How Games Fake Water

[@Acerola_t]

Get a free 30 day trial and 20% off an annual plan at brilliant.org/acerola #ad Hope you like the video!!

[@k_otey]

nice

[@syaoranli7869]

have you considered Tessendorf's model for Fluid Sims?

[@clarkey8598]

you said it was free!

[@C0nejin]

Nice haircut 👍

[@PlanetComputer]

swagilicious man

[@rafaelbordoni516]

16:32 once I was trying to make the surface ripples of water running in a direction like a stream, and one of my attempts had small ripples that were just moving along the surface without any disturbance and I thought it was unrealistic and added some noise to it, then I saw water running down the street in the rain and it had super static unchanging ripples running along the surface, I felt really stupid

[@Litl_Skitl]

Laminar flow babyyyyyy

[@Solutra]

@@Litl_Skitl that isn't what laminar flow is but ok

[@simonfrancis110]

@@Solutrait is

[@Solutra]

@@simonfrancis110 captain dissolution has done an entire video on laminar flow, watch that before you say anything else

[@Litl_Skitl]

@@Solutra Sorry I thought you meant ripples that stayed perfectly in place. I need to read more carefully...

[@gustavosantos106]

I've worked as a fisherman for a decade. A lot of that time was spent watching the sea and thinking 'there must be a logarithmic mixture to reproduce this effect'. Here comes Acerola to crown himself again.

[@justinblin]

The man himself has come to bring us another well explained video about complex topics I will forget as soon as I try to do it myself

[@compilererror2836]

this is the most accurate comment ever

[@bloom945]

this isnt just how to make water, this is a crash course in graphics programming

[@MidnighterClub]

GPU Gems that are explained simply could be a whole series. You should do more of these.

[@neonfoxgamer-9738]

I swear to god staring at a thing in reality, questioning whether or not I would consider it realistic if it was presented in a video game is too relatable you explained a few concepts in this video that I took like, 2 years to figure out on my own, damn you! (but thanks for sharing it for others) now I can finally point people to a specific good video when they ask for shader knowledge

[@nuvuv1]

i literally do this all the time lol. when he mentioned it in the video, i let out a sigh of relief that im not the only one who does this 😅

[@GRAVENAP]

Nobody does it like you. Explained well, entertaining, thorough, explained performance pitfalls and how to solve them, etc. Your work is a goldmine. Thank you!

[@idrios]

On shadertoy there's a shader called "Seascape". Even with the source code right in front of me, I've never been able to understand it. This was a phenomenal explanation and I feel like I actually understand it now.

[@LighthoofDryden]

BABE WAKE UP-

[@UliTroyo]

Poor babe. Who can catch a nap in this house?

[@noobissk3001]

It's a new acerola video!!

[@naiknaik8812]

babe, babe please why aren't you waking up

[@kkTeaz]

It was 3 years ago, ​@@naiknaik8812 it wasn't your fault...

[@partlyblue]

​@@kkTeazLook at me, son. It's not your fault.

[@seedmole]

I spent all day making structs do what I want them to do in my midi sequencer. This is what I needed to unwind. Hell yeah, that was some comfy overlap between audio and graphics. So many topics that are extremely familiar to someone who has spent more time with synthesizers than with code. Ultimately it all comes back to the Fourier transform when doing things involving sums of sines. Also one thing used in audio design to reduce noticeable beating (i.e. the audio analogy of tiling) is to vary each oscillator independently as a function of time. Plenty of ways to solve that issue but that's the one that immediately comes to mind for me.

[@Acerola_t]

it's all waves all the way down! (also that sounds like a good idea)

[@machaoverlord5925]

basically becoming game dev also means becoming mathematician for that juicy wet water

[@ai_outline]

I would say a computer scientist hahaha

[@machaoverlord5925]

@@ai_outline i mean you gotta sacrifice one or two braincells to fry to create this magnificent juicy water. Not as Avatar 2 level of water but convincing splashy water.

[@machaoverlord5925]

@eveningcommenter6312 i would love that on vr

[@DarkSwordsman]

I am constantly amazed at your ability to make complex topics easy to understand and fun to watch. As an aspiring game dev and current 3D artist, thank you.

