I Tried Recreating Counter Strike 2's Smoke Grenades

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Counter Strike 2 releases soon and it comes with some very innovative smoke grenades! But, how do these smoke grenades work? Why can't anyone properly recreate them? and can I crack the code?
Topics covered include: Frame debugging, voxels, mesh voxelization, flood fill propagation, ray marching, volumetric transmittance, volumetric shadows, worley noise, phase functions, and signed distance functions.
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Code: github.com/GarrettGunnell/CS2...
References:
www.scratchapixel.com/lessons...
bronsonzgeb.com/index.php/202...
advances.realtimerendering.co...
shaderbits.com/blog/creating-...
iquilezles.org/articles/distf...
Music:
During The Test - Persona 3 OST
Afternoon Break - Persona 3 OST
This Mysterious Feeling - Persona 3 OST
Fearful Experience - Persona 3 OST
Just Like This - Persona 3 OST
Soft Oversight - Sonny Boy OST
GO!GO!STYLE - Paradise Killer OST
Midori Eyes - Paradise Killer OST
New Game - World Of Horror OST
Junes Theme - Persona 4 OST
Sandgem Town (Day) - Pokemon Diamond OST
Prof. Omochao - Sonic Adventure 2 OST
In a Moment's Time - Skullgirls OST
Title Theme - Cooking Mama OST
A New Frontier - VA-11 Hall-A OST
Every Day Is Night - VA-11 Hall-A OST
Neon District - VA-11 Hall-A OST
Climactic Reasoning - Danganronpa 2 OST
Thanks for watching!
arrow in thumbnail drawn by thlurp
This video is dedicated to my friend, Alotryx.
#acerola #graphics #gamedev #unity3d #graphics #shaders #counterstrike2

[@Acerola_t]

Get 20% Off + Free International Shipping with promo code ACEROLA at mnscpd.com/acerola ! #ad As I announced at the end of the video, I am now a full time content creator! Expect videos to come out a little bit quicker with higher quality and less compromises on the project itself (I kinda bit off more than I could chew with this video lol). For a more in depth announcement check out my tweet: twitter.com/Acerola_t/status/1657244847068315648 I'll also be starting up a real stream schedule, I really mean it this time! I'll be streaming monday/tuesday/thursday over on twitch (linked in description). I'll be streaming whatever I want so it'll probably be variety with intermittent dev streams when I feel like it. I'd really appreciate it if you stopped by! Twitch partner is pretty much my last goal in life. Thank you so much again for all your support.

[@toolazytobeoriginal4587]

Can you try recreating tears of the kingdom's abilities? Seem like a cool thing to try to figure out

[@DKarkarov]

​@@toolazytobeoriginal4587 he won't cause tears is just havok engine physics. There isn't much to recreate.

[@illegalcoding]

@@MaxIzrin Wdym? what did gilette do lol

[@DonC876]

Always a pleasure watching a new video of yours

[@illegalcoding]

@@MaxIzrin i knew it was gonna be transphobia

[@DFYX]

Some thoughts about the voxel placement: 1. Their examples for enclosed spaces might indicate that they don't limit the flood fill by a radius but by the total number of filled voxels. That would make sense physically since the contents of the grenade expand to a near-constant volume (assuming constant external pressure) 2. Depending on the representation that the physics engine uses (for example bsp or octrees), real time collisions between voxel grids and the environment might not be too expensive. 3. That would make it possible to use smaller local voxel grids around the grenades instead of a global one which saves a lot of memory.

[@Sylvarus]

Realtime collisions are required for CS because there are a few dynamic objects (doors/windows) that can be opened/destroyed.

[@dmitriytuchashvili8594]

​@@Sylvarus I think they might bake the environment in chunks, and the chunks that contain dynamical objects will have several variations corresponding for different states of the objects

[@user-sl6gn1ss8p]

if source 2 is still quake engine under the hood, it might still used baked-in collision hulls, and there's not that much dynamic stuff which might need checking - until I see the smoke interacting with moving doors in interesting ways my bet would be they take the easiest possible way out there : p

[@potatofuryy]

⁠@@user-sl6gn1ss8p Source two doesn’t use collision brushes anymore.

