When Optimisations Work, But for the Wrong Reasons
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- เผยแพร่เมื่อ 28 ม.ค. 2024
- Level of detail and imposters are effective optimizations that work for reasons you may not fully understand. Let's explore why, from a hardware perspective, these work.
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In this video, we explore the underlying reasons why optimizations like level of detail work. This involves understanding at a deep level, what the GPU expects in terms of data, what the hardware is optimized for, and how the pipeline and physical hardware units are setup.
References:
developer.nvidia.com/content/...
gpuopen.com/wp-content/upload...
www.amd.com/system/files/docu...
shaderbits.com/blog/octahedra...
www.humus.name/index.php?page...
www.g-truc.net/post-0662.html
developer.nvidia.com/gpugems/...
developer.arm.com/documentati...
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WolfFire Games Article: blog.wolfire.com/2010/10/Imposters
Another good video that talks about this is "Rasterization, Overshading, and the GBuffer" under the "An In-Depth look at Real-Time Rendering" Series on the Unreal Learning Centre.
of course none of it matters now because we got Nanite :O
Ok so not to be an ass but you used footage from Wolffire games website and it would be cool if you could link them in your description. They are a fantastic developer and deserve more recognition
@@lazygenie5616 Oops, I clearly wanted to credit everybody since I added their links in the video itself, and tried to include them all in the description.
I've edited the pinned comment to include anything missing.
Should it be better if we had hexagonial displays instead of square pixels?
This is the stuff about gamedev that almost nobody talks about, and if they do, it's way too indepth. I love channels like this. You're doing a lot for making people understand how complex and smart Game Engines and Render Tech actually are.
Hey guys welcome to my game tutorial. We're going to make a complete game from scratch.
2 episodes. Last video was rendering a jpg to the screen. Last upload 3 years ago.
Every time.
indeed. I am on the discord for the O3DE (Open 3D Engine) and they talk about stuff like this, but more so on the software level of course.
You can really observe how they shift things around in order to squeeze the best out of the engine performance. I am really admiring such people for their in depth work.
I guess those are the people who are rarely seen as he heroes they are, fiddling with this kind of stuff.
Like police or teachers.
Those people are so important but yet, the topic is so difficult for users that I can't imagine digging into it. Not with my life time span at least. Give me immortal life and I am totally up to learn it.
How ever I feel you mate. I don't understand any of it, but I'm so so thankful that there are people fkn with this kind of things.
Have a good one
@@aeoliunyou should not need a tutorial to make a game from scratch I'm not the best or most knowledgeable coder but I am making my own game engine using c++ and I mainly use c# but I'm getting it done
@@aeoliunhonestly I kinda get them. Very few people will watch it in comparison to a much faster tutorial on an already built game engine. Imagine the dedication and free time required to make such a long thing... If doing it alone seems awfully long, imagine having to record AND edit that video (potentially)
What do you do with this knowledge?
thank you so much for saying "impostor" at least a dozen times while not making a single among us reference, im proud of you
I didn't even think of among us when watching the video, my brain must be healing.
@@agushernandezquiroga9064 agreed. I think i am healing too
I haven’t thought about among us for 1 years.
GET OUT OF MY HEAD GET OUT OF MY HEAD GET OUT OF MY HEAD 📮🔪
oh hi tux
This also really helps explain how 4k gaming is possible on these GPUs. In terms of GPU usage efficiency, smaller pixels is effectively the same as having larger triangles. So while 4k screens have 4x as many pixels, you're also throwing away far less work that the GPU is doing, which helps regain some of the performance loss
im wondering if eventually stuff like nanite gets integrated on a software level for gpu drivers and the architecture architects just go yolo and increase 2x2 quads to 3x3 nines or 4x4 sixteens. or a mosaic pattern of pixel groups that mimics and has statistically highest coverage with most common triangles, so that less culling is in place.
@@vanqy. You can't put that type of thing on the driver level, maybe the API level.
