Firedancer: Language for 2D shmups bullet-hell patterns
firedancer-lang.com
firedancer-lang.com
BulletML is a markup language that describes the barrage of bullets in shooting games. - https://news.ycombinator.com/item?id=410898 - Dec 2008 (2 comments)
https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...
I saw “applet” and thought it was retro, then someone tried it in firefox 3 and I had to check the year.
It was rrootage that sent me down a rabbit hole and eventually stumbled onto fal-works and firedancer after someone suggested their works had the same aesthetic appeal.
The libbulletml c++ library is still somewhat used in some niche vertical shmup games (mostly Japanese indie games). You can read a little about bulletml and the history of it all in the libbulletml readme file.
[0] https://en.wikipedia.org/wiki/ABA_Games
[1] https://github.com/abagames/rrootage
https://web.archive.org/web/20120626041044/http://www.libspa...
Haxe port: https://github.com/gunnbr/CML
As you may have guessed by the archive.org link, it doesn't have much support. Compared to BulletML and Firedancer, it has a very terse and rich syntax that kind of makes me think of Perl.
> bs,4,,10bm5,360f10{i30vw90br5,360,2,2f4{i30v~ko}w10ay0.05}
That is certainly terse!
[aside: I'm not usually one to pedant over what qualifies as a "markup language", but I have to say this is not it. I'm happy to report that the author didn't think so either, because the 'ML' stands for "macro language".]
Ah. I thought the script was being compiled inbrowser. These are prerendered.
One reason BulletML is useful compared to a general-purpose language is that you could arbitrarily recombine BulletML ASTs to produce valid bullet patterns, which Kenta Cho did for rRootage[0]. I think another reason that people implement VMs for these languages is that the host language lacks coroutines, so it cannot express the wait() function, and they don't want to turn their bullet pattern code inside-out. Even if the host language has coroutines, they may not be serializable, so saving your game in the middle of a level may not be possible if you build on top of coroutines, whereas it is definitely possible if you control the interpreter state of your DSL.
[0]: https://www.asahi-net.or.jp/~cs8k-cyu/windows/rr_e.html
Even in JavaScript, you might not want the full power of eval() exposed and instead you want something with less power that can be parsed and sanitized.
Personally, that's what attracts the artist side of me to this, like it's the ultimate creative product. There seems to be a lot of blogging and tweeting recently around the subject has also created a bit of an itch.
But where is the toothpaste laser? What even is a toothpaste laser? I hear you cry, well...
Today in Search Engines: Software for No-one, I try (somewhat naively) to search for "toothpaste laser" in hope of finding an accurate analysis/explanation/implementation of the famous weapon/s from the Raiden series.
It won't surprise you to learn that this got me a grid of photos of toothpaste tubes and mechanically-induced fluorescent grins. It might surprise you to learn that prepending 'raiden' to my query barely helped. If only there was a search engine that allowed the user to decide what to search for.
Long story short, Raiden (series) is about as popular as the intersection of Raiden (Kharacter) and referring to electrical arcs as "lasers"[1]. Both of these topics are totally eclipsed by the Bend-Tech Dragon A400: The Essential CNC Tube Production Machine[2].
[0] http://www.asahi-net.or.jp/~cs8k-cyu/bulletml/index_e.html
[1] not that any of the toothpaste lasers are lasers
[2] it is essential, after all (https://www.youtube.com/watch?v=xMb9XZjK6m0)
Video: https://www.youtube.com/watch?v=Vkr0mYdRZdU
More info: https://enterthegungeon.fandom.com/wiki/Raiden_Coil
It's even haxe based!
But why would vsync make that hard? You mean if it's 1:1 on the vsync?
If an enemy spawns e.g. a circle of bullets, you would see it rapidly expanding/contracting.
I suspect a variable frame rate bullet hell game would be harder to play, but I'm not a fan of the genre.
Games like Quake 3 do that, I think.
Inventing a language is the third step and even worse, because you not only have execution instead of data, but you wipe out the entire ecosystem of tools, libraries, fragments and knowledge and start all over again.
Says who? And for what definition of programming?
I'm not sure how you want it to be done without the programming part.
Maybe you should point out the parts that can't be static data.
Even branching, triggers or graphs could be straight data.
Which parts needs loops, state and computation?
I guess you could accomplish this with invisible bullets and making bullets targetable, but at that point, you’re just creating state and loops and pretending you’re not.
