's more like lucky 200000.

I wish HN had a top nav link and a mechanism like it has for “Show HN” posts, but for demoscene stuff. The prefix one would use could be “Demoscene HN” or something, and the rule would be the same as for the “Show HN” prefix – that using it is “allowed” only when the submitted of the link was involved in making the thing :D

Recently, Virtuaverse used Demoscene as part of a cyberpunk story.

https://www.gog.com/game/virtuaverse

> TIL: about the Demoscene

In that case, definitely have a look at this amazing write up (http://www.sizecoding.org/wiki/Memories).

I learned programming on the TRS80, and didn’t know about the demo scene until I was already too busy with other parts of my life; I think I first saw a demo on the Amiga.

I always feel like I missed out on something transcendental. I think I would have leaned a huge amount. Instead I had to settle with hacking NewDOS/80 binaries.

I have a huge amount of technical respect for the people who do this stuff.

I didn't know it existed until ~October(?) last year. My $lastEmployer (animation studio) had a demo day where in-house people would demo some personal projects they were working as well as exhibit entrants' works to the actual demo scene. It was insane, I would never dream of being able to produce most of the things I saw. If I remember correctly we watched demos from the 4K category to the 1 or 4M category. Procedural graphics, audio, emulation, it truly is an art form.

I grew up on BBS (started dialing at age ~6)

There were only two types of programming that intimidated me so much I wouldn't even try: people writing languages from scratch and the demo scene people. I just sat back and said "nope, I'll never get there."

Haha! I wrote a logo inspired language to do graphics programming. It was an interpreter written in BASIC. You didn’t miss much :)

I also wrote a BBS, so go figure...

It's never too late! Demoscene competitions happen all year round, around the globe. Some of the competitions are super focused and aren't a ton of work to do. The competitions (called "parties" in the scene) are a great way to spend a weekend with a bunch of like-minded nerds from many different disciplines: programming, graphics, music, ANSI/ASCII art, retrocomputing, etc.

I tried to share the link to this via fb messenger, and it blocked it because it "goes against our Community Standards".

A while back the same happened to pouet (https://twitter.com/pouetdotnet/status/1249453524758528000).

Demoscene stuff seems to be good at triggering the filters :)

That intro was very cool! Does anyone have pointers for a fullstack web dev who is interested in the demoscene (or computer generated art in general)?

I've actually played around a bit with rust [1] (I understand it probably isn't ideal for demoscence), but I haven't really done any graphics programming before. I get the feeling it is a pretty deep rabbit hole.

[1] https://github.com/dwaltrip/advent-of-code-2019-rust

> but I haven't really done any graphics programming before

I've never written any demos but do enjoy playing with GPUs. Regarding anything and everything graphics related, try not to get overwhelmed by modern APIs; it's very easy to lose the forest for the trees. Shadertoy is a really good starting point.

My impression of the demoscene can be loosely summarized as extreme code golf for graphics and sound.

That all makes sense. Thanks for the advice.

Javascript demos is one option https://www.dwitter.net/

That site looks pretty cool! Some very nice animations on there.

In this intro and in almost every modern 4kB intro, the graphics are made in a shader. To play with shaders, I'd recommend you to look at https://www.shadertoy.com/. Check also Inigo Quilez's website (https://www.iquilezles.org/), it has a lot of fascinating content.

Thanks for the links! Very helpful

If you're a web dev, then <canvas> may be the obvious option to get started! There's a fairly large creative coding community.

The Coding Train on youtube has a ton of content [0]. If you really want to start from the beginning then I would also recommend Coding Math on YouTube [1], which is sort of graphics from first principles using JS/canvas. That even starts with teaching trigonometry, vectors, etc. So if your math is rusty it's a good place to start

[0] https://www.youtube.com/user/shiffman

[1] https://www.youtube.com/user/codingmath

Thanks! I’ll check it out.