Conversely it also explains why using technology like DLSS to render at ever smaller and smaller resolutions doesn't improve the performance nearly as much as you'd expect. Like, you'd think rendering at 480p should be orders of magnitude faster than rendering at 4k, since there's orders of magnitude less pixels, but it's only a little faster.
I like that Epic's approach to finding out that subpixel polygons kill render times isn't to tell artists to avoid intricate geometric detail and to make more LoDs, it's to double down and make a system that lets the artist go absolutely wild with detail and not need to even think about LoDs.
This was incredibly challenging and I think it was the end result of a decade of research.
@@djmips Decade to find bottle neck. Some month to fix one.
There is one downside to it however, mostly from inexperienced devs working with Nanite, people are using Nanite as excuse to have extremely high detailed models in the game, even for things the player will never be close enough to notice. While Nanite alleviates many issues with the performance of such assets, it leads to far, far larger game sizes as many people just throw high detail photogrammetry scans into the game. Just because Nanite can handle automatic LOD doesn't mean no effort should go into optimizing the base mesh still, just that you don't need to author LODs manually, the base model still shouldn't be far more detailed than it needs to be, we already have 300GB games now, we don't need 500GB games because people throw in hundreds of 5-10GB models.
@@DreadKyllerNanite also prebakes and quantizes meshes, so there's really no excuse as it's basically moving a slider.
@@DreadKyller GTA V is over 10 years old, and 100GB in size, games should be 1TB in size by now...too bad Storage tech hasn't kept up.
One LOD technique I like a lot especially in the mobile world where nanite-like LOD engines currently aren't feasible is Progressively Ordered Primitives/POP buffers. The core idea is to cluster vertices through quantization at different levels of precision and sort them such that lower-precision vertices are first in the vertex list and higher-precision ones are last. The end-result is you can change the LOD of a model just by changing the quantization level and how many vertices you choose to draw without storing any more data than original mesh used.
The benefit is four-fold:
- Artists only need to make one model with any arbitrary attributes
- Cracks/seams can be handled perfectly
- Can have dynamically adjustable LOD levels without popping from mesh swaps
- Can stream in the extra vertices as they're needed or upload the whole vertex buffer once and instance multiple LOD levels in one draw call. The latter is useful as draw calls are still disproportionately expensive on mobile.
Since you're sorting the vertex list anyway (which can be done in O(n) time) and vertex order within quantization clusters doesn't matter much, you can also sort them on a secondary level to maximize vertex fetch efficiency which is important for mobile because of binning (more-so than overdraw since tile-based deferred renderers often have near-perfect hidden surface removal). The neat thing is you can scale the quantization level according to how large quantized grid would make triangles appear on screen to help maximize quad occupancy while maintaining enough detail for it to look good.
It does have some drawbacks, notably that it doesn't play well with vertex skinning and lower LOD levels tend to have a bit more triangles than hand-made LODs, but it's great in a mobile environment or for procedural mesh LODs.
As a side note, optimizing for mobile tile-based deferred-rendering is a lot of fun and it feels so much more rewarding to make a mobile engine run fast. Most mobile developers just port PC games or graphics techniques to mobile as-is and call it a day while limiting gameplay to negate poor performance; however, with careful optimization you can achieve between Xbox 360 and Xbox One levels of performance on most modern (>5 year old) mobile hardware. I'm definitely biased though as I've found my niche in mobile optimization.
That sounds amazingly cool! Can you say what you've worked on?
(Sorry for going of on a tangent here, I'm just musing 😅)
I've always found the capability of these mobile chips to be bizarrely good, so seeing stuff like full Resident Evil running on an iphone wasn't *that* shocking, but I've found it weird and a bit disappointing that despite this the market doesn't seem to care about it at all.
The Steam Deck and Switch's popularity implies there are absolutely potential buyers, but why aren't they biting? It's far cheaper to get a game controller attachment than these devices after all, so it shouldn't be input. Is it just *relative* to the Candy Crushes of the world that they don't show up? Poor app store presentation? Investors not willing to back it?