[@crancpiti]

I'm looking forward to the next video. The waves in Sea of Thieves look so impressive, they even have physics!

[@nk361]

Yes! I have been hoping for a good detailed video about FFT and iFFT realistic water. I would still like one on that spooky partial differential equation one too, but I know that it's got hands

[@Kaboom1212Gaming]

Something to mention with Sea of Thieves, you actually can see the repetition in the water from high viewing angles i.e. climbing a mountain. It is just very expertly hidden behind all of their other fancy work.

[@Acerola_t]

yeah this is cause the fft approach is too expensive to compute in the shader so it's instead computed into a texture that tiles, otherwise there wouldn't be repetition.

[@Kaboom1212Gaming]

​@@Acerola_t That makes a fair amount of sense. It's still something I'm really interested in learning as well. Most of my stuff is done using textures too to be fair, though lately I've been baking heightmap and other data out of Houdini water sims to get an actual simulation as the baseline and then work with everything outside of that. Have you also seen their big talk about their cloud rendering system? It's quite an approach they use, they gave a whole breakdown at GDC 2019 called Sea of Thieves: Tech Art and Shader Development. I think it might be worth looking at as an approach as well for your other videos coming up, since you mentioned you were getting into cloud rendering as a subject soon too (iirc in your CS2 smoke grenade video)

[@merlang7]

water is one of my favorite topics when it comes to computer graphics because there's so many ways to go about implementing it. my personal favorite video game water is Mario Galaxy, because it feels really stylized and unique, without resorting to solid colors and repetitive textures like a lot of other examples for stylized water. The toxic waste in Portal 2 also looks really nice, despite basically being brown sludge.

[@pyrus2814]

Watching this at 0.25x speed to offset the goober who watched at 2x speed. Gotta internalize every detail.

[@borgking620]

Awesome video, I learned a lot! Still two minor corrections/annotations: 1) frequency is not 2/wavelength, but 1/wavelength. Probably that mistake somehow slipped in with the graph at 1:46. You can see there that you are not showing sin(x) but sin(PI*x). The natural wavelength of a sinewave is 2*PI, also known as a radian. Basically this is an angle-measurement that is based upon the arclength (= traversing the surface) of a circle with the radius of one. 2) the Blinn-Phong model is NOT in any way the basis for PBR. Blinn-Phong is an approximation on the basis on artistic criteria, calculated purely for verisimilitude, not realism. PBR models on the other hand approach the calculations on the basis of physical values. For example a light in Blinn-Phong can be brighter going out than it goes in since it is added once in the diffuse and a second time in the specular breaking energy conservation. A PBR model on the other hand only distributes the total amount of light into reflection and absorbtion, so it can never be brighter than it goes in. Oh and I didn't expect you to be this young, with the quality of your videos and complexity of the topics discussed I expected you to be an industry veteran for at least a few years!

[@Acerola_t]

1) gpu gems is wrong then idk 2) I added an annotation saying blinn phong is no longer considered pbr by today's standards

[@LiveWire937]

Acerola, you're a lifesaver. You just saved the surfing mechanic I was thinking about scrapping because until now my waves looked like an unyielding herd of gelatinous migratory hillocks. still gotta work out a more performant way to make the big waves that crash and go tubular etc., but at least now it feels like I'm on the ocean, and not lost in some sort of undulating mound dimension.

[@Acerola_t]

this method I still think looks yucky for bigger waves, it looks really nice for slower water/stillwater distortion on reflections. Next vid will go over the logic behind the nice realistic big waves though!

[@a52productions]

I'm a physics student going into grad school, and I'm planning on working on real time fluid simulations! It's fascinating seeing it from a nonphysical, more approximate perspective. Of course Fourier series would make their appearance! The domain warping aspect is very fascinating! I would never have thought of that, but it works perfectly. It also seems to naturally result in the low regions being flat and low detail, and the high regions being spiky and high detail. That's so cool! It's also fascinating learning about all this optics stuff. That's the one bit of physics I never got. I suppose if I want to work on games (a hobby of mine) I'll have to learn it some day...

[@real_vardan]

You explain those topics better than my professor, it's hard for me to understand certain equations without having an intuitive grasp about it. Your visualization really helps!

