Complex Behaviour from Simple Rules: 3 Simulations

A small display of some of the surprisingly intricate patterns and behaviours that can arise from relatively simple rules. More information about each of the simulations below.
These simulations were made in Unity, and coded with C# and HLSL.
You can find the project files at the links below.
Reaction-Diffusion: github.com/SebLague/Reaction-...
Cellular Automata: github.com/SebLague/MN-Cellul...
Slime mould: github.com/SebLague/Slime-Sim...
If you'd like to support my work, you can do so on Patreon: / sebastianlague
--- 1. Reaction-Diffusion ---
This is a simulation of two chemicals (A and B). Both diffuse over time (A faster than B).
The simulation space is initially filled with A, and just a small region has some of chemical B. Over time, more A is gradually added (controlled by a parameter called feedRate), while B is gradually removed (controlled by the parameter removeRate). Finally, there's a reaction that takes place: when one particle of chemical A is in the presence of two particles of chemical B, it will be converted into B.
One could simulate the individual particles of both chemicals, but more common (and the approach I went with as well) is to just store a value for the concentrations of both chemicals at each pixel. The probability of an A particle coming into contact with two B particles can be determined by the equation: probablityOfReaction = concentrationA * concentrationB * concentrationB. Here is the tutorial I followed when creating my implementation: www.karlsims.com/rd.html
The colours in the simulation are mainly based on the concentrations of the two chemicals, but to spice things up I also added some colouring based on how fast the concentrations are changing at each point.
--- 2. Multiple Neighbourhood Cellular Automata ---
This is a technique developed by someone who goes by Slackermanz online (you can find many awesome examples under that name on Twitter).
In this simulation, the state of each pixel (called a cell) is initially randomized between 0 and 1. On every frame, the state of each cell is updated based on the states of all the cells inside various "neighbourhoods" around it. These neighboughhoods are ring-shaped, with each ring defined by a min and max radius, along with two min/max values called 'alive' and 'dead'. Once all the states inside a ring have been added up, the sum is compared to the ring's alive and dead ranges, and depending on which range the sum falls into, the cell's state increases or decreases by some small amount (if the sum is inside neither range, the state remains the same).
This already gives interesting results, but there are some more nuances that can be added. For example, instead of the rings directly affecting the cell's state, they can contribute to several 'potential' states, and whichever of these is most different from the cell's current state becomes the new state.
My implementation is based on Slackermanz code, which you can find here: github.com/Slackermanz/Vulkan...
Slackermanz also has a KZbin channel here: / @slackermanz
--- 3. Slime Mould Simulation ---
In this simulation we have a lot lot of particles, each of which leaves a trail behind itself as it moves. These trails diffuse and evaporate over time. Each particle also has three circular sensors arranged in an arc in front it. These are used to detect the intensity of the trail, and the particle turns towards whichever detects the highest intensity. Some randomness is added to the turning as well.
The idea for this comes from this paper: uwe-repository.worktribe.com/...
I also have a video exploring it in some more depth: • Coding Adventure: Ant ...
Music:
Beneath the Stars by Joshua Spacht
Nowhere I Can Go by The Stolen Orchestra
The Art of Loneliness by Anbr
Selfless by Eleven Tales
Life by Anbr
Chapters:
00:00 Reaction-Diffusion Simulation
02:50 Multi-Neighbourhood Cellular Automata
07:23 Slime Mould Simulation

[@alexanderlinderson2655]

Suddenly these particle systems start questioning their existance and whether they're alone in the unityverse.

[@DrunkGeko]

And simulating other smaller scale particle systems

[@nathankamenchu1239]

@@DrunkGeko turtles all the way down

[@jakehix8132]

Some say, if you zoom in close enough on the particle system making particles, you can hear them taking Sebastian's name in vain.

[@taureon_]

when one of those creatures suddenly "died" after pulsing for so long it made me sad

[@unitysparticlesystem]

I have no idea what is happening...

[@simivb]

I'm just glad you exist. This is nice.

[@wistlov9248]

I wholeheartedly agree!