Awesome, I didn't know that. As someone who hopes to someday make a mobile game that isn't hot garbage this gives me hope.
@@SimonBuchanNzThis is due to a couple of factors.
1: The mobile market has been dominated by F2P monetization models since the mid-2010s. Paying even $5 for a fully-fledged game was a thing of the past a very long time ago, especially when you consider regions that the mobile market is at its most popular in: the whale-hunting model is especially effective.
2: The Switch is a 7-year-old console powered by a 12-year-old chipset. High-end smartphones exceeded the Switch’s hardware capabilities years ago, especially Apple hardware.
3: The iOS port of RE8 is exclusive to the highest-end versions of Apple’s highest-end smartphone, limiting potential audience significantly.
4: Resident Evil 8 is built upon a game engine *designed* for modern scalability on top of being a game originally built for last-generation home consoles as-is, as opposed to now where the hardware difference between the average smartphone and a current-generation console is somewhere in the ballpark of 3000%.
5. Newer console hardware and game engines has allowed developers to spend less and less time needing to optimize their assets, but it’s still faster and easier to build your game from-the-ground-up around the hardware you’re targeting anyway, especially if expensive graphical effects are integral to gameplay systems and your game’s art direction.
I like your funny words magic technology man
I don't see how that would work. You could order the vertex buffer, sure, but you'd still need entirely separate index data for each optimization level.
I am an absolute novice at game dev whos been toying around in Unity and now Godot for about two years, and I have to say each one of your videos feels like I should be paying you for this kind of info. The fact that this is your FREE content is insane, and I'm excited to see what your paid content looks like. You have a knack for beginning small, simple, and approachable, and then expanding to the point that I'm pausing and writing things down and yet still not feeling overwhelmed. I've read through documentation and white papers before for plenty of other coding subjects, but nothing has ever made me WANT to like your videos do.
I am aswell, probably even more novice.
I am so happy you're using Godot. Open source is a really good thing imo. Do you know the project from a finnish dev called: Road to Vostok?
He started his project in Unity, and then ported it to Godot. And I really think the port does look good, regardless of the let's say less lighthing etc.
Go guys! :D
If you want to get into paid resources worth their price(?) then I hear books on graphics programming are good.
@Techno tuna, but you are paying it, by watching it dude.
Nothing is stopping you from donating
He DOES have a Teachable if you want to buy full courses.
14:30 the "maximum area" triangulation improving performance so much is news to me! I usually create slices since it looks "nicer", but I should probably think more about the final result.
optimize when you know your targets and know you're going to need it. you can't "optimize" everything. it's wasteful.
if you can do "worst case" example scene and figure out how well it runs on the hardware you're targeting, then you might be able to get some inkling early of how to balance things out and spend your texture/triangle budgets.
For the art itself, most people suggest trying to get even, quad-only topology. They don't tend to worry about triangulation performance. Stuff like UV density and how textures stretch when animated tend to dominate.
For example, I wouldn't even bother trying to act on stuff like that "maximum area" example vs triangle fans, etc. That was more a tech demonstration to exacerbate a problem, rather than sound art advice. That all said, it can be good to avoid long, thin stuff when possible and to prefer workarounds, especially at lower LODs. For example maybe it's best at low LOD to have a flat quad with an alpha cutout texture instead of a lot of polygons that form boards on a bridge.
And when making LODs, it can be good to zoom an object out to its max distance it will appear at that LOD, look in wireframe, and see how big polygons are compared to pixels they cover. That can give you some good ideas of how to spread out detail, and where to reduce detail.
Or, if you're using UE5, enable nanite. Then you don't have to care :D
The maximum area is probably also the worst looking. Many rendering techniques look way better when the density of triangles is uniform along a model surface. And this is more important than small optimization.
@@blarghblarghActually, for the “maximum area” triangulation I found a method in Blender that makes these triangulations super easy to construct.
