I Tried Recreating Counter Strike 2's Smoke Grenades

[@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.

[@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!

[@w花b]

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?

[@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

[@Hackmeister-TV]

It just works

[@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

[@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.

[@thejinxedartist]

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

[@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

[@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.

[@willemowen2515]

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

[@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

[@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

[@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

[@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.

[@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!

[@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." :)

[@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

[@Dibblii]

Love the Goodnight Pumpum God reference 3:45

[@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?

[@hablo_papøl]

howd it go?

[@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.

[@ZettXXII]

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

[@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

[@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.

[@robotdude4377]

It has been more than 1 year since the upload of the video but no one got "Bake monogatari" until now it seems. With your editing, memes, name of the channel . And with your dedicated shelf, I can say you are an avid fan. How cultured.

[@Acerola_t]

someone finally got it holy shit

[@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

[@DuckPerc]

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

[@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 :)

[@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.

[@Armegis]

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

[@Birchish]

Nah, you aren’t.

[@quinndepatten4442]

No, we're stupid. Apes together strong.

[@iamlosingmysanityrapidly]

Your not, it's just complex

[@Octogenico]

I was gonna leave a support comment but 69 likes

[@someperson9]

Balls get shaved

[@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.

[@SuperNuketown2025]

My guess on the CS2 specific holes is that they’re using some GPU buffer shenanigans, much like the Portals in Portal. How exactly they’d employ this strategy, I couldn’t tell you, but it’s my only good guess here.

[@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!

[@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

[@akuvr]

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

[@MyCarllee]

Just extrude that bullet hole mask along the bullet vector, you get a irregular 3d shape with density. Take that into account when you do raymarching, you get a hole in the volume. It's probably the reason why the hole only appears for a very short time, because the more holes you got, the worse the performance.

[@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.

[@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.

[@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.

[@AlternateAccount-t1j]

this looks closer to cs:go's artstyle than cs2s, and i like that

[@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

[@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

[@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.

[@raphael.e.diener]

Considering high fidelity voxels. It might be worth checking out: "greedy meshing voxels fast: optimism in design" - handmade Seattle 2022

[@KateVR_Dev]

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

[@leinadlink]

Man, your videos really make me want to get back into my IT career to actually learn about math, algorithms and discreet math once again. But then I remember they made us make our calculus exams completely by hand, with no calculators, so I give up.

[@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.

[@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

[@haiperbus]

Monogatari intro, I kneel

[@littlemrh]

I think maybe the bullet hole texture could be a used as a mask that is wrapped around a half sphere very close to the smoke in order to enable it being viewed from all angles

[@StanleyKubick1]

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

[@evilotis01]

yeppppppp

[@NER0IDE]

An idea on how Valve could be creating the holes is by using the bullet hole texture as a mask on the player perspective for the ray-marching to continue through the smoke. The mask is centered on the bullet hole and allows rays from the player perspective to avoid the marching early-stop. The size of the hole could when opening/closing could be the hole texture being scaled up/down using some non-linear function.

[@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.

[@bastian_5975]

For the bullet holes, maybe the texture is used for how much smoke is removed by the bullet hole... I think all you have to do is figure out what part of a rectangular prism the point is in, translate that to the surface of a square that then is used to find the value of the bullet hole at that point, and then multiply or subtract the density you see at that point on the ray by the bullet hole texture at that point. Then you just need to either shrink the prism or change texture based on a timer. I probably have absolutely no idea what I am talking about.

[@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.

[@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

[@crow4277]

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

[@JulianDanzerHAL9001]

it kinda looks like individual voxels are moving in the csgo version so they might be using some system where either voxels atthe edge of the smoke can be squished a bit to have a more precise edge or they're making a small local voxel grid for the grenade that moves in itself and is only as big as the smoke radius

[@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

[@quickscopesheep5994]

Could use sparse octrees to dramatically increase resolution while maintaining performance however that does seem like it would be quite difficult to pull of on the gpu

[@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.

[@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.

[@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.

[@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.

[@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.

[@ivansus_anin1063]

About holes in the smoke. How about trying to use this holes texture as a mask, so smoke isn't rendered where the texture isn't transparent. Then you lock the plane with this texture on it on a cords, where the bullet interacts with smoke with normal normal pointing in direction opposite to shot. And use a timer to adjust the size of a hole

[@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!