[@Anohaxer]

@@potatofuryy source 2 authoring tools don't use collision brushes anymore. collision brushes are nevertheless very efficient for static geometry, so they might bake all static collisions instead of considering them separate objects where possible.

[@SokoBuilds]

Wow, this took a lot of work.

[@hypegaming5547]

True

[@EvokerKing]

took valve 10 years to make a second csgo, i now see why

[@DebasedAnon]

​@@EvokerKingAll joking aside a lot of people dont comprehend how hard of a tightrope walk remaking CS in a new engine is, any minor screw ups that affect the extremely refined gameplay loop will get more hate than most Triple A devs get for releasing absolute trash. To just make a CS game in source 2 isnt that hard, to make one that keeps the high skill mechanics identical while upgrading everything else and making sure none of it screws with said high skill mechanics thats where the challenge lies. Not to mention they had to make sure it was also extremely optimised and ran on a potato while looking nice.

[@MrSongib]

It is work

[@hackmeister12]

It just works

[@shayes.x]

I know that you are literally a professional at this stuff, but it still breaks my brain that you made all this plus the entire video in like a month or so. Absolutely nuts, makes my week when you drop a new vid!

[@aparato1993]

While working full time!

[@whannabi]

And not putting an ad every 5 minutes like some people do !

[@simoncollins69]

he wasted no time searching for high resolution images for the memes

[@cumibakar10]

He’s far from professional. An amateur hobbyist at best.

[@deemp6773]

@@cumibakar10 you call this amateur?

[@thejinxedartist]

How on earth do you make these videos somewhat educational and engaging at the same time... also casserola lmao

[@TheXientist]

personally i would have coded the smoke to have a set amount of voxels to expand, counting down from the total every time one is placed, completely ignoring the radius. this way you get smoke that entirely fills a corridor that is longer than the free standing smoke radius. though if you do this the elliptical nature of the voxel cloud is lost so valve must be doing something else as well, probably a combination of the two

[@ChrisUG]

you could modify the floodfill algorithm to not expand vertically (making it think its blocked) every x frames which would act as a sort of atmospheric pressure assuming it happens quick enough not to create artefacts. Or put some sort of chance element on vertical expansion

[@Acerola_t]

Yeah the more you try and solve this propagation issue to fill generic volumes the more you approach actual fluid simulation lmao so I kept it simple

[@underdweller]

I'm picking up that the more effort you put towards implementing it the more often you say "what the fuck, valve?"

[@torginus]

I think that (and more) is perfectly feasible if you calculate the voxel fill on the CPU and just upload the thing into a compute buffer. Considering its not a huge amount of data, I think it's perfectly feasible.

[@dthunes]

Why don't you just use horizontal and vertical components for the counting function. Setting the vertical count limit smaller could create the ellipse shape.

[@delayed_control]

6:01 I literally exclaimed "RAY MARCHING" at this exact moment lol. I like how you structure those videos, you don't just deliver information, you make the viewer arrive at the conclusion themselves, that's how you actually teach people stuff.

[@coriumCrush]

every once in a while i am forcefully reminded that the number of operations per second current generation hardware is capable of executing is absolutely fucking bonkers bananas

[@maxinai_]

Just a quick thought on the bullet hole mistery: My first thougth (with the texture and all) was that they might be using a mask. Basically, there is a seperate render buffer that renders two quads with the texture you showed for the entry and exit "hole". These get combined mutiplicatively so you only get a non-zero value if the entry and exit overlap (which means you should be able to see through in a straight line). Then the inverse of that result is used as a mask for the generated smoke texture. This might work... or not, i don't know just my two cents on the topic. P.S.: Great video as always, loved the PsychoPass-Reference.