[@skoovee]

“wow frass nal!” was far more funny than it should have been

[@chakra6666]

It's cool to see a breakdown of how stuff usually works, but it's much rarer to see any content explaining 'better' options. Excited for the next video :)

[@patyna4775]

21:26 I'm sorry to say this, but with this rendering time you brought up a great Polish meme

[@BluesM18A1]

the physics of how objects interact with the water and disrupt the usual wave patterns is something I always wanted to learn. Any modern game with seafaring in it would feel incomplete without it

[@funx24X7]

Totally agree about screen space reflections, they're like ants: once you notice them you see them everywhere and it totally ruins immersion.

[@Nuttygamer27]

your honestly one of the game dev people that I like to watch I find it more better of someone explaining me how it's done than someone just tell me how to make it and just coping the code without no knowledge of how it's done, and you're more entertaining to watch than a 2 hour video of someone explaining it like you video are more faster but not to fast to were I don't understand and can't follow along

[@gamingtoday1418]

19:20 I cant believe Acerola forgot to mention the 4th forbidden reflection technique of just using a 2nd camera to render the reflections

[@Acerola_t]

basically the cubemap approach

[@jbritain]

You and Sebastian Lague have made me realise I want to be a graphics programmer, and I thank you for that.

[@raiton99]

THIS! This field is so interesting!

[@Toesty5]

Good luck!! You can do it!

[@SpringySpring04]

Acerola and Sebastian Lague collab when?! I also really like Sebastian's work. I remember obsessing over ant simulations about 2 years ago when I saw his ant/slime simulation videos! lol

[@ZTimeGamingYT]

Trigonometry and fluidity are two topics I would have never have guessed would apply in graphics together. Now, it makes sense!

[@DarkSwordsman]

20:13 LITERALLY ME AFTER I LEARNED ABOUT HOW POWERFUL FRESNEL IS

[@volkoivan]

It's such a pleasure to watch an ugly looking plane of sine waves slowly but surely becoming a masterpiece

[@RoySATX]

Dude, I'd be lying if I said I learned or comprehended much of what you just did, I'll be sixty next year and my short-term memory is, what was I saying? What I can say truthfully is I was able to follow along with you the whole video, you didn't lose me, my eyes didn't glaze over, and my mind didn't drift off. That's good, you have a knack for this! I wish you had been around when I was in high school, I'd have learned a lot more math and enjoyed math a lot more instead of dreading it out of fear I'd become a CPA..

[@samuelazeredoo]

I finally found a use for all the knowledge obtained from calculus classes: being able to understand Acerola's videos

[@rafaeltota]

Every other Ace video I go like that "Oh" gif, starring Chi McBride No better way to convey how this feller here makes me understand stuff that hadn't really sunk in

[@TeslaPixel]

I really hope you get around to the more advanced wave methods. The result at the end of this video looks great but sea of thieves' waves are something else.

[@sumdude5172]

sea of thieves waves take up half the screen 80% of the time. You bet your ass they have teams of dedicated, nda-locked programmers and artists, who are as smart and hard-working as, if not more than, a single sleep-deprived youtuber, focused solely on the water.

[@TeslaPixel]

@@sumdude5172 And this prevents a high level exploration of some of the methods how?

[@Acerola_t]

give me 2 weeks idk

[@someloser7991]

@@Acerola_t 2 months it is, got it 👍

[@0osk]

@@sumdude5172 They did a siggraph talk in 2018 going over it. The talk was called "The Technical Art of Sea of Thieves," it's on youtube. I'm not a developer so maybe they left out some important details, but it seems pretty complete from what I can tell.

[@Yukiixs]

I liked the fact that you chose something else than gerstner waves, which is commonly accepted for being the go-to for waves simulations, you explained why and proved that you could still have good looking water without that much complexity…

[@Wishbone_Games]

Im just sitting here nodding at the screen as if i have any idea of whats going on, loved the video btw

[@LukeFlavel]

Ever since I started watching your videos, I've been looking at real objects and thinking about the way it could be modelled digitally. Water has been the primary object of my attention, so I was ecstatic to see an Acerola water shader video! Thank you so much and I'm looking forward to more water shading stuff in the future :D

[@nicjolas]

IM SO HAPPY you have so many monogatari figures. bro thats my favorite anime of all time. bro just HAD to show them all off

[@RayDimn]

I started my college degree of computer science in the beginning of this year, and even though my primary objective is not to become a graphics designer and also because i am still a noob when it comes to programing and everything, your videos still are always really amazing, informative and fun to watch. Ngl, you are even better to explain somethings than my teachers are lol, hope you grow even more here on KZbin you deserve it

[@Acerola_t]

Have fun! also graphics designers make logos not video game graphics, important distinction!