Kinda surprised about iterators not getting optimized so well. Even in higher-level languages, this is a commonly utilized optimization opportunity - e.g. the C# compiler will replace a foreach-loop over an array with an identical (but faster) for-loop.

Compiler optimizers are full of surprises going both ways: good and bad. And details like this can probably change from version to version and get affected by compiling options. I would also expect that performance is higher priority than code size, generally, so missed opportunities like this might go unnoticed and unaddressed a long time if they don't show up on performance benchmarks.

The classic example of surprising optimization is perhaps matrix multiplication in Fortran:

At some point in history, when you wrote the straightforward, primitive three-nested-loops version of matrix multiplication your code ran much faster than when you tried to implement one of the more sophisticated algorithms.

That was because the Fortran compiler recognised the primitive version and replaced it with a special purpose highly optimized matrix multiplication. The compiler couldn't do that with the more sophisticated approaches.

> The classic example of surprising optimization is perhaps matrix multiplication in Fortran:

> At some point in history, when you wrote the straightforward, primitive three-nested-loops version of matrix multiplication your code ran much faster than when you tried to implement one of the more sophisticated algorithms.

It might also have been due to Fortran using column-major matrix layout; if you try to implement a sophisticated multiplication algorithm that is optimised for row-major matrices, then that will be slower (indeed, also the row-major three-nested-loops version is already quite a bit slower). Another thing is that the sophisticated algorithms usually have some constant overhead that makes them shine only on sufficiently large matrices.

There are tricks/an art to Rust's iterator semantics.

One example I know of is that when trying to calculate a dot product, you can improve the generated code and elide the bounds check only by a very particular syntax:

    // Must slice to equal lengths, and then bounds checks are eliminated!
    let len = cmp::min(xs.len(), ys.len());
    let mut xs = &xs[..len];
    let mut ys = &ys[..len];
    let mut s = 0.;
    for i in 0..xs.len() {
        s += xs[i] * ys[i];
    }

https://users.rust-lang.org/t/how-to-zip-two-slices-efficien...

https://github.com/rustsim/nalgebra/blob/b1b18d17ee64d3fd28b...

Does it still elide the bounds check if you replace the first three lines with

    assert_eq!(xs.len(), ys.len());

?

Rust will do that too. We're talking about micro-optimization-level details, not allocation of iterator objects and so forth.

This isn't a case of a missed optimization. The alternative loop they've used has different semantics: assumes 0 iterations never happen. It's equivalent of changing `while(){}` to `do {} while()`. It's not something an optimizer could safely do when the number of iterations isn't known.

Looks nifty. Seems to only compile on Win though:

  $ xargo run
  For more information about this error, try `rustc --explain E0463`.
  error: could not compile `winapi`.

Still, probably good for interest/learning from. :)

Hm so it's leveraging the Windows API. I thought demos were supposed to be bare-metal.

The only way to achieve those kind of graphics in 4k is leveraging the Windows platform api. That is, unless you can drive a gpu and a soundcard from bare metal in 4k, while implementing the drivers and stuff for the hardware.

Most 4K demos on Pouet the last years has been Windows only. Demoscene parties usually specifies exactly what computer they will run the demos on in advance so groups can optimize for that setup. The code sometimes only run on that particular setup.

Using the OS is allowed. As far as I know, one of the reasons why there are more Windows demos than for example Linux, is that Windows provides more graphics/sound APIs out-of-the-box while on Linux the OS itself does less you'd have to utilize libraries (which is kind of cheating when doing a 4k demo).

I think it could be summarized as "write a demo for the target platform as efficiently as possible". Doesn't necessarily need to be bare metal, there are JS demos that run in the browser as well. In that case the browser (with all its APIs) is the target platform.

There's no such thing as bare metal today, unless you want to go from real to protected mode and fit a graphics driver in 4k. Basically impossible

On Windows, to show graphics, your program needs a window. To show a window you need WIN32 API.

This is important art.