[@maxinealexander9709]

that's what I thought as well

[@vocassen]

Would be a good idea, but in the video he explicitly said he wanted it to work from multiple perspectives (not sure if that's how it works in CS2). Though I have another idea that would greatly simplify the calculations (and most importantly eliminate multiple checks and sqrts): They could compared each position to be sampled with each ray, with X and Y being the offset in the plane, and Z being the distance along the ray. Then they could sample the texture using X and Y, and compare the sampled value with Z to see if the voxel should be rendered or clipped. This is super simple since the texture sampling can be set up to clamp out-of-bounds samplings, and the texture also provide the hole shape, eliminating the sqrts. So all we would be left with is a few multiplications, two divisions (scaling distance to the texture bounds), a texture sample, and a single comparision with division between sampled value and Z (to check whether the voxel clipped).

[@HionV]

I think that the way that texture works is it is actually just a map that is used to alter the density of voxels that the bullet ray passes through (in screenspace relative to the intersection point with the ray). Purely a speculation on my part though, I only really have a surface level understanding of 3d graphics.

[@nazaxprime]

My favorite mystery I'm the whole puzzle. My story is a modeler told them to subdivide those voxels and they said, how big and how fast is the projectile.

[@nazaxprime]

​@@vocassenpretty much my solution as well, if I'm following you right, though I added a step to animate the effect and increase the granularity of edge activity around the time/speed and space where a projectile would cavitate in line with its bullet physics model on the engine... Cool stuff.

[@eborge9711]

Acerola, could that red hole texture be a parallax effect? They just use it as a mask? That might be doable? If it's skewed at an angle, they probably assume you can't see through the hole anyways, so they just hide the mask all together (due to parallax's weirdness at acute angles?)

[@EmApex]

Would make sense because they use parallax mapping for bullet decals as well, you might be onto something

[@pablodelgado744]

Best point I've seen yet

[@KaletheQuick]

This was my first thought too. Essentially a decal texture that lets you see through the smoke when you are looking at it.

[@NoTengoIdeaGuey]

Yeah i think he gathered that much, he said he was confused specifically about how they use this mask for other players at different viewing angles than the shooter.

[@eborge9711]

@@NoTengoIdeaGuey It should work the same way. If it's flipped 180 degrees, just use the same shader with a flipped direction.

[@nathanh755]

You are serving a niche in the gamedev community that feels halfway between sebastian lague and dani and I love it. Hope to see more soon :)

[@CraftBasti]

I'm a bit disappointed; I was like "who's dani" and thought he'd be the absolut dev professional with knowledge equal to black magic, but realized his contribution in your analogy is the presenting style instead

[@willemowen2515]

My jaw dropped at the ray marching technique, it’s truly unbelievable how clever some of these concepts are.

[@weidiocrow]

I'm astounded by this video. In like half-n-hour you explained 3D coordinate systems, noise, ray marching, several properties of light, BAKING, a fill pattern that's re-usable within the effect, plus five or so other prosperities on top of almost replicating the smoke effect. Pretty amazing you did this in less then a month tbh. 13:00 Now wondering how in the world Teardown's lighting is so good. Since all their level geometry is dynamic, they can't really bake anything right? 🤔

[@heliusuniverse7460]

that's because teardown has no triangles. It's always working with voxels so you don't have to do any conversions

[@dronihack]

I sometimes think he talks too fast to understand everything. But that's alright, if you want you can try to rewatch it bit by bit.

[@vibaj16]

@@heliusuniverse7460 then how does it do dynamic geometry that's not aligned with the voxel grid (and is rotated)?

[@Hexcede]

Teardown uses full fledged raytracing

[@BurningApple]

@@vibaj16 Probably domains.

[@bobthedeleter]

wake up babe new acerola video dropped

[@Turbosquirl]

@@darkxseries7can confirm

[@smilleur]

I downvote this comment every time i see it

[@SirNightmareFuel]

Thanks babe 🚬☺️

[@M.m.nt.m.n.t.m]

He makes me tired

[@banananoodles]

@@SirNightmareFuel I think your holding that cigarette the wrong way

[@jaysonrees738]

Math buffs and programmers must have some form of insanity to think like this. I get what's going on in a simple way, but to keep track of all of these functions and then stick them together in a functional way is simply astounding. What's more is that they've figured out how to make this stuff get calculated quickly. This is why I try to never give game devs crap when they do silly stupid things that break stuff. They've already achieved feats that I can't even begin to touch.