[@RayDimn]

@@Acerola_t noted 👍🏻

[@Peterscraps]

Screen space reflections still beat cube maps but are less consistent, I like valves idea of using both screen space reflections and cube maps, mixing methods. If an improvement leads to predictable edge cases, plug the gap with old faithful.

[@0xC272]

Love the videos, mad props. One thing I do wish though is that we didn't get a 101 to graphics programming (what a normal is, what diffuse/specular are) in each video. Perhaps just refer people back to an earlier one? I know it's a difficult balance to strike to adjust it correctly for the target audience. Keep up the awesome videos!

[@Acerola_t]

I'd rather each of my vids be a complete package

[@bastian3461]

would love to see that more complicated wave motion 🕵

[@lucanapora4016]

This dude is actually the goat! What a generous man to be spend his free time doing this for us

[@jm-alan]

The replay stats on various parts of this video are gonna go crazy and I love it

[@torphedo6286]

Nice video! This helped a lot in my understanding of lighting, other explanations I saw were really dry and didn't explain the math very well. You should also cover distortion textures! By abusing distortion and multiple scrolling textures, you can make most visible tiling go away. There's a great video by a channel named Jasper about how they used this for water in Mario Galaxy 2.

[@px64]

Very well explained and I learned a lot. I think its okay to not show something on screen for every noun and verb. Sometimes it felt excessive.

[@joshuacampbell17]

9:59 shoutout the Professor

[@sleepyghostmp3]

Just wanna say that Hard to Explain by the Strokes is one of my favorite songs ever, thank u for that reference/reminder

[@Acerola_t]

they played it live when i saw them it was so good!

[@sleepyghostmp3]

@@Acerola_t That's awesome

[@DamianReloaded]

The algorithm seems to have picked on me talking about caustics and reccomended me "VFX Artist Explains the HARDEST Visual Effect to Make" from corridor crew. I wouldn't mind at all a third video in this series about caustics to tight the knot.

[@bytezero3818]

Holy shit, the amount of information is incredible, also i love how you actually manage to keep my adhs-ruined attention span

[@lunaumbra5179]

As a UI programmer your videos have helped me understand more about graphics than any other. Well done chap

[@idedary]

Sine wave and all periodic stuff is extremely useful in a wide variety of applications, even if they are just a bit related to math. I always laugh when I see people make the classic "Another day without cosine" joke.

[@choud-cc]

I’ve worked with gerstner waves quite a bit and I’ve only ever noticed issues with waves curling in on themselves if you add a wave to the mix with parameters higher than the one that came before it. I’d be interested in seeing you talk more about gerstner waves or explain a bit more why you don’t like them!

[@Acerola_t]

tbh the real reason I dont like them is it heavily complicates the partial derivatives due to the horizontal displacement and I found that the e^sin(x) waves looked great anyways for less effort (mentally and computationally)

[@choud-cc]

@@Acerola_t I can agree with that. They certainly add way more complexity than needed for some water use cases. I already find derivatives annoying and adding the non linear, multi dimensional nature of gerstner waves to the equation is a bit much lol Much love can’t wait to see what you upload next!

[@voon7820]

Wow, expertly breakdown the details to the most basic component. Great video!

[@ivankonishi7979]

Just wanna point out that the background tracks are gold

[@1ogic948]

I audibly cheered at the introduction of calculus in this video.

[@ryanhamstra49]

Timberborn has some pretty interesting fluid sims. It’s a semi minecraftian game in that the world and landscape is made of blocks, but the water actually flows and fills the world, as well as having levels at up to 0.01 of a block height, having waves, and even being used up by plants in the area.

[@Agent9]

After the opening of this video and seeing all the monogatari figures, I can finally understand why your title screens always remind me of that show! It was inspired by it!