[@diegopalo4073]

Same 💪🏻💪🏻

[@flashplays6489]

Wait 12 hours ago for me it shows the video released 12 mins ago

[@rikittu]

@@flashplays6489 he probably release videos a day earlier for his patreon supporters. The video is unlisted till the time of the publix upload.

[@terry2295]

I edit the comment because I asked the same question as Flash Wally above me and Ritik Tandon already answered it so no need for my comment

[@capsey_]

This is incredible how these simple rules make so organic-looking shapes, if someone would say that this is a new video from microscope I would fall for that

[@arielgenesis]

It is the other way around. Organic shapes that arose in the natural world comes from these simple rules.

[@BrewalRenault]

It's quite related to the principle of emergence. You should take a look at this Kurzgesagt video if you haven't done yet : kzbin.info/www/bejne/Z2e6aJZmosdgqKc

[@aceman0000099]

It goes to show, life isn't as complex/mysterious as you may think

[@SolarShado]

@@aceman0000099 It kinda is, and kinda isn't. IMO this (sort of thing) is a great example of how complex structures can emerge from even simple rules, and why it's unreasonable to *not* imagine the even more complexity could emerge from more complex systems. If you can get all this from only 2-3 "particles" with a 1-2 "forces", scale it up to what we have in reality and... >gestures vaguely in every direction

[@stickguy9109]

@@BrewalRenault Ah, i see you are a man of culture as well

[@lonebeaver9535]

Me: Barely gets a finite state machine to decide between eating and fleeing from enemies Sebastian Lague: Creates the building blocks of life all on his GPU

[@YTRingoster]

i mean, if you ran a million of your FSMs on the GPU and gave them pretty neon colors, it'd still look pretty cool

[@connorconnor1631]

Username checks out

[@SebastianLague]

Hey everyone, I know this one's a bit light on explanation -- I've just been having a lot of fun messing around with various simulations and wanted to share some of the results. Might do a more in-depth video on these techniques at one point if there is interest (for now though, the description has more detail and some links if you're curious). Hope you enjoy the video! The second simulation is based on the work of Slackermanz, if you'd like to see many more awesome examples of what can be done with this technique, make sure to check out Slackermanz' Twitter and KZbin over here: twitter.com/slackermanz kzbin.info/door/moNsNuM0M9VsIXfm2cHPiAvideos

[@dadutchboy2]

those arent simple rules, they are actually quite complex you can tweak them in very many ways too

[@rohanasokan7338]

Been loving your videos. It would be great if you start a tutorial on how you make these videos - they look so smooth and honestly the best I have seen on youtube. Cheers!

[@franciscomagalhaes7457]

I don't suppose anything like this can be at least emulated using webgl, for a browser experience, right? I've been trying to research how I would make cellular automata solely using webgl, but feel like I might have to hack together something suboptimal, since resources on the subject seem to be few and far between...

[@TheKennethConner]

It is so amazing how you are tweaking them and changing the rules mid-simulation! It's like a fireworks show! I love it!

[@JuanPablodelaTorre]

@@franciscomagalhaes7457 I'm sure it is possible to translate these to Javascript and WebGL. But you'd be better off using regular 2D canvas instead.

[@cheimy2347]

At 4:50 I see nice little happy particles traveling alone and than finding their friends and dancing together

[@taureon_]

and then one of them suddenly dies

[@cheimy2347]

@@taureon_ yes. He sacrifices himself or is eaten... Up to you

[@101m4n]

And only occasionally eating eachother

[@thomb.9013]

me too! i also thinks its nice for like a unstable essence if you take one that is like alone and still.

[@pinkajou656]

Me too! They also almost look like they have two hands holding each other’s.

[@lorenz.f]

It's incredible how lifelike those behaviours are. While this of course has much simpler starting conditions and rules then our world, it makes it much easier to imagine our universe just randomly formed from noise interacting with itself.

[@billowen3285]

My question is where the movement (life) came from?

[@kajetanradulski9267]

@@billowen3285 thermal energy

[@borisengler8892]

What if there are just few simple rules of our universe that make up other rules we observe as complexity rises? Just an idea.