[@XoIoRouge]

Well, to be fair, we didn't figure out how to make this stuff get calculated quickly. That's the GPU and whoever designed that already figured it out for us. We just figure, "Hey, if we do this thing 36000 * 800 times, it'll be slow. Let's try to reduce those numbers." :)

[@TorMatthews]

I wrote some volumetric clouds a awhile back and on the topic of curl noise: consider bitangent noise instead. The main feature you want from curl noise is the zero divergence aspect, and you can get there in two gradients instead of three so it's cheaper if you're generating it in realtime, which is worth doing for your zero-divergence component

[@LiveWire937]

I'm currently ~2 weeks into a psychotic speedrun attempt at teaching myself how to make a halfway decent game from scratch so I can finally properly tell this visual narrative I've been mulling over for a few years, now that the message and themes of it feel super relevant to current events. Still sleep deprived from beating my head against shader code all weekend and been kinda feeling like none of it even really sunk in, but... for the first time, I actually feel like I kinda understood most/all of this. Normally your more technical videos tend to lose me early in, after which I'd only occasionally continue watching for the top notch presentation and entertainment value... guess I have some older videos to re-watch :p

[@SimplyWondering]

howd it go?

[@bots_op]

Maybe the magical bullet hole texture is used to mask out the part where the bullet was shot before it is recomposited back into the main frame

[@Dibblii]

Love the Goodnight Pumpum God reference 3:45

[@mooncatcher_]

I'm not an expert at all, but the bullet holes look like 2d composites on the final alpha matte, and if you move away from the line of the bullet another duplicate of the texture slides to obscure the hole.

[@mooncatcher_]

Should be extremely basic and fast

[@SagnikDasgupta]

This makes sense.

[@Rivandu]

And maybe only visible client side? Haven’t played it, so wouldn’t know..

[@dronihack]

Yes but looking at the footage it seems like it has depth. There is a bit more to that than only masking

[@joelambert7128]

@@Rivandu I don't think it would be wise to leave an effect that could confer a competitive advantage client side.

[@StanleyKubick1]

to someone who dabbles in 3d with some art school skills, the technical knowledge on display is staggering

[@evilotis01]

yeppppppp

[@dinoscheidt]

Lot‘s of respect for how far you go here to make a video. Mad respect.

[@Banaaani]

Damn, this is impressive. The smokes look really good while keeping solid performance.

[@arturoweird9695]

Me: F*king amazed by the work and the results. Acerola OCD: What? Still not enough? Me: I never say that Acerola OCD: Fine I'll simulate how light pass through particles differently

[@EricMBlog]

I do wonder if they have a global voxel grid, or if they make a local one when the grenade deploys. If you included simplified bounding boxes for your environment objects (which they might already have for basic collisions), it seems like the cost of setting it up might low enough.

[@Acerola_t]

I don't believe they do as the number of bound constant buffers doesn't change based on the amount of smoke grenades in the scene

[@zlico1]

i really like your humor, and i love shaders even more when i see your videos.

[@Cash-Trax24]

Could the bullet hole textures Valve used on the smoke have been used as perimeters for real-time textures? Like the flat textures on the portals in Portal made to look like the actual environment through the portal. And each perspective from each player in the lobby could be rendered separately, like the multiplayer in Portal 2. Just a thought.

[@benshulz4179]

I believe that is the case, but this alone doesn't explain the 3d effect. In CS2, when doing the depth testing through a bullet hole, each pixel takes from a seemingly correct position of the noise, creating a proper 3d effect: The smoke inside fades into the surface of the smoke. This leaves me to believe the ENTIRE voxel is ignored when it sees the bullet hole.

[@Cash-Trax24]

Then I'd be led to believe they have some form of client side ray tracing, but I do know how heavy on the hardware that would be.

[@vladislavrys4540]

Obviously the result is astonishing, a lot of work have been put into that! But I really admire the effort your have put into the explanation of the animation parts, that is soooo fascinating to watch... Thank you for that :)

[@ArsArmegis]

I don't get it. I'm stupid.