Then we write a new class or add new members to our class every time we want to do anything even slightly different. For example we'll have two members for doing a fixed angular and temporal step between bullets, then another for controlling the number of volleys of a fixed number of simultaneous bullets with fixed angular and temporal steps between them, then a couple more for controlling linear increases and decreases in the volley count, then when implementing Border of Wave and Particle we may as well add quadratic terms to all of the above (although we will only need one of them). Later we'll realize that our linear step-up-and-down knob doesn't actually differentiate between these sorts of things:
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To allow some enemies to aim some single bullets to the left or the right of the player, we'll just add an arithmetic expression evaluator to our location member too :)
Is that what the custom language is doing? Why would that be necessary?
Someone asked the question and I answered.
Even if you wanted to write new stuff, why not just use lua?
Sorry, I guess instead I should ask "How does your engine fire at locations that are evaluated in the past?" One way is to keep a queue.
Honestly this whole business of targeting locations in the past is not a dealbreaker to me. I don't know of games that need it. It's sufficient to implement this sort of delay by spawning some non-damaging thing under the player and having it spawn bullets later, or aiming at some time and then firing later.
> Even if you wanted to write new stuff, why not just use lua?
I listed some reasons here: https://news.ycombinator.com/item?id=41257693
Again, how does the language do it? If you query past values you can then know to keep track of past values.
Also there is no reason to use coroutines to make game bullets. You can just let a function keep track of state if it needs to and call it every frame.
At the core of all this is classic examples of over complicating things. As soon as someone declares they are making a brand new language with VM and coroutines to decide how bullets emit in a simple shooter, anyone else involved should be stepping in and putting a stop to it.
I don't think that asking for something causes you to have recorded it in the past! In the various languages you would aim and then wait. Here it is in Firedancer:
aim()
wait(18)
<action label="main">
<fire>
<direction type="aim">0</direction>
<bullet>
<speed>1</speed>
<action>
<vanish/>
</action>
</bullet>
</fire>
<wait>18</wait>
<fire>
<direction type="sequence">0</direction>
<bullet>
<speed>2</speed>
</bullet>
</fire>
</action>
> Also there is no reason to use coroutines to make game bullets. You can just let a function keep track of state if it needs to and call it every frame.
Quite uniformly, developers of bullet hell games do not want to separate their code into basic blocks delimited by any part that might involve time passing in the game, and they don't want to give up on subroutines existing. Turning all of your code inside-out and giving up on subroutines existing obviously makes the work extremely tedious and makes it hard to iterate or to know what's going on in some file you haven't touched in a week. I don't necessarily advocate for making a new language and VM, but if you review the tools people actually use for this stuff, nobody does what you say everyone should be doing.
For a third example, here's a danmakufu tutorial in which we learn that we should make Marisa's laser not freeze the game by adding a yield to a loop: https://sparen.github.io/ph3tutorials/ph3u1l5.html
I have done this stuff in lua, but in any real game I would probably want the game state to be serializable.
You don't think it's possible to read the file when the game loads, see a negative number, and save previous values?
in which we learn that we should make Marisa's laser not freeze the game
This seems to be a common theme with coroutines, the idea that it's solving a problem that can't be solved any other way (except for how it's been solved in the ten thousand other games over the last 40 years).
I have done this stuff in lua, but in any real game I would probably want the game state to be serializable.
That's why we were going to evaluate the locations that we could look into the past for on frames when we weren't looking for them. You decided it wasn't necessary to do so.
Can you link some of the ten thousand bullet hell games that are written in your preferred style? It seems like so far we have a lot of games written in one style that include certain kinds of complex behaviors and a lot of games written in another style that do not include these. So I am mostly comparing all of the output of ABA Games, ZUN, and almost every Touhou fan shmup on the one side to nothing on the other, rather than saying "wow, it's so impressive that people were able to make the amazing bullet patterns in Stephen's Sausage Roll with just switch statements!"
...What?
Can you link some of the ten thousand bullet hell games that are written in your preferred style?
Games without coroutines? That's almost every game ever made.
You realize most of these types of games originated in the 80s and 90s and were made in assembly right?
Here's where you dismissively suggested that evaluating and storing locations that might be asked for in the future was unnecessary: https://news.ycombinator.com/item?id=41266544
> Games without coroutines? That's almost every game ever made.
Bullet hell games? None? Honestly it took several tries for me to come up with a game that lacks an internal language and VM (e.g. StarCraft and WoW have at least 1 and at least 2 respectively). Stephen's Sausage Roll seems like a potentially winning bet only because I don't think you can make all of it in PuzzleScript, which is what the author normally uses.
> You realize most of these types of games originated in the 80s and 90s and were made in assembly right?