I really enjoyed the artistic part. I wonder if the author was trying to evoke a Martian atmosphere with the color choices. The contrast of the spheres with the columns was very nice as well...the perfect, beautiful spheres ascending into the sky...

I'm not sure if the author is reading this thread, but thanks! :-)

As author mentions, it is non-idiomatic Rust with lots of unsafe's, basically writing C code with Rust compiler.

This is not true. Unsafe only disables a few safety features. There are still a bunch left on so unsafe rust is still more safety checked than C.

Care to elaborate? What are such safety features?

The only unsafe functionality the author describes is the unchecked array access. Based on that (which may be incomplete, of course), the borrow checker is a safety feature that is active.

The grandparent is wrong. Unsafe doesn't disable safety functions. From the big book of Rust Unsafety:

The only things that are different in Unsafe Rust are that you can:

- Dereference raw pointers

- Call unsafe functions (including C functions, compiler intrinsics, and the raw allocator)

- Implement unsafe traits

- Mutate statics

- Access fields of unions

https://doc.rust-lang.org/stable/nomicon/what-unsafe-does.ht...

The point is, unsafely calling `get_unchecked` is what's bypassing the range check feature. Not Unsafe itself.

I'm a little confused about what's happening here... Rust can run in an OpenGL shader ?!

This is old and may not even compile anymore, but it's short enough to give you an idea of what's going on.

https://github.com/ohazi/opengl-demo-rust

GLSL shaders are usually either loaded from files or stored as strings in your programming language of choice. The OpenGL library or bindings will usually have some facility to compile those programs and then send them to the GPU, along with textures, geometry, etc.

Always amazed by what people are capable of doing in 4K.

The music vibe reminds a bit of Brian Eno's Under Stars track from the Apollo album:

https://www.youtube.com/watch?v=dcWwtQmAt7E

Cool projects Some Rust macro magic could probably clean up some of that bounds checking.

Does someone know what the problem is with the intrinsics? Or is there a problem? The author states that this breaks his debug build for some reason.

I think the author called _mm_load_ps() on a pointer that isn’t 16-bit aligned. Either change that to _mm_loadu_ps() (which also works on unaligned pointers but incurs a performance penalty), or make sure your object is aligned when doing the heap allocation (there’s a STL function called aligned_alloc() in C++, probably there’s something similar in Rust)

Why would that only fail on debug builds and not release builds, though? That seems really strange to me

Debug and release builds probably call slightly different sets of methods, so they might end up with slightly different heaps. That might be enough to cause a difference in offset between the builds.

How do they view the use of libraries in this competition? Do the libraries count toward your 4K?

Its only the output binary size that matters. If the libraries are in there then it counts. Where it gets a bit funny is graphics libraries and gpu features. You wouldn't include vulkan in your size but you get a bunch of features that weren't available on older hardware.

Looking at the article, OpenGL seems to be allowed in that competition. No clue about other libraries.

Basically it has to run on a fairly clean Windows machine. The competition will usually publish the specifications of the machine ahead of time and what's on it. What you enter has to fit entirely within the bounds of the competition, but can use anything else on the machine if it's available. So you could enter say, a 4kb entry, and use a bunch of Windows .dlls for icons or something as artwork, but you couldn't enter a 4kb executable and 100MB of libraries and other stuff.

For some languages where this is really hard to achieve, they'll carve out a separate category for a language if they think there will be enough entries. e.g. a Java category where the entry fits with the space limit, but can use any other library in the default Java classpath, even though that's very very big. Likewise for different operating systems (Linux, MacOS competitions).

There's been a fantastic resurgence in retrohardware and a category called "old school/skool" for entries that have to run in MS-DOS -- which can be ultra hard as you have to code up a lot more of the runtime libraries like music, graphics rendering pipelines, etc.

It looks just great! Congratulations on winning it.

It’s hard to rationalize calling it a “4K demo” when you’re allowed to call OpenGL.

Yea, every rust programming is a challenge ;)

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