[@antoninjacob2232]

@@borisengler8892 it's basically it. The universe was just pure energy at the "beginning" (even if it doesn't make sense to even conceptualize a beginning, which implies time that is relative). You couldn't have simpler conditions, and everything emerged from there. But the universe's laws are... Universal, all across itself, and very simple

[@billowen3285]

I don't know, understanding gravity makes my brain hurt

[@anonymouscommentator]

Holy moly and the music gives exactly the right atmosphere back. You truly feel like you are gazing at something special.

[@terry2295]

totally agree

[@_Wombat]

funnily enough I wasn't feeling the music. I muted and put my own on for a change :) each to their own

[@Crozz22]

Almost getting the feeling that one of these simulation would suddenly become life

[@MinerBat]

actually, theoretically that would be possible if the simulation size and time are many, many, MANY times larger. but even the strongest supercomputers don't get close to that calculation power.

[@canaDavid1]

Hey

[@fizipcfx]

@@MinerBat yeah like, the famous game of life takes its name from that theory.

[@samuelthecamel]

Now I understand why people think we're living in a simulation

[@aceman0000099]

@@samuelthecamel why would it matter though, if the "simulation" is identical to nature?

[@okyeahbutwhythoe1804]

I’m calling it, in 4 years you’re gonna make a “I Simulated All Of Reality” video

[@AbdullaJaberAL-Khafaji]

If the right computational power exists this will be easier than you think , just put the universe simplest rules in a simulator and there you have it , a reality simulation

[@okyeahbutwhythoe1804]

@@AbdullaJaberAL-Khafaji arguably you’d need all the rules, if you use Newton’s equation for gravity sooner or later it would look completely different from what should have happened and if you don’t use quarks stuff would not weigh nearly as much as it should

[@bowiemtl]

@@AbdullaJaberAL-Khafaji I highly doubt that

[@pascha4527]

if you want to create a big simulation, you'll have to have the compute unit for one atom be less or as big as one atom.

[@JohnSmithXL]

@@okyeahbutwhythoe1804 yeah, but if you think about it you could code in only quarks, leptons, and bosons along with simple rules on how the interact with everything and it should work just fine with the only worry being the cpu and ram needed to support such a simulation, do know that I'm not an expert in this stuff so I'll admit that there might be a problem with my statement.

[@BrodieEaton]

That second simulation looks like I'm watching micro-organisms through a microscope, and that "Thanks for watching" slide is by far the coolest end to a video I've ever seen

[@CodeBeetle]

I don’t care that my mobile is in 3% battery. I can’t stop watching it. It’s satisfying .

[@theepicgamer1196]

Big brain moment: watch the video AND charge your phone. Mind-blowing.

[@PaprikaYT]

Its so goddamn mesmerizing. Honestly im glad you are here for us. You taught me to not always strive for a super awesome scalable system that never gets done but just write the goddamn code and then see if the performance is good enough. That made me a better Programmer. Thank you

[@dottormaelstrom]

This looks like a video that's gonna end up in everyone's recommended 10 years from now

[@quearaeoquazhkn3728]

ye

[@TebiByyte]

I'm a simple man. I see a new Sebastian Lague video, I watch. But seriously this is so cool. It's like watching microbes under a microscope.

[@nmbileg]

following this channel since 2017 and I'm telling you guys, this guy is a freaking GENIUS. I hope Sebastian become a leading entrepreneur in our software industry one day. - Proud Patreon.

[@bronsoncarder2491]

What I would love to see is a combination of all of these ideas. Take your planets that you've generated with their beautiful atmospheres, use your erosion function to make them look super realistic, add your amazing clouds, populate the oceans with fish using boids, create an ecosystem of rabbits and wolves and ants. Literally combine everything you've ever done on the channel. It would take days to render a frame, but I wanna see it. lol

[@brotherbumkin3010]

I think we are almost waiting for it

[@tecumstudio]

I knew you were good from the time I subscribed to your channel. But you've reached a level where the code at your fingertips can even now turn into art. Not to mention, it must be admitted, that some of these behaviors automatically make you think about life at different times or places or even at different scales. You are truly impressive, breathtaking.

[@YMandarin]

these movements look so natural. When you try to make natural looking movement, it rarely looks good, but this looks really good

[@petersmythe6462]

Part of it is that these sort of emulate nature.