Step 0: Bind Checker Deselect to a key of your choice(here I’ll use Mouse5)
Step 1: Select the circle loop
Step 2: Alternate Mouse5 and F until you’ve run out of smaller triangulations/hit an edge
Step 3: Select all the overlapping faces and hit Delete, then “Only Faces”
Step 4: Select the edge loop, it’ll automatically select every edge in there
Congratulations, you now have an optimally-triangulated circle.
@@crimson-foxtwitch2581 nice one! thanks for the tip
@@thecat8411 I usually do the triangle fan out of habit, even on flat geometry or the bottoms of things. There are certainly cases where it'll look worse, but also cases where I did more work (usually extruding a default circular face and merging it to a point) for less than zero gain. Blender's default circle triangulation looks nearly the same as this "max area" algorithm.
Ill confess, even up until about 10 minites in I has assumed, naively, that I did actually understand why billboards were so kuch better for performance, with thoughts along the line of "reading a precalculated viewing angle from a file/ram is MUCH cheaper than doing the matrix multiplication to calculate the physics perspective appearance of even a very low poly 3D mode".
When you went through how the physically arcitexture of the GPU differently handles triangles with a size close to the pixel size, it was so mind-blowing. I haven't realised I was so starkly wrong about something in a while, such a great feeling!
That may have been the case a very long time ago. In 2016 my laptop still ran vertex shaders on the CPU. Intel GMA architecture - absolute garbage. Thankfully Intel stopped using that architecture and put real GPUs on their chips.
@@thewhitefalcon8539They stopped using that way before 2016
Really enjoyed this! As an artist you get told what things to avoid - e.g. long thin triangles and extremely small triangles, but it's rare to get a good explainer on *why*.
Now send this to Mortal Kombat
What do you mean? I don't get it
One iconic example of billboards is the infamous 1000 Heartless fight in Kingdom Hearts 2. Back then, it would've been impossible to have 1000 entities individually moving and acting all at the same time. Square Enix's work around to this was to have only have a handful of active enemies actually nearby. Meanwhile, the rest of the Heartless would be represented by these 'billboards'. While in combat, it's hard to notice this detail at first, but it's extremely obvious on repeat playthroughs. This work around is also present when there's a swarm of Rapid Thrusters, except it's a lot less noticeable since the enemies are flying above you and often spawn offscreen rather than right in front of the player.
“I’ve always been interested in optimizations” man I wish this was a requirement to work for any big game company 😭
I don’t think I’ve seen anything that talk about this stuff in this much detail, much respect for your career choice, I am truly amazed at the information dump and how accessible you’ve made it, thank you.
this channel is insanely underrated. The amount of knowledge you offer with each video is absolutely great. Pleas keep this up.
This is a very nice video! I have heard avoiding micro triangles is a big thing but now I finally know why
Nice profile pic
This is an amazing video.
Really good information in a short and clear video. And this is information that is not found too often on TH-cam.
Much appreciated!
Wow, this really explains why Nanite was such a breakthrough, of course it doesn't dig into the difficulty of implementation, but it does show how it eliminates the excessive tiny triangle issue.
Raytracing will replace rasterization sometime and then nanite will have become obsolete.
@@lanchanoinguyen2914 we don't have a clear picture when that transition will happen, so a solution that solves problems now is still valuable, and understanding the limitations of those solutions is also valuable.
it's like saying "eventually we'll have cheap consumer space travel, so who cares about light rail?". maybe not as extreme, since full scene tracing with no rasterization MIGHT be plausible within the next 10 years. but I kinda doubt it. not only does the hardware that supports such a thing have to come out, but everyone has to have bought it and phased out older hardware, too. unless you're saying current high end gaming hardware is already capable of doing zero rasterization and getting all the same level of effects. I am not sure I've heard anything that says that's true.
I doubt rasterization is going away any time soon, considering every GPU available today has a rasterization pipeline, and future GPUs have to keep a rasterization pipeline to maintain compatibility with
- any web browser
- any game on Steam (or GOG, or the Epic Games Store, etc.)
- any commercial software
Realtime raytracing is a neat addition to modern graphics cards, for sure, but it's not a silver bullet by any means.