[@Birchish]

Nah, you aren’t.

[@quinndepatten4442]

No, we're stupid. Apes together strong.

[@geeshta]

It's hard to focus on the video when you use such banger soundtracks from some of my favourite games

[@Acerola_t]

it's to distract from my awfully monotone voice

[@ZettXXII]

Thank you. There's truly nothing quite as satisfying as listening to such a delightful and informative explanation.

[@EsusGamer]

From the looks of it CS2 had a set amount of voxels the smoke grenade will emit and would flood fill to meet this limit.

[@stormy_in_vr640]

this is wildly impressive, I'm so fascinated with game development, and this was a hell of a journey, awesome vid bro!

[@TheDwarvenDefender]

This smoke reminds me very much of the clouds and / or fog seen in Xenoblade Chronicles 2 & 3 and The Legend of Zelda: Tears of the Kingdom. Maybe Monolith Soft, who worked on both games, used a similar technique for nearby fog / clouds in their games.

[@photophone5574]

The smoke looks so realistic in some screenshots. It looks like you went into photoshop and cut out an image of dust, and then you just pasted it into a screenshot of a game.

[@Novacification]

Another small thing about the bullet holes is that they react to the volume of the smoke. You can only create bullet holes near the edges, not in the middle (you might able to with continued shooting in the same place, not sure about that). This was hugely impressive though. Great video!

[@janlohse3130]

I always love seeing your anime and manga references to the Monogatari series, Tatami Galaxy and more. But I really didn't expect a reference to god from Oyasumi Punpun at 3:45. Keep them references coming

[@akuvr]

The quality of this video is insane, super informative and so well structured, the effort you put in really shows!

[@f3rny_66]

this made me realize some extra reason to have smoke as voxels: replays. Being a competitive element, making the smoke visible in replay (and tournament transmissions probably also more important in this day and age) exactly as as played is fundamental

[@spitgorge2021]

man, that bit with you clipping out of the TV during the sponsor was rlly funny. a v small thing since the rest of the video is also wonderful but i especially liked that little joke :)

[@Acerola_t]

thanks it's actually my favorite joke i've put into a vid i think it's really funny

[@Leon3cs]

Your skill to simplify such complex topics is simply amazing, I don't even know how to write shaders and 3d stuff but I love watching your videos

[@crow4277]

acerola you are a legend and one of my favorites youtubers!!!!!!! so happy to hear you are now full time

[@KateVR_Dev]

That's incredible and even more incredible is that you share all of the code

[@ldcent8482]

that va-11 hall-a or whatever it's called banger did not go unnoticed cheers

[@ShortyTwo42]

Congrats on being a full time funny internet man. Your videos are what keeps me inspired in pursuing a career in computer graphics. It's so much fun to watch your content, thank you

[@AkuraTheAwesome]

It'll be interesting to see the bugs we get with CS2's smoke, beyond what people have already tried there isn't much else that will give us so much raw information to speculate over. Keep an eye out for smoke bug videos folks, that's all I'm saying.

[@PauLtus_B]

I remember hearing Breath of the Wild rendering everything under the water surface at half resolution, but it would then later be changed by a displacement map. I think the smoke effect gets away with the low resolution just fine as is, but I wonder if a similar process might still be able to fake extra detail.

[@copperverdigris7321]

I love these videos! Seeing the smoke just getting small little improvements along the way and summing up to something that looks amazing in the end is like a story on it's own!

[@alina_rosa]

I absolutely love the in-depth analysis. But also wanted to give kudos for the bg music selection. It's a nice surprise to hear Va-11 OST

[@CosmicDTaco]

Absolutely amazing explanations and showcase with an appropriate amount of humor. I hope you continue to do what makes you happy and share it with us all!

[@hawns3212]

Very well made video. As a fellow graphics programmer, its nice to see some love for topics like this. Kept me entertained throughout the entire video too. You've earned a sub

[@Vitamin_Games]

Congrats on getting your first sponsor! Was watching you develop this on twitter! Video didn't disappoint!