[@orionsyndrome]

and the other part is there is no movement, only continuous change of finite elements

[@EctoMorpheus]

@@petersmythe6462 cellular automata really do not emulate nature, at least not on the scale of individual cells.

[@adamprice4658]

What a great way to start my day. Sitting here with a cup of coffee, watching art unfold in front of me and listening to some well-chosen music.

[@PandemoniumGameDev]

This man started out by making games and now he's creating new life forms 😁 Amazing!

[@xxTshestoxx]

This is genuinely one of the most fascinating, astonishing and relaxing videos i have seen in a long time. Thank you for listening to your viewers suggesting this kind of video!

[@MichaelJOneill333]

8:30 absolutely amazing. You have a gift in programming and understanding of the fundamentals of biology. Thank you so much for this.

[@TheBibitesDigitalLife]

Welcome to the world of artificial life 😁 Amazing video as always! I loved how you used shifting parameters mid-simulation to bring forth variation and shake things up

[@SebastianLague]

Thanks! :)

[@pinkajou656]

@@SebastianLague this video is amazing!

[@gareths]

It's amazing how you incorporate music that perfectly encapsulates what I feel when I watch any of the simulations you make

[@themihanoid5020]

Videos like this make me think that life might actually not be that uncommon

[@oiacopas]

Great video, as always. I stumbled upon cellular automata and reaction-diffusion algorithms, when i started getting interested on programming and, since then, I've been under their spell. I can't quite put my feelings into words, but I get emotional when seeing complexity arise from such a simple set of rules. It's almost like I'm looking directly to a fundamental concept of reality itself. Glad to see you exploring this world once again!

[@Gwilo]

comments: from 12 hours ago video: from 20 minutes ago everyone: time travellers

[@epicfilms4life507]

everyone: patreon supporters

[@franzusgutlus54]

Ergo: patreon = time Machine Got it...

[@Gwilo]

@@epicfilms4life507 god damnit I'm getting my wallet

[@GoTeamScotch]

This was wayyy more interesting than I was expecting

[@Kamzik123]

Sebastian: *makes simulation video* KZbin compression: *starts sweating profusely*

[@zgolkar]

Outstanding how the music and art were matched at every moment to fit together. Admirable attention to detail!

[@constance8254]

WOW... just wow... At first I was disappointed not to hear you explain your code and the steps to get there because you usually explain in a very nice way (and your voice is very enjoyable haha) but I must say, I'm astonished. This is extremely wonderful, and the match with the music is just perfect. I didn't know a video of simulations could make me cry ! Thank you, and please never stop making videos, you're a genius !

[@kelvindecosta5350]

This is really missing his voice but it's still a fantastic watch

[@confusioned2249]

I swear this is the exact type of video youtube recommends you at 3 am

[@KalleBlixtHagholm]

Absolutely stunning! And the editing and timing the music makes it amazingly good. I want this as a screen saver to run on my TV.

[@flymacseamus3474]

9:00 I love that even though this is 2-dimensional, it looks like this has depth... I don't just see a slime simulation here, this looks like the large-scale structures of the universe

[@JC-jz6rx]

Your latest video blew up. So I’m writing this here in the hopes that you see it. Your channel is exploding recently , and it’s no wonder with all the effort that I can tell goes into the videos. They are great fun to watch! And as a developer , seeing how others approach problems is a great help. Thank you for reading, and thank you for making them Sebastian!

[@kathenae]

"So, which one was your favorite?" me: YES

[@henrymarkson3758]

Slime, hands down

[@mauritspuggaard4689]

You deserve so a lot more subscribers! I’m finding myself watching your videos multiple times. Great work as always!

[@AgsmaJustAgsma]

I stated in a Discord group that Sebastian is a quantum physics Unity tutor, and I'm glad that my statement holds true with each new video.

[@ooffoo5130]

you are the only youtuber who gets me genuinely excited when you post videos

[@SomethingExtra]

oh yeah baby cant wait to get uncontrollably connected with these behaviors that i try to do them myself but fail horribly

[@Gwilo]

BIRD MAN

[@pseudofred_]

Just some more ABSOLUTELY stunning visuals from Sebastian! Well worth the watch. Have been thinking of trying some of this out myself, looks like a deep rabbit hole of experimentation.

