How One Developer Continues To Defy The Impossible 

I feel like not covering quake was a missed opportunity, as I feel it cleanly covers the transitionary step from doom to doom 3. with it haveing bsp trees implemented in full 3d with a software renderer, and a later option to use opengl.

That 3.6 kTri lightning bolt mesh really got me. It differs a lot from the poly budget my boss is trying to make me obey 😂

PCs in the 486 days (When DOOM released) most definitely had 'dedicated' video cards (CGA, EGA, VGA) with different color depths (amount of availble colors) and 2D acceleration... PCs required a video card for ALL output to a monitor... Without one, you could not use the computer... But, they had no 3D capabilities. That all changed when the 3DFX Voodoo add-on cards became popluar. And the start of the GPU race began.

the funny thing is that Quake source ports (fully 3D) require LESS computational power to run these days than modern Doom clone-engines (half 2D pseudo 3D) There was one guy that figured out how to achieve Multi-Threading in Doom software render reducing dramatically the CPU requirements for bigger intensive maps, but he probably realized what a massive cesspool of negativity Zdoom/GZdoom teams are to deal with and he never released it (why should he) So yeah thanks again gzdoom team, thanks a lot

I'm blown away by the amount of information you managed to squeeze in! Awesome work!

This was awesome, especially considering you're able to provide such technical information in such a digestible format. You got a new sub for sure.

The innovation id Software has continually showcased is why I've been a life long fan since 92.

You are definitely my favourite development deep-dive / Mark Williams lookalike on RU-vid.

If you're discussing id Tech, why did you skip Quake 1 and their iteration up to Doom 3? There were huge leaps forward in technology that led to Doom 3.

The original Call of Duty games also have that BSP system sort of, and you had to manually lay out the level portals for culling, which meant you had to design everything around it. I remember when I was younger it was a nightmare understanding that stuff properly. Back then there were no high quality YT videos or well written tutorials. Even for basic stuff like setting up materials for textures you had to write scripts and so on. Today all that stuff is automated or done visually via specialized tools (press a button and it does [thing] for you). So many engine limitations as well, like not being able to have more than four dynamic lights on any surface (as it was using RGB and Alpha channels), annoying memory limitations because 32bit and so on. Today it's just "here's your ray tracing, enjoy thousands of dynamic lights at once!".

Would just like to recommend the channel @Decino to anyone coming down to the comments with some more interest in the mechanics of Doom. This game has never stopped being interesting to me, the work of id software has been part of my academic career even. Really happy to see it covered like this light by Nathan Baggs here, there's just so much to talk about in terms of programming.

Great video! I think the jump should’ve been from doom2 to the quake engine which is where the real 3d magic occurred (and you could look up for the first time), even when not being doom games they were the real successors technology-wise. Then from quake 3 to doom3. Also the fact that John Carmack released the previous engine they developed as open source was something never before seen in the industry. Thanks for the great info!

Very interesting and structured approach to explaining this, good job!

Doom is one of the iconic science fiction video games of all time!

You came right out of the gate with a mistake :) Computers DID have graphics cards back in the days of Doom. They had to as the CPUs didn't have onboard graphics. But all the graphics cards for comsumers were 2D only. Quake 2 was the first of Id's games to support 3D graphics accelerators, released before Doom 3. I had a dedicated 3D card in my PC at the time that worked in a pass-through mode from the 2D card.

A wonderful introduction to the functioning of modern engines. Thank you so much.

Amazing video! Thank you for sharing your knowledge 🙌

Doubt you'll read this comment, but your worms 2 adventure have given me the inspiration & motivation to look at Rugby 08 again. I never knew about the programs you used in that video and was so thankful of you sharing that I had to make this comment.

What a beautiful research you have done here. Thank you.

The jump from Doom 1 to Doom 3 was a bit jarring, surely Quake and Rage are the missing pieces of the story here? Otherwise, insightful analysis!

Very solid explanation and I like your "normal" pacing. No informational bombardment or edgy cuts. You English people are like natural born educators, thank you!

i really love this way of explaining. i had to go for 0.75 speed because i am not super familiar with graphics engine internals and still have to think a bit in parallel to listening. but actually i understood everything you explained!

They're called fragment shaders in Vulkan (and OpenGL). "Pixel shaders" is a distinctly DirectX terminology.