[@ceilidhDwy]

You are my favorite gamedev youtuber and you actually inspired me to start learning a little bit of gamedev with your grass video (god that grass looks good), so I am very exited that you are going full-time and I hope it works out well for you!

[@SimeonRadivoev]

The bullet mask is probably just projected on the smoke volume from the direction of the bullet. It's just used to subtract density. This should work for all viewers. Imagine a negative projector for the density. Should be easy to give you projected coordinate of a world space point on the bullet mask, and it will form the nice cone. The resolution would be very high as the check can be done in view space not voxel space.

[@benshulz4179]

This prevent bullet interactions from two directions, no? If you shoot from left and someone shoots from right, you wouldn't see the right-left bullet hole inside the front-back bullethole.

[@pixstatic200]

For the bullet holes, I would've just thought they projected the texture through the smoke. Keep track of every bullet hole's location and direction, then when sampling the smoke density you project the point you're sampling onto that plane and sample the texture that way. To make the hole get smaller further from where it was shot, you can offset the vector along which that point is projected. I'm honestly not sure how efficient that is - I'd have to try it - but that was my first thought when I saw how the smoke works in CS2

[@jaktrak]

I have no idea what you are talking about, but I love it so much. It would be cool to understand everything, but I also have fun just looking a the complexity of these examples. Thanks for the awesome videos!

[@wx39]

This is really cool. While I'm not currently doing/learning game development, I love learning about the trucks that developers use to make perfomant and visually pleasing graphics. This is definitely something you excel at teaching and demonstrating at a good level of abstraction. It feels like you know just how much detail you have to share so that your videos are informative and engaging, while introducing topics/techniques that we could go research if we want more detail.

[@BaxDigitalTest]

Idea for the texture they use for the holes. Maybe it is used similar to a volume texture in 3d by just scaling the height of the texture a lot into the volume and then they subtract it from the density. Like a 3d decal. Or they remove the voxels on hitting them. that would work with the grenade explosion aswell.

[@qqii]

Removing voxels would require a very dense voxel grid, far denser than the one shown in the video.

[@tiarkrezar]

@@qqii could work for grenades, but the grid is definitely too coarse for those bullet holes

[@user-sl6gn1ss8p]

@@qqii maybe some displacement magic affecting the neighboring holes deals with that somehow because magic?

[@unfa00]

Maybe it's possible to project the hole's texture in word space and sample these projections during raymarching to influence density of the volume?

[@RedGreene]

Rather than removing the voxels I think the texture is just used to negate the visual effects already induced by the smoke. Like, "if bullet hole texture shows black, do not show smoke effects here". Then fade that mask out over time with some function to give the smoke the appearance of refilling the smoke, when really it was still there the entire time.

[@bibbytenbillion]

you have no idea how much i adore your videos, they have touched on something i've always wanted to know about but didn't know how to find perfectly

[@SamHartwell420]

So excited that you're able to do this full time! Congrats and I'll be watching your career with great interest! Keep up the good work!

[@dimitri0404]

Wouldn't it be possible to deside the shape of the smoke by throwing particles and and then calculating witch voxel a particle is in and then and filling in the voxel. (And I mean throwing like 50 particles not just making particle effect smoke, so not rendering the particles themselves) That way you don't actually have to pre-bake the whole map. It also gives you the posiblility to make the smoke Dender if multiple particles are in the same voxel. You could also only make a voxel grid at the moment the smoke is thrown and only in a certain range of where the smoke lands. And only keep that grid for a the life span of a smoke grenade. That way you minimize the amount of voxels that need to be rendered. You would still have to make sure that shit dousnt break when multiple smoke grenades are thrown.

[@nkkls]

Wow !! A new acerola video !! such amazing

[@Nvargas31]

this is the first video i watch from you, and the references, soundtrack used, editing, and explanation were on point Can't believe i didn't find you earlier

[@farhadaa]

I believe that the smoke hole could be a displacement mask that hides that part of the smoke, much like displacement decals but far more sophisticated, still confusing and amazed how it is done and how you managed to get close to the real thing.