1) We're extremely far from that happening
2) It's not like raytracing is immune to triangle counts
@@lanchanoinguyen2914how come? What does one thing do with the other?
Thank you a ton for the captions, really made it much easier to follow! Great video :)
been hoping for content like this for many years, great job
You have by far the best game optimization content I’ve come across, can really tell that you know what you’re talking about and not just repeating words said by someone else. Really love the way you explain things with just the right amount of information for you to be able to understand these things fundamentally and really grasp the mechanics 🙏🙏
You're amazing, glad to have found this channel. Thank you for this easy to understand and useful information!
Amazing video. Really like when I stumble on such high quality content.
Would really like a part 2 covering Nanite and maybe alternatives other people developed
Amazing video as always man! I have heard about this on the surface in my career, never found something that covers this subject with so much ease before, thanks
The moment I saw the 2x2 grid in the thumbnail and you mentioned LODs I knew exactly that this is gonna be about workflow scheduling for fragment shaders. Great video as always
This video is an absolute gem, Really thank you Simon for putting this up and making this so straightforward. Really got some deep insights about how GPU's work.
This is fascinating, and very helpful. Thank you!
This is a joy to watch! Glad I found this video 🙏🏼
From one 20+ year dev to another, your content is solid. And thanks for mentioning ATI!
You are an excellent teacher, the language and presentation was so easy to process even though I am only tangentially related to the topic, thanks for making this!
Amazing. Not only does this explain why intuition fails, but you also back up the technical reasoning with real industry solutions.
Watching your videos, I somehow always come out with more information than I was expecting. Well done!
Creators like you kept me motivated and today I'm a 3D and tech artist in my team. I'm not hardcore into graphics programming (yet) but I'm learning! One baby step at a time.
This is so incredibly in-depth, I learned so much from this video
This is fantastic, thank you Simon! Just bought both of your courses, looking forward to diving in.
Hope you get a lot out of them!
Dude, this video is awesome! You have such a straightforward way to express your knowledge that I, not a graphics programmer, get it. Kudos!
Crazy informative video! Big props
"Mommy, Daddy, where do pixels come from?"
SimonDev: "Sit down son"
Dude, amazing content. How interesting!
Thx for sharing your knowledge, cheers!
Back in the ‘90s, Marathon used “imposters” for all of the moving characters. They were all sprites. Animated sprites with versions from 8 separate angles.
Wonderful technical deep dive. Great job 👏
Thank you so so so much for this, this is extremely helpful!
Awesome video man. Really well presented
Thanks, this was actually really interesting and helpful!
Great stuff, thank you! I really should watch more of your videos ^^
Very well done. Even covered some stuff that never gets covered, like how billboards are used along with LOD and occlusion culling. They never talk about billboards. First time I made a model doing all this, I was floored at how well it worked. This stuff changed everything back in the day. You also said one of my favorite words, lol ... Automagically.
Absolutely love the way you explain things.
03:34 You just made my day for putting in Kai from the best TV Show ever made!
Simon! You are a saint! You even reference everything you mention. S tier content 👌
Man, thank you for your channel!
I just found this through a reddit comment and I didn't knew how much I needed to know this. Thank so much for explaining. This is so valuable and I definetely will buy ad start with your game math course. Awesome stuff
What a great video, I kinda always wanted to understand the performance optimization techniques better, but just didn't really had time to do the digging. Thank you for your effort!
That's a fantastic explanation, thank you!
Great video :) This will be my go-to when people ask about mesh-related optimization!
Loved the video ! thanks for the content :)
Brilliant explanation!
Thank you
wow this feels like a masterclass, subscribed
Very interesting video, I’ve always wondered why more/smaller verticies were taxing on preformace and I’m glad that you made a video explaining it in a easy to understand manner
Finally! I no longer have to explain this every other day. Another brilliant coverage, well executed.
I mean, you'll still have to link to it every other day :D
So interesting. Thanks for your work, I really appreciate it!