[@isaacbunsen5833]

So to do the bullet holes, you might consider a kind of fluid sim where each cell has 1 pressure. This is separate from the propagation distance from 16-0. When you shoot through the smoke it sets the pressure value allong the path of the bullet to 0, and adds a portion of that value to the neighboring cells. Basically you simulate the amount of smoke in each cell and when the amount is greater than 1, it wants to spread to neighboring cells. You would also multiply the sdf by that value I think.

[@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

[@hablo_papøl]

@@Acerola_t its funny

[@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

[@jumpsneak]

The Godot community has been summoned.

[@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.

[@isaipack]

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

[@playonce4186]

very impressive how maths, coding work together to create beautiful visual graphics. Very good job bro I understood how these smokes are made in detail

[@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

[@leonardoraele]

28:32 CS2 uses a parallax effect on decals (several decals on top of each other slightly shifted based on the angle you look at it) to make bullet holes seem 3D. It's probably the same thing on the smoke holes.

[@natayaway]

i think the answer to the bullet hole question is that they have a wholly separate system than the one you made, with a bunch of smoke and mirrors instead of it being straight volumetric rendering. the way that the smoke would intersect and wrap around map geometry would use voxels and similar math as your model, but use a different rendering system. if the voxels they spawned in the devvlog are just particles with a cube mesh in a voxel-like pattern and a world orientation, they can substitute the cube mesh with a typical sprite stack, render it facing client cameras, fill in the gaps with some function that uses actual volumetric clouds that only generates clouds off of a heightmap of existing sprites. raycast intersects sprites, overlay bullet hole texture in a volumetric heightmap at the location of the sprite's equivalent of a face normal, each sprite card in the stack receives decreasingly mipmapped bullet hole texture overlaid onto the height map, volumetric clouds receive a hole as a result because every single card in the sprite stack has the same heightmap adjustment. use the actual cloud to blend edges between sprite card.

[@maki3686]

Grade 11 phys and math coming in clutch to barely understand wtf u r saying

[@BeanMann]

13:49 a good example of what happens with unbaked voxels is teardown, when you disconnect a particularly large object like a building from its foundation all at once, the prevoisly baked voxels start to be affected by the physics engine, the game shits itsself untill the piece settles.

[@toongloong]

This is absolutely amazing work! The time invested, the writing effort, the experiments… genius!

[@yokinman5550]

The presentation is great, just flashing relevant images on the screen makes it really easy to comprehend what's going on. You could probably watch it on 3x speed and still understand.

[@Acerola_t]

it's the jingling keys approach to education also please don't that ruins watch retention lmao

[@borgking620]

Educated guess on the bullet holes: An array of matrices that project the bullethole texture to an orthogonal "tunnel-projection". Sample the texture and mulitply to density. The problem here is of course this would mean one sample/bullet/step. So a few more wild guesses: They reduce the amount of voxels by not having the whole map considered for the live smoke, but only inside the bounds, so they have fewer live-voxels, but can add additional info about bullets saved in there. For example each voxel only contains indices to the 2-4 closest bullets in the array, so only 2-4 texture samples are needed, instead of ~10-50. Also I guess there is some prioritizations, for example preferring bulletholes parallel to the viewdirection before orthogonal ones, or middle lifetime before semi-appearing before disappearing. TLDR: - have dynamic voxels only in a limited area around the grenade - save all bullets in an array - prioritize bullets for each voxel, save the most importent bullets indices inside the voxel - density *= tex2D(_BulletMask, mul(_Bullets[currentVoxel.bullet], samplePosition));

[@borgking620]

Bonus: as you can combine matrices basically for free, just multiply a perspective matrix and you got a bullethole that gets bigger towards the end

[@nonchip]

my guess at the holes is they just project that texture through the volume (along the shot's approximate trajectory from where it entered and exited the smoke volume) and multiply the "rendered density" by the red channel when sampling the "voxels".

[@s-ata-n]

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

[@Emanuel-sla-h5i]

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!

[@kvlvxn6186]

The video was already insane but the Sonny Boy ost at 15:05 is what sold it to me

[@EmilMacko]

Instead of having a voxel grid for the entire map, isn't it easier/cheaper to have each smoke cloud keep track of its own little voxel grid that can change in size as needed by the smoke? Or maybe give this grid a fixed size that is big enough to encompass the full cloud. Naturally these grids would always be aligned with one another, and solving overlaps between two grid's bounding boxes could also be possible. That way you won't need to store cloud voxel data everywhere on the map (even if most of it is just zero, or "clean air")

[@Acerola_t]

This is effectively an equivalent approach with different pros and cons, you could certainly do it this way if you wanted and my demo is not me saying there is only one way to do it.