[@haiperbus]

Monogatari intro, I kneel

[@jesco3921]

I was going to give my opinion on how the decal texture might be used but I will instead respect your wishes and keep it to myself. I will also be implementing my idea in my own free time to prove thats how it works. I hope you look forward to it.

[@aboxninja]

ive seen a lot of your videos they are very well made idk why you are so underrated please keep it up

[@s-ata-n]

3:45 mmmmm nice little punpun reference, i liked it very much

[@isaipack]

Didn't watch yet but can say confidently: what a banger

[@MrNatsuDragneel]

I think they use marching cubes, mip map of a only one hole texture setting the angle on creating, and apply based on voxel of entry and position of bullet. After they use the entry and out of bullet to interpolate the animation.

[@Acerola_t]

If it were marching cubes then a mesh of the smoke would be bound to the render pass, but I am always looking for an excuse to use marching cubes

[@benshulz4179]

Incredible video, I will try this out myself, seems fun! Meanwhile, a theory on the bullet holes: When you shoot, it applies the smoke bullet hole decal (and decreases it's size over time) on EVERY voxel on the shot's path, including the voxels inside the smoke. Then, when doing depth test for a pixel, we check if the pixel can see a decal from a voxel. If it can, it ignores that entire voxel for depth testing. So if we see all voxel's decals, we ignore all voxel's depth and see through smoke, in that pixel. But if we see two voxel's decals, we ignore only those two voxels' depth. After applying noise, it should create a proper 3d bullet hole effect. Explosion clearing might be the key here. It could in theory just mark voxels as "do not render" and then apply a smoothed explosion decal on every voxel which is touching those "do not render" voxels, then ignoring entire voxel per-pixel like above if the decal is seen.

[@ethanmitchell505]

Dude I freaking love how you make your videos and your style. You’ve easily become one of my favorite tubers.

[@ian_silent]

Great video! Really impressive stuff. And you explained even the complex stuff in a fun and interesting way.

[@bakerfx4968]

You just keep getting better and better! Keep up the good work dude! Awesome video and execution. In valves implementation, are the bullet holes billboarded to the camera? Could they just be running a simple transparency of the smoke shader with the bullet hole texture? Maybe you were overthinking it

[@icelaenl]

You're so good at explaining this stuff that, armed with nothing but a chemistry degree and a receding grasp of multivariable calculus, I now also feel like I am an expert in video game graphics. Woe upon my friends and family whom I'll be ranting to about all of this to the next time I see smoke in a game.

[@nothinghere1698]

Your videos are always such a joy to watch I feel like I'm on the edge of understanding something then you dash my hopes every time XD I'm binging them at the moment

[@verbatim7488]

This is insanely cool, very informative and super entertaining. Good work

[@progfix]

Looking forward to more videos now that you do this full time! Awesome work!

[@Jejkobbb]

If I were to attempt doing the bullet holes in the smoke myself I would probably create two floating textures (like the ones you found in the game) in the air when the player shoots. One on one side of the smoke and one on the other, then render the floating textures separately. And if the black color of the texture overlaps with the one on the other side it would be used as a mask for the smoke layer. I'm not sure if this would actually work or look good, but that's how I would try it.

[@whidzee]

very cool. I'd love to see you tackle those volumetric clouds in the sky.

[@enoix3683]

I always wondered how these insanely detailed clouds were possible in both horizon games, I'm glad I finally got to hear and see how they did it.

[@RayDimn]

This is my first time watching a video from you and i got to say. THAT WAS AMAZING ! Honestly this was one of the most entertaining, educational and Interesting video that i have watched in a really long time. Seriously really great work whit the video, not only whit all the explanation but also on how entertaining overall you made this video be. Congratulations 👏🏻

[@StackoTra]

you're so underrated, i love watching your vids idk why, and i love the effort you put on editing. keep this up blud!

[@Raphiki77]

Very interesting video, thanks for all this work! The progression of information is very well made, taking the audience to the relevant conclusions instead of simply dumping info

[@ChaonicMew]

Holy shit. I'm high and I just marathon watched Nathan for you. Come for a palette cleanser and you jumpscare me with Nathan in the first few seconds. I can't even.