I will watch it several times with taking notes and watch other resources to create understanding
Thank you for this Video. This is such an eye opening thing! I would have never assumed that the rasterizer expects triangles that are atleast 4x4 pixels. I have always assumed, that is was a simple less stuff render
Thank you Bob from Bobs burgers for explaining graphics optimization
this is a really good video and also i really like your voice. thank you for making this 😊
Awesome content, very informative ❤
These are the kinds of videos that inspire me to one day dive into the graphics side of computers. I've always wanted to touch shaders and 3D modeling, but it has always felt beyond my understanding. This helps.
In intro to 3D modelling we were told very sternly, "keep the triangle count to a minimum, and remove as many unnecessary triangles as possible.
So this is nothing new to my ears... but it is fun to listen to anyways.
Thank you. Very well communicated. Much appreciated.
WELL PUT TOGETHER VIDEO 👍
Very informative. I'm not a game developer but I enjoy understanding some of the complexities. I didn't realize that small triangles were an issue. Not being familiar with how gpu's work at that level of detail I'd figured a triangle is a triangle.
Thanks for the video, very easy to understand and very interesting
I very much appreciate the time you take to do these breakdowns!
There's always more to learn in the world of graphics programming - and it's a blessing to call it my career ^__^
Amazing teacher definitely gonna buy your courses
You just explained what is, really, a constant, complex technical process, in a way pretty much anyone can follow and understand, and that's more than can be said for a lot of teachers/professors...
I knew, for instance, a good amount of what was covered here, just accumulated knowledge over the years of gaming and satisfying my curiosity, and guessed cranking up sheer volume of triangles would tank FPS pretty quickly... But now, I actually understand *why*...
Thanks for the insight 😍
this is awesome! thank you!
Amazing video. Very well explained. It's funny, that even though I already knew why rendering tiny triangles is a problem, I never made the connection that thats the reason why lod works so well
Great video, very technical but clear witch is really great ! If you like it, keep up the good work
which
Great video, thank you!
That's awesome content as always
my adblocker works completely fine, but for your videos I always pause my adblockers so that I watch the ads and support your wonderful content ✨✨
Hah thanks so much! Very appreciated :)
Well you are really helping me develop my own game engine. Thanks a lot.
Amazing informative video in my OpenGL and Vulkan journey. Thank you!
Great video!
The Crew Motorfest uses imposters (or, as I got to know them many years ago, sprites) for trees when you're using the map and zoom out. It's a nice throwback to when I started PC gaming.
Thanks for the pretty helpful video)
This flipped a switch in my head; this all makes WAY more sense now!
Thank you!
Good luck on your ventures, non-binary black horned dragon dev! Take it ez! 😎 👍
delete this @@crackedemerald4930
EPIC STUFF
Thanks for mentioning life of a triangle.
This has helped me understand better into a current implementation that I wish to achieve in a new game I am making in how to make sure it can sustain a stable load and keep processes down and achieve a higher fps.
the best thing you can ever do for performance is just render less, and that means there's less art work and less programming work too. The pixelated, triangulated game art style isn't considered as ugly these days. Squares didn't stop Minecraft.
because of you i found Lexx, been trying to find it for the past 15-20 years :D thank you, subscription deserved from all the info (and the extra one)!!!
May his divine shadow fall upon you.
@@simondev758 More people need to know about Lexx!
Very useful infos, many thanks!
That software rasterizer part is fascinating. I would watch a video on that.
freaking good video! thx!
god these videos are so good dude
This was really interesting!
I’m so sad to hear about your esophagus cancer 😢. You’re my favorite youtuber I hope you get better soon!
This is golden content.
How many pixels were born while watching this? 😲 Great explanations, even I didn't understand half the stuff! Nice work!
Just love the John Carmack quote on the article 😂
This is going to be an interesting one
This sounds like H. Jon Benjamin is teaching me computer graphics, and it's amazing.
Great explanation of 2x2 quads, friend! I'd never really understood how to optimize for them before and I'm already excited to apply some of these tips.
i was thinking the same thing lmfao
This is amazing insight