There weren't any of these games prior to Batsugun in 1993. According to the people who have reverse engineered the games, the more well known DoDonPachi DaiOuJou in 2002 used the same level planner that Toaplan used for Batsugun. Assembly obviously has coroutines, but we know that these games did not use a coroutine implementation for their bullet patterns. I obviously don't work at CAVE and can't just ask the devs what they were thinking, but if you play these games on the original hardware, even though every bullet has no behaviors attached the game will start to run slow when there are a lot of bullets on screen (and the game seems to be tuned around this fact). So I expect that even if the developers wanted to make the sorts of things we have in modern games, they would run too slowly to be practical.
To be fair, modern games that use danmakufu or ZUN's ECL or BulletML or Firedancer or Lua would probably have less distinction between "enemies" and "bullets" and the "enemies" in these games often do have some behavior attached. In the case of DoDonPachi DaiOuJou, each enemy that spawns uses one of a small fixed table of movement patterns.
I'm not sure what the claim about "most of these types of games originating in a certain time period" really means. A majority of bullet hell games were probably made in the last decade, and that will probably continue to be true for a long time. If you mean that it's common for these games to contain references to games from the 90s, I agree, but that has nothing to do with whether modern games are written in assembly or how the behaviors are scripted.
What you actually said was "evaluates all of the Locations that any pattern could ask for every frame" so you are being very dishonest.
None?
You think no video game has ever been made without coroutines?
I'm not sure what the claim about "most of these types of games originating in a certain time period" really means.
What is there to process here? Games in the 80s and 90s were made in assembly language, then C. There were lots of shooters in those two decades, clearly they didn't need coroutines to make bullets and no other game did either. I don't even know how someone gets into a mindset that some shiny programming feature they love is the only way to do things when decades of progress before had nothing to do with it.
Lua didn't even have coroutines until 2003.
Sure, I think that's a reasonable implementation. Maybe we know all the Locations for all the behaviors in the current stage, and of those, for each one that can be evaluated in the past, we should evaluate it each frame and store it in a collection. The stored past-locations that are old enough that they can no longer be asked for can be discarded. So the data is accessed like a queue normally, but maybe if multiple behaviors look into the past by different amounts for the same Location then one of them has to access the middle of the queue. This is fine because the queue can be backed by a circular buffer. Is this a bad implementation in your view?
> You think no video game has ever been made without coroutines?
Is this an honest followup after someone asks exclusively about games in a single genre?
> What is there to process here?
Well, if the claim is that a majority of all bullet hell games were made before 2000, then it's just false, but it's sort of unclear if that is the claim. Maybe the claim is about "types" rather than "games." Even if it's about "games" then maybe Touhou Hisoutensoku (2009) "originated" in 1994 with the release of Street Fighter.
> Lua didn't even have coroutines until 2003.
Assembly had them in the 1960s (well, they are first documented to have been used in the 1960s, despite existing before then). C had setjmp and longjmp in 1979. Why would Lua need them?
To review the situation, we have 0 bullet hell games from the 80s. We have some bullet hell games made starting in 1993 by 2 companies (one of which is made up of the staff from the other) with exclusively bullets that never turn, home, accelerate, bounce off of things, or spawn other bullets. The games by these companies use a stage plan format the execution of which could reasonably be described as "not a VM". We have numerous other bullet hell games, the vast majority of all bullet hell games ever made, that use imperative scripting languages that can execute a single function that spans many in-game frames to attach behaviors to bullets. We also have a number of bullet hell games larger than the number of Toaplan/CAVE games but smaller than the number of BulletML/ECL/Danmakufu games for which I can't make any claims either way about the scripting environment (Valkyrie Sky, Jamestown, Shikigami no Shiro, etc.).
Obviously it's possible to implement anything in any Turing-complete language, in the same way that Billie Eilish could simply type the waveform she wants to put on her album into a text editor if she wanted to. I just think that it might be unreasonable for people who have sold 0 albums to tell her to do that instead of using FL Studio or whatever.
That's what you think I said?
C had setjmp and longjmp in 1979. Why would Lua need them?
I don't know what this is supposed to mean, all I said was that lua didn't have them until 2003.
I can't even follow what you're saying, you're all over the place.
Are you really trying to say every video game ever made uses coroutines?
Yeah I think that usually "most of" means "a majority of" and "originated" means "was created."
> I don't know what this is supposed to mean, all I said was that lua didn't have them until 2003.
Well, I guess I apologize for assuming that that was supposed to be relevant.
> I can't even follow what you're saying, you're all over the place.
This submission is about a tool for creating a specific genre of art. Some works of art are created in an iterative process where the artist repeatedly evaluates and perturbs the work to make it more to their liking. Some ways of working make this easier than others. Almost every work in the genre has been created in a specific way. This submission's content is a part of the same tradition that includes the tools that have been used to create the vast majority of works in the genre. If someone who knows nothing about any of this insists that almost all of the artists are doing everything wrong, well, the base rate for that person being correct is not great.