[@matheusmoreira9632]

That pleasure of seeing Sebastian Lague videos! Amazing as always!

[@roquendroll]

Slime Mould Patterns: *organically turns into hexagons* Me: "The hexagon is the bestagon" - CGP Grey

[@PauloHenrique-em2ly]

This is one of the most beautiful things i have ever seen. This is art!

[@commodoreNZ]

Mesmerizing and beautifully edited. I'm happy this is in my head now. Thank you and more please :)

[@nikoskonstantinou3681]

This is AMAZING. I could watch these simulations all day! Next step is making a screensaver out of this 😅

[@TriDeapthBear]

I can tell you've lost yourself in creating these simulations, and rightfully so! They're all super incredible, especially considering the basic principles they're made from

[@Arrogan28]

I have written shaders for many years, film, games, etc, going back all the way to the 90's and i have to say, this is the most incredible procedural sims I have ever seen. Beautiful. Really stunning work.

[@DanimoDev]

Man, this video is gorgeous! Nice work Sebastian!

[@lexsec]

My favorite programmer has uploaded again! :D -kale

[@KentHambrock]

The simulations are all so pretty, I want to use them in a game, but I have no idea what it would be about or how it would work. xD

[@viiizzaalishvili9967]

how is your comment 12 hours ago if it was uploaded now

[@capsey_]

@@viiizzaalishvili9967 i guess Patreon supporters have early access

[@midgetmackenzie]

What about giving the player control of slime parameters to solve problems like resource gathering or network building? In later levels there might be slimes that repel each other (9:57)

[@petersmythe6462]

An RTS based on the slime particles in an environment where resources are controlled by either reaction diffusion or multineighborehood automata. You can place down your own signal trails to guide the slime particles but beware, if an enemy detects your slime trails it will delete them and cause damage to any nearby slime particles of yours.

[@terry2295]

@@petersmythe6462 the idea sounds really fun ngl

[@nielsbishere]

Always interesting to see what topics you cover next

[@seanloughran6714]

Absolutely stunning. Love your work! It also is absolutely amazing on my OLED TV!

[@MinEntropy]

Excited for a new video!

[@devsauce]

These are so cool 🔥

[@diegolondrina7510]

Inspiring as always Sebastian. Amazing.

[@vidstige]

This is insane, love it! Excellent choice of music as well.

[@filipsperl]

this really makes me think about life being an emergent property magnified by natural selection

[@o.s.2056]

Well... Yeah, cuz it is.

[@likun54]

hey this looks so good....will you be making a tutorial on same ? A request. No pressure.

[@SebastianLague]

Hey, happy you like it! I want to make a tutorial on the slime simulation, but one issue is that the shader code I wrote doesn't seem to run on some machines. I'd ideally like to figure out what's going on there first so I don't teach something wrong.

[@inv41id]

@@SebastianLague oh yeah, some graphics card vendors don't perfectly follow specification in their OpenGL implementations so you need to be able to test on multiple machines to see that you don't accidentally end up writing vendor specific code. I've particularly had small issues with nVidia

[@belmintuzlic219]

Man it's not just incredible coding skills you have... Your other interests in life, your understanding of the world around you... Every video another story, you are such an inspiration to many people. I wish you everything best!

[@outercloud]

Absolutely incredible and cinematic! I love it! Keep up the good work!

[@tsumurireallll]

2:07 zaaaankoooku... I can't be the only one

[@SmellyNutz]

Ah yes; The man with the nice accent is back PS Sebastien; can you make some coding tuts as well? A request. But no pressure

[@eggpoison5182]

Your videos are so high quality! Great work!

[@Stonium]

You actually took the time to sync the music with the video. Much appreciated - thank you!

[@briangallagher3619]

So for the price of about 2 coffees a month you're just going to provide all the source code for this and all previous projects? I feel like I'm cheating. It would be interesting to tweak these to be deterministic, like make the random number generator pseudo-random and use a seed for a specific sequence, and an overall seed that includes all the variables. Then if you come across a cool one you could just share the seed number.