[@kayvolbeda8669]

For your question about how they did the bullet holes: It seems like a depthtexture/stamp/decal that is placed on the volume's bounds mesh (the two boxes you show at 5:05 ) while its projected along the camera vector through the volume till it hits the end of the volume (the backside). This would be a cheap way where you can sample the normalized depth into the volume and compare that to the depth of that bullethole, if its a higher value then the texture, you just sample 0 for density, otherwise you sample the voxel's value. :) Also on the approach to voxels you described: I think it makes more sense for the voxels to be aligned to the bounds we see at 5:05 again instead of the bounds of the entire playable map. Even at a theoretical 256^3 (akin to a 4K texture at 16.8 million pixels). that wouldnt be practical memory wise (especially given the low target platform of CSGO 2). They may use something like depth cubemap captures or some other approach to querying the environment (Maybe collision meshes as they are pretty cheap? though they mostly live on the CPU not the GPU). All in all great video! love the details you went into to explain the implementation!

[@Acerola_t]

Great idea, but what if you're inside the smoke and the decal is no longer in view?

[@kayvolbeda8669]

@@Acerola_t The decal would be more of a implicit/virtual decal. In shader its placed and oriented on the bounding box mesh face closest to you (akin to splatting it, but more focussed placement where the bullet travels through). The depth at 1 (white) means it's the closest point and the depth at 0 (black) is the furthest point (other side of the bounds mesh). Something like a virtual/Distance field/implicit plane would do the trick and be cheap as well.

[@benshulz4179]

@@kayvolbeda8669 does this create bullet hole interactions? I don't think you can shoot through from two angles and have the carved paths meet.

[@kayvolbeda8669]

​@@benshulz4179 Yeah, you basically do boolean type operation this way. It does become more expensive with more bullet holes though, so you'd have to be careful there.

[@itsd0nk]

I actually think the unlit bullet holes look better than the initial properly lit bullet holes in a few ways, from an artist’s perspective. And yes, I realize that through the process of iteration you would easily achieve yet superior visuals with the properly lit method. Just had to mention that the unlit style kind of looks more like a nice diffused lighting is happening in the holes than the aggressively shadowy well lit holes looked.

[@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!

[@whtiequillBj]

32:13, it is also possible they are using image based holes because they are in the pre-visualization phase and it was faster to program. Its also possible Valve has some black magic to take image values and convert them into voxel values and it isn't actually being faked.

[@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

[@lolotronop]

That Kaiki on "faking" was really good. And God... Why did you have to use HIM. Glad you got a sponsor btw. Just watched a couple minutes and the video is already amazing

[@rusty_tendrils]

Some observations about the showcase video: 1. Bullets were always shot near the surface of the smoke (than the core). 2. Weird artifacts when grenade exploded on smoke. 3. No tube-ish shape when a bullet is shot through the smoke. So, they probably used a stencil buffer and the random bullet shot texture is the stencil? They didn't shoot near the core as it would give it away as a tube-ish shape would be expected.

[@CrypticSpoon1]

You cannot believe how excited i was when i realised you did the same thing as the montogatri series in the intros of your videos

[@samuels1123]

I believe the smoke volume is actually a legitimate 'simulation' where a voxel is given a 'pressure' value, compares that value to those around it, and moves between the average of the path of lowest resistance and a 'momentum' until voxels have too little pressure to continue or exceed a third 'lifetime'. The volume grid is most likely locally created 3d arrays which are aligned to appear like one map scale array, and are merged when overlapping, which can happen because of that third value. I believe the bullets work because there is some weird cursed mid-level heightmap with a clientside material The heightmap may interfere with the effect of the voxel presence up to a depth that resets and rapidly increases, becoming inf before the next shot, imagine it denting in the voxels according to that heightmap with it always aligned to the camera and then have smoke generate around that offset grid this produces the target effect with high precision and low cost as all it needs is one clientside material which messes with the input volume before rendering, but is vulnerable to tampering probably not how it works, but my guess into something similar

[@happyone234]

I WAS NOT EXPECTING A HAROLD AND MAUDE REFERENCE. NEW FAVORITE GENERAL CODING CHANNEL. SO MUCH SWAG. EPIC STYLE.