> Are you really trying to say every video game ever made uses coroutines?
No. I gave specific examples of games in this genre that are known based on reverse-engineering to not use coroutines.
I will venture to avoid spending my time writing words for low-literacy audiences from now on.
What are you even talking about? All I said was that shooters in the 80s and 90s were done with asm. Why is every comment so far off the map?
I will venture to avoid spending my time writing words for low-literacy audiences from now on.
It's definitely not that you have huge ranting comments full of indecipherable tangents.
What was your point with all this again? I lost track of whatever you're trying to say a long time ago.
Just the same thanks for sharing and I'm enjoying playing around with this !
I just wish I wasn't so hopeless at them, only managing to survive seconds at a time by constant credit feeding. While I realize the entire genre is notorious for being brutally difficult and that's in fact the appeal to many serious players, I dream of shmups where:
* Difficulty scaled dynamically up a smooth gradient based on real-time player performance
* Success didn't require deep level and pattern memorization. My cognitive style is anti N-back and this requisite shmup ability remains forever beyond my reach. I need the shmup equivalent of Fischer Random Chess (aka Chess960) where the necessity of book memorization is removed and the focus is mostly on reactively dodging in the moment.
* The engine supports interactive practice modes enabling weaker players to gradually build skills such as: rewind, ghost follow and partial dynamic slowdown (eg only bullets get slower, only when N of bullets > Threshold, growing gradually slower as N increases, returning to normal below N).
On the last point, some modern shmups do at least have "practice modes" but they seem like developer afterthoughts, typically very basic bolt-ons instead of being integrated, dynamic and granular. The result often leaves me feeling more frustrated than trained. While it is possible to apply hacks to emulated shmups which can help a bit, these are usually limited to brute force such as pause, global frame rate limiting and infinite lives or invincibility. While MAME and Retroarch do have rewind features, I believe they are hacky since I've never been able to get them to work reliably with shmups.
My deep attraction to the genre seems doomed to remain unrequited despite buying and playing so many, watching various training videos and following many guides. I feel like I can't reach the level needed to trigger the fun-obsession loop of a typical bullet-hell shmup because it currently requires a minimum level of a few neuro-competencies I don't possess. Even top players and fans admit (and occasionally revel in) the inaccessibility of the genre, highlighting the need to memorize deep pattern sequences, commit dozens of hours to rote practice and how it helps to be "at least a little on-the-spectrum."
This makes me sad because top players, fans and developers are also worried about the long-term decline of the genre from cool niche in the 90s to seriously at-risk in recent years. I suspect there may be others who are, like me, strongly attracted to shmups but too-often barred by a metaphorical "Must Be This 'Neuro-Level' to Ride" sign. Yet other once niche gaming genres have successfully broadened their appeal by deeply integrating 'accessibility' features like racing games have done with: ghost cars, rewind and suggested driving line/speed indicators, and fighting games with granular, smooth-scaling training modes with extensive on-screen instruction.
[0]: https://www.youtube.com/watch?v=5LQ3a5D2OKY&list=PLMDuVHl1iO...
I love the shmup genre, but would rather play traditional ones like Raiden, DemonStar, R-Type, Gradius, Blazing Star, etc., and modern entries like Sky Force, than Ikaruga and the like. But, hey, to each their own. :)
R-Type, on the other hand, is a pure memorisation game, much more so than Touhou or Donpachi, and definitely features the same patterns every single time.
What I meant is that when there is a pattern in the objects you have to avoid, and the number of them becomes overwhelming, it doesn't make the gameplay more enjoyable (IMO). Those micro movements you mention surely require a lot of skill, but to me they're just not fun.
Take a game like The Binding of Isaac as another example, whose core mechanic is a shooter. Twin-stick shooters are an evolution of the shmup after all, where the player is in control of their attack direction. What makes TBoI so much fun is the unpredictability of enemy movement and randomness of objects you have to avoid. It does have areas where attacks are overwhelming, but player progression is usually well balanced (though it is possible to become overpowered as well :), so it's never just a dodging game.
But I concede that my experience with bullet-hell shooters is limited, due to this initial dislike of their core mechanic.
On a slight tangent, this is why I don't see the appeal of the recently popularized "survivors-like" games. Sure, there are swarms of enemies, but they come at predictable patterns, so the main mechanic is just strafing around them. Add to that that they remove your ability to aim or fire, and the gameplay boils down to just using directional keys in a specific order. It's so boring and unengaging. But then again, there are entire genres of clickers and idlers I don't get either, so this is purely a subjective take. :)