[@Alzurana]

Check out the video he linked where he goes into more depth about slime molds and ants. He's explaining the random number generator. It's actually just a simple hash function and if you base it on pixel coordinates it becomes deterministic. You can also just store the parameters in a simple base64 string if you so fancy and get a seed that way. The only problem I see is the execution order of thread groups on the compute shaders. I worked with slime mold myself after seeing his video and the reason why results don't perfectly match up between runs is because you can't control when which pixel will be written to. If you use a single texture to represent the field you'll get randomness introduced through that. That's usually not a big issue but if you want to make that deterministic too all you need to do is use double buffering for the texture that represents the "world" so to speak.

[@SebastianLague]

Hey, the reaction-diffusion and cellular automata sims are already deterministic so I could definitely set something like that up if there's some interest in exploring and sharing results! As Alzurana said, the slime one is not deterministic currently, but should be fairly easy to make it so.

[@notanengineer]

Never clicked so fast 😂

[@sdoregor]

Your work is so impressive. Love it!

[@christiangassner1231]

This is beatiful! Amazing work!

[@MattiaConti]

My girlfriend is kind of the opposite: complex rules for very simple daily task

[@alex-greeck]

I'm sure that when nature created this world, her first attempts somehow looked like this

[@Madbird95]

Thanks for sharing! I love that slime mold simulation.

[@mattiasselin4955]

I don't know if you realise this, but this is art. Put these simulations up continously running on screens in a gallery and people will LOVE it

[@ryanreed4698]

Honestly one of the most beautiful things I've seen, and something that carries a lot when it comes to the philosophy of life, and how impossible simple rules could orchestrate such mesmerizing outcomes.

[@kierand8167]

This is stunning, very much enjoyed!

[@TheColorman]

These simulations look really cool. It's fascinating how such simple rules can create such complex systems.

[@PunmasterSTP]

I really have no words for how beautiful this is, and I'm very glad you made this video so that I could stumble across it today! On a side note, the part around 3:53 made me think of microtubules organizing inside of cells...

[@schwons3703]

Truly amazing! Keep up the good work!

[@claudiusgruner92]

1:31 you made a liver!! Amazing video as always.

[@marthinus.x]

Absolutely amazing, thank you so much for sharing these!

[@Tondadrd]

Really great! I also like how the visuals and audio are linked. As if one without the other wouldn't make the complete picture. Reminds me of MelodySheep.

[@alexu.9294]

Man, i love your vids. Every single time a new video shows up on your channel I'm getting exited... just to get my mind blown.

[@tobihendrix1324]

Dude i were on your Channel literaly 10 Minutes before you uploaded this Video because i wanted to know if i missed something new. Glad that you noticed it and uploaded a new video :)

[@kseniia7494]

The best video I've ever seen!❤️ Perfect music, Perfect dimulation. Incredibly accurately it conveys all the beauty❤️

[@Gorgious]

That was quite the journey... Thanks for sharing !

[@arthurcheek5634]

its amazing how organic these are, Amazing stuff!

[@Vantivify]

This was a pleasure to watch

[@pauldhankin]

Nice work combining the music with the visuals!

[@elliot6758]

thank you for sharing these fascinating works

[@LostLargeCats]

This is amazing. Great work!

[@jonathanlorenz-indiedev]

This channel went from coding experiment to just pure art. Thank you!

[@Spar3Tim3r]

I get so excited when I see that you've posted. FEED MY BRAIN

[@christiantoft]

Absolutely awesome and inspiring! Thanks for sharing 🙏

[@rgkm9356]

Glad to see the development of cellular-level simulation on your planet explorer is coming well!

[@TheSlowGrowth]

Oh, these should be available as screensavers! So beautiful!

[@spencerstandish9095]

Don't want to lead down another rabbit hole but allot of these remind me of similar results created using video feedback. know there has been paper and research on the topic but have never seen those results replicated digitally. love your work

[@ravrath92]

Man, I am trying right now to implement a Kinetic Monte Carlo algorithm for a complex system of many chemical reaction and your video shows up ahaha I am always so glad to be entertained by your work, amazing and inspiring as usual. It's so fascinating that morphogenesis produce its complicated patterns the way you have shown.

[@TitanLordofPizza]

Honestly I kinda just want to watch like a hour of this. It is relaxing to look at and has nice music.