[@PurpleDaemon_]

Great job. I see many have tried to recreate this effect, but it seems you are the first to achieve a result that is so close to the original solution.

[@Codeer]

Great video! Some really interesting topics and the end result looks awesome!

[@Fishman7523]

Great video! I love how neatly and cleanly everything is described, and especially how well edited the sponsorship and baking segments were. Your videos have so much charm to them! I have a question though. Instead of using a flood fill algorithm, could you instead modify your radius function to consider voxels that are part of an object to be a distance greater than one? To explain, imagine were tracing a straight line from the origin point to the outside of the ellipsoid, but your straight line went through an obstacle. As you were counting voxels from your origin point out to the edge of the ellipsoid, could you make it so that the voxels that make up the object are registered by the function to have a distance greater than one, so that they exceed the radius and therefore, particles of smoke do not generate beyond that? (this is very difficult to explain I am sorry, but here's another approach) imagine you're stepping out one voxel at a time away from the origin. empty voxels count as one step, but a voxel that makes up a wall or another object counts as 100 voxels or something. Your radius is only five steps, so you move out five steps and generate your smoke voxels along that. Every step you take out from the radius you generate voxels of smoke. Step one is empty space, and you've moved a distance of one voxel away from your origin so you generate smoke. Step two is empty space, and you've moved a distance of two voxels away from your origin so you generate smoke. Step three however, brings you into a voxel that is occupied by your wall, and although you've technically only moved three voxels away from your origin, your algorithm considers that you've moved an extra 100 voxels with one step, and that exceeds your radius so you stop generating smoke. I don't know if this would even work, but I thought it was an interesting concept :)

[@Fishman7523]

Actually nevermind your value-based flood fill solution with the wraparound smoke works waaaaay better than my idea. 😅 Maybe mine would work for something that just generates straight lines from it's origin point, but then again there's most likely more simple ways to do that too.

[@Costel9000]

Everything in this video was so over my head, the info might as well have been airplanes in the sky! But really enjoyable and entertaining, so it felt like like an airshow!

[@ImYourBias]

Freaking awesome video. Love how everything is easy to follow regardless of technical understanding.

[@simenstroek7599]

Some thoughts on the bullet hole thing; it doesn't look like Valve does proper shading or "tunneling through" the volume either. I suspect that texture is used to simply mask the entire volume before compositing it into the scene. The "black magic" is only a matter of how to place, blend and track the location and "angle" of the hole particle. Though the holes only last a few frames so it's okay if the solution isn't very precise. This approach wouldn't work for bullet holes that don't closely match the camera perspective - but if you think about it, it doesn't have to since you don't see those anyway.

[@verd7719]

I would love to see more similar stuff like voxel and volumetric fluids. I am quite a starting game dev and a tech enthusiast. I am currently having lot of fun understanding how even the quite complex programing and software works but rendering, especially realtime is something that I cannot find enough good materials, especially some interesting. And your videos are just that, by the way I have bought books from Invidia that you recommended in some older videos and they are really good thanks.

[@Acerola_t]

Thankfully it all kinda works the same for volumetrics, so if you read through the resources I put in the description I think you'll really accelerate towards what you want to do

[@pcvsk8]

Honestly one of my favorite youtube channels. Keep it up!

[@bouncycow3010]

Wow. You have a brilliant way of explaining stuff. Maths is really cool when you use it to solve these sort of graphics puzzles

[@mvstermlnd]

Loved your hard work and your comedy bits, amazing video 🙌

[@hoasd1493]

Phew! Who thought volumetric interactive smoke could be that exhausting. Incredible efforts there Acerola, Thanks for the video :)

[@sanitizer345]

Really well made, informative and entertaining video! Good job and keep it up!

[@MonsterJuiced]

Bro, this is incredible. As an armature myself my solution would have been to use a low res volumetric particle emitter with a set radius and have the particles kill themselves on any collision lmao

[@DoxSteele]

I love that you used Kaiki when representing "lies" got a quick laugh from that

[@Luminoir436]

I watched all of the video without skipping even I don't have any clue what he is taking about. I'm still amazed by ur work