[@SillyOrb]

First and foremost: Beautiful results, excellent in-depth info, very entertaining and funny. Acerola continues to be one of the best graphics programming edutainment channels I know on YT. Looking forward to the follow-up video, but no pressure. We should be thankful to get these, so I am now considering signing up for Patreon, if there isn't a better (more direct) way to support these accessible, relevant and honestly simply good videos. On topic: A few years ago I created an ocean system for a game that was featuring a lot of water, both visually and mechanically. As pointed out, that Gerstner waves aren't that easy to control and that is a very good point and the reason I chose to not use them. If you need a lot of game design control over water, I found that simple and small look-up textures did the trick. Artists set up simple animation curves in the editor along with additional parameters (calm vs. stormy water looks very different, so you want different contributions from different frequency bands), which were then baked on start-up and evaluated in simulation steps on the CPU and GPU respectively. So, artists could shape waves to look like Gerstner or any other type of non-overlapping wave. They could also have multiple peaks at different heights etc. Amplitudes were controllable locally, as it was just another runtime simulation parameter, so it was easier to control the chaotic patterns when the situation demanded it. You don't want players to be frustrated, because they got unlucky with an extreme trough and couldn't reach a safe spot in time. The solution was very fast on last generation hardware and its synchronous but independent implementation meant that no data beyond basic control parameters needed to be transferred between processors. The GPU computed a height map (there was more than just waves that shaped the water) for rendering and the CPU simply computed samples on demand when queried by gameplay systems, so no height map was required (we also had orders of magnitude fewer queries than the sample count required to compute such a map).

[@dotdotmod]

The Junes music genuinely makes sponsors fun to listen to

[@xanderlinhares]

100% agree with the sentiment about SSR (and shadows). The attitude toward motion blur seems like a trendy thing that people think they shouldn't like.

[@Acerola_t]

I think motion blur on basic camera movement is kinda yucky, it only exists to hide frame rate problems (like in ff16 if you disable the motion blur the low fps is way more obvious) but fast movement effects like a blink/dash arent nearly as impactful without motion blur (e.g. dishonored).

[@gfhfhgfhfgh1562]

I don't understand the fancy letters and maths but it's close enough to a monogatari episode for me to watch

[@ezekiasound]

love the monogatori references

[@PG13park]

I love the “like next video” at the end

[@shadow_blader192]

Now you need to turn it to the wine.

[@MCSteve_]

man has like all the exhibition figures, mad great video as always

[@Dominik-K]

Love the video, great topic. Would love to see more water and PBR rendering topics

[@blackedoutk]

Man, wish I could make videos this entertaining. Is it just a special gift you have? Really cool

[@VetNovice]

Nice haircut, just as fresh as your water. Those specular highlights.

[@NunSuperior]

Sea of Thieves and Assassin's Creed 4 : The Pirate One both have amaaaazing water.

[@Acerola_t]

they both use the same technique!

[@salatwehr4099]

aaah now i understand why there are normal maps and specular maps in my skyrim modding textures

[@mrbonono2951]

A video on fast Fourier transform would be awesome. Thanks for another amazing video acerola!

[@_rogolop]

Some beautiful subsurface scattering will probably bring this closer to sea of thieves in close range than solving the periodicity problem

[@thejinxedartist]

I do like this implementation of water, it looks quite natural and great at the same time, the approach I generally go for is just to take two noise textures and use procedural sampling so that it doesn't tile but I might start using a similar approach to this in the future. also i got a bit confused because I completely forgot about the water community post and was looking on your GitHub post processing effects for different tonemappers and saw the lens flares so yea lmao, still a great video and very informative

[@Acerola_t]

I tried to implement a decent lens flare for the video but it kinda just looked like shit so I cut it

[@thejinxedartist]

@@Acerola_t yea i was a bit confused lmao, i thought it might have been like an early version or something, still a cool idea though

[@dmnkb]

I really appreciate the quality of content that you produce! I can't remember having ever had such good, yet fun explanation on any topic!

[@freevbucks8019]

14:00 - You also need to sample the collision points at least 3 times to get an accurate surface function for the CPU. It was honestly really simple once I got hang of it.

[@syaoranli7869]

I have been waiting for this video to come out! YEEEESSSSSS Thank you!!!!

