How Games Fake Water

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Many Acerola viewers ask the question: How do games render water? Well, real time water rendering might sound intimidating, but it turns out most video games (Final Fantasy XVI, Elden Ring, Genshin Impact, etc.) use a relatively simple technique. How convenient!
Topics covered include: Intuitive sine waves, the sum of sines, vertex shaders, fragment shaders, central difference normals, calculating normals with partial derivatives, lambert's cosine law (lambertian diffuse), blinn phong specular, why gerstner waves are cringe, euler waves, fractional brownian motion, fresnel reflectance, cubemaps
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Code: github.com/GarrettGunnell/Water
References:
developer.nvidia.com/gpugems/...
iquilezles.org/articles/fbm/
www.shadertoy.com/view/MdXyzX
filmicworlds.com/blog/everythi...
Music:
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A New Frontier - VA-11 Hall-A OST
Midori Eyes - Paradise Killer OST
GO!GO!STYLE - Paradise Killer OST
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Thanks for watching!
arrow in thumbnail drawn by thlurp
This video is dedicated to my friend, Alotryx.
#acerola #graphics #gamedev #unity3d #graphics #shaders

[@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

[@bloom945]

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

[@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.

[@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...

[@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

[@user-kx8pu6ys5i]

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

[@partlyblue]

​@@user-kx8pu6ys5iLook at me, son. It's not your fault.

[@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

[@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 😅

[@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.

[@MidnighterClub]

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

[@machaoverlord5925]

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

[@joaoguerreiro9403]

I would say a computer scientist hahaha

[@machaoverlord5925]

@@joaoguerreiro9403 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

[@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!

[@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)

[@crancpiti]

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

[@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.

[@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

[@pyrus2814]

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

[@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!

[@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

[@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.

[@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

[@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 :)

[@sousoulefou]

Always interesting. Love the editing, as always 😂 Keep it up!

[@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!

[@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!

[@syaoranli7869]

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

[@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...

[@Dominik-K]

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

[@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

[@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.

[@bobozeehax]

Heyy thanks for another informative video! You rock, Acerola! :)

[@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.

[@Ithenos]

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

[@KoshakiDev]

Phenomenal video, Acerola!

[@voon7820]

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

[@doce3609]

It is always nice when a new Acreola Video rolls out

[@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 👍🏻

[@DeanEdis]

One of the best explanations I’ve ever seen. Thanks!

[@alan_5127]

Its always a great day when i see you upload! great vid as always

[@ucru]

This was wonderful!

[@BakeBakePi]

That's so interesting! Great explanation!

[@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

[@VesselEngineer]

That video made my life way easier, thanks mate!

[@coorie]

Great video! Excited for more water stuff next time.

[@bytezero3818]

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

[@xadxtya]

I really like how you explain things, thank you

[@Povilaz]

Looks awesome!

[@DurmanHimself]

Love your videos. Hope you get to 100k soon.

[@ZTimeGamingYT]

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

[@ardyolt9788]

Amazing work!

[@PhilSamoylov]

Trove of invaluable tricks as always! Thanks!

[@Acerola_t]

Thank you so much!!

[@funx24X7]

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

[@bastian3461]

would love to see that more complicated wave motion 🕵

[@hungryporpoise5940]

Holy moly it’s another acerola video it truly is a wonderful day

[@therealyojames]

Bro these videos are amazing where have you been in my yt feed all this time

[@cupofdirtfordinner]

great stuff, aced roller 👍

[@DarkSwordsman]

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

[@akkihole_]

I love this channel so much

[@H0mework]

I LOVE YOUR VIDEOS THANKS!

[@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

[@MrMolian]

You got yourself a new suscriber ! Everything was clear and explained in a fun way, keep going 😁

[@jm-alan]

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

[@leonstansfield]

New favourite acerola video. One day I will be epic like you!

[@timowagner1329]

I have been excited for this video. As requested.

[@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

[@VetNovice]

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

[@mrbonono2951]

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

[@lucanapora4016]

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

[@rodslay]

Such a well made video! Keep up with the great content.

[@itso6778]

YTES IVE BEEN WAITYING FOR THIS SO MUCH YES YESSSSSS

[@samuelazeredoo]

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

[@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

[@Matyanson]

Nice collection!

[@lunaumbra5179]

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

[@skoovee]

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

[@blackedoutk]

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

[@Cherry-da-bomb]

yay new acerola video :)

[@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

[@amaryllis0]

Really cool video! Only time I've done a realistic water shader is following Sebastian Lague's planet projects, using wave patterned normal maps

[@nicj_art]

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

[@puddle.studios]

its always a great day when acerola posts

[@PG13park]

I love the “like next video” at the end

[@saikousocial]

Another classic areola banger.

[@itscarli3411]

i love your editing so much you dont understand

[@bots_op]

I LOVE ALL OF YOUR VIDEOS

[@MCSteve_]

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

[@volkoivan]

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

[@adelAKAdude]

Wow fresnel ... You got me there acerola ... What an enjoyable video ... Thanks a bunch

[@blaz7678]

Thank you for this video :)

[@vicentetarabelli]

This is just what I needed for my RTS, only don't need the render, just the waves. It's an aether map, some gameplay stuff, so I'll need to figure out how to get back the data to the cpu eventually. Thank you very mucho!!

[@crckrbrrs]

first off. amazing video as always, goes without saying since your quality is literally unmatched not only in the graphics rendering space but across youtube as a whole secondly, your hair looks great

[@TennessineGD]

definitely my favorite video of yours

[@mayank2564]

great vid bro

[@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.

[@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

[@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)

[@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!

[@uwunora]

thank GOD someone finally spoke up against screenspaced reflections

[@filiformis]

I look forward to more videos on water.

[@rafertysullivan6085]

new acerola vid = good day

[@donatoclemente4421]

Awesome stuff! 🎉