[@pelegsap]

Great video, just a small suggestion: when writing named functions in LaTeX (e.g. sin, cos, etc.), use "\[function name](x)" instead of just typing the name (e.g. "\sin(x)" instead of "sin(x)"). That way it won't be italized as in 14:25 (the math jumpscare), and would instead be typeset as a normal text.

[@Acerola_t]

yeah that is the literal one latex visual in which i forgot to use the \text for it, if you look at every single other one in the vid it looks correct lol

[@pelegsap]

@@Acerola_t True! Sorry, didn't notice.

[@doce3609]

It is always nice when a new Acreola Video rolls out

[@GreenClover0]

16:50 thank God it isn't just me that thinks about this! :D

[@JessWLStuart]

Only problem with the sound addition at 21:09 is of surf sounds. When on the ocean, you don't hear waves doing anything but hitting the side of your boat sometimes. Being on a beach sounds like the surf, but being a mile out to sea sounds a lot more quite since there is almost no sound (from water) of waves hitting things. You do hear the wind on when out on the sea, depending on the height of things on your ship.

[@williammanning9323]

Speaking of sine waves, here's a neat graphics curve you can use: `sin(t * pi) ^ 0.15`. It quickly fades in and out at the outer edges near t=0 and t=1 respectively. Although I've seen weird numeric errors where when t=1, the output is not exactly 0.

[@SandroMedia]

Please, give us a video about fourier and wavelet transformers! It's incredible how this approaches mimic the reality and how our brain works!

[@sujalgvs987]

I've been learning opengl recently and i wrote my own code for a wave, but it was just one sine wave, and the vertices were...cubes. And i was computing the position in the cpu. Never thought i should do it in the gpu, that's brilliant. Thanks aceroler

[@az-kalaak6215]

I don't understand more than half of the maths used here, but the visuals looks very cool. if one day i'll transition from my dev field to game dev, your channel will be my main source of information xD

[@Ithenos]

Just wanted to say that I adore your videos. They're wonderful.

[@EdenNeedsAYoutubeHandle]

Acerola: [explaining concepts beyond my pea-brained comprehension] me: yooooo he's saying those words Sho Minamimoto says all the time!

[@xvsholtkamp]

100% agree with your take on screen-space reflections. Amen brother!

[@stradius]

Having watched a lot of your videos back to back, it's pretty apparent how good you've gotten with pacing and delivering just enough information to explain concepts without getting lost in the details. Awesome work as always, looking forward to the next one! You did raise a good question that I've never seen a satisfying answer for: why DO games include a bunch of post-processing effects that a lot of people always turn off? Are those people in the minority? Are the effects often just not done well? Is it mostly for consoles/lower-end hardware where lower framerates need more fancy effects to compensate?

[@Acerola_t]

gamers only notice when they look bad and don't have the knowledge to identify the effect when it looks good

[@wilsonwilson3674]

The madlad casually dropping his entire Monogatari figure collection, based as hell.

[@TNTCProject]

When you complained about SSR, you immediately gained a new sub!

[@foodforfaeries]

Fucking it's 1am you hit me with the farquad white while I'm just trying to fall asleep by learning about complex programming solutions

[@DowzerWTP72]

Not that I wasn't already enjoying the video, but your Phase/Faze joke at 2:27 earned the like from me 😅😂

[@ibotje1]

I really hope you'll teach us a little bit about the system sea of thieves uses. since i'm very curious to find out how they achieved such good looking water. And you have a great way of explaining these concepts and formulas, as well as visualizing every step to make it easy to follow for people who lack Graphics programming skills.

[@wacawaca1183]

I remember a moment when i first played NFS Porsche and thought to myself that there wont be more realistic graphics on the time of my life. And then Morrowind come out

[@Acerola_t]

me playing kingdom hearts at 5 years old: wow this is the best a video game is going to look ever

[@icesentry]

Are you planning on covering refractions and depth effect in a future video? It would be really nice followup

[@Acerola_t]

in an ideal world i will inevitably cover every topic ever but whether that's within your preferred range of time is another thing

[@icesentry]

@@Acerola_t lol, yeah that's fair. Depth based stuff is pretty easy, but refraction would definitely take a while.

[@GKinWor]

most addicting video edit style known to man