Awesome video showcase, would love to see more in-depth information into Vulkan as I truly believe this is the future Graphics API considering it is a lot smoother/stable and crossplatform!

0:09 That derpy face you make always makes me smile.

The doom 3 section reminded me of that VERY COOL error that one guy had that made all textures fail, but all other steps (like light and whatnot) work properly, so it was an no texture game. I've wanted to play that errored Doom (2016) but no dice.

Fantastic breakdown of how the engines worked. Any chance of being able to do something similar with Ultima Underworld?

1:12 35 times a second* 2:10 You're talking about the reject table. BSP trees deal in 2D walls (in Doom's case) - IE - Walls/Line segments (linedefs in Doom parlance).

Very interesting stuff. Thanks for doing the video. There's something funky going on with the recordings of your voice. It sounds glitchy and sped up at times.

I bought a 484 66MHz pc with 8 MB (I think) and a 20 MB HDD back in 1995, and got Doom1 a little later and played that and Doom 2 for around 2 years straight. Good times.

I clearly remember the day I saw DOOM running and was amazed by the graphics

It is interesting how rendering engines need to completely change over time with changes to the hardware. The depth pre-pass in 7:07 was present in a lot of rendering engines for a long time. But now it actually hurts performance on mobile graphics hardware because they use a tile-based architecture(it doesn't render the scene in one go but in multiple square segments). It's very slow to read the result of a previous render pass so it is prefable to do "some" unecessary compution. If you have an engine that runs on both desktop and mobile you would need to enable/disable this pass depending on the hardware your game is running on.

This is so nerdy I love it as an amateur game developer. Please do the Halo series next, if possible.

Awesome video. Surprised you didn't delve into the Quake series since it bridges the gap between DOOM and DOOM 3.

Brilliant work, subscribed

All hail benevolent hyper-intelligent architect of the post-singularity simulation we all live in, John Carmack.

I like how Nathan's voice goes into Darth Vader mode every now and then

Respect for id software creating innovations in gaming technology!

Hey Nathan, this is the second vid I watched of yours and I'm not even half way through, subscribed, you offer a very detailed and easy to follow explanation of things, you need to start a patreon, I have paid good money to go to a course to learn some similar stuff in 2006 with multimedia and Maya etc. Here you are giving it away for free and your stuff is highly advanced. it is deep back end stuff. really helpful and useful. I have an interest in this stuff but lately not very motivated. on your own there is no match for competing with teams who are established. I am sure you could offer some established developers a lot of great advice. I would certainly hire you to refine some processes if I had an established company in the field.

Thank you for your research and the making of this video

Instant sub, this analysis was brilliant

Amazing Video with great detail

The depth masks look like those you can produce in consumer level graphics programs such as Bryce or Vue, which give you great control over post processing of the color render in your photo editor.

love my lightning bolts being >3k triangles, makes all the difference.

The “look up” thing was very entertaining 😊

Amazing video, i enjoyed throughly, thank you.

John Carmack My Hero.

Amazing video, thank you! 👍

wow...awesome research & video. thanks.

18:04 the one thing that has remained consistent in all the different Doom engines, is the pursuit of efficiency and optimization

Please don’t use Adobe Enhance in your future videos. It gives voices a bizarre uncanny quality that is rather uncomfortable to listen to. I can assure you that normal noise removal within your video editor of choice would be more than sufficient, if that’s your concern.

Fantastic job

The massive textures was a Id Tech special that got introduced in Rage with id tech 5!

great video!

If I remember correctly, 4 MB RAM an 12 Mhz is about sufficient to start the game, that's it. It would run less then smoothly to say the least. When I started playing it I had a 486/66 with 8MB, and it ran as shown in the video.

What must it be like to be so brilliant and create something so creative and so iconic? It must be wonderful.

Great video! What monitor/s are you using?

PC have always had graphics cards, integrated graphics is more of a modern thing than a retro thing. It was graphics cards with 3d Acceleration wasn't a thing when doom came out. It was probably doom and other games like it that created a need and demand for such a product.

this is very clear even though it's full of information, very good video...

Mb is Megabit, MB is Megabyte. Annoyed me more than it should. Great vid though.

True nostalgia! :)

00:35 In 1993 computers had dedicated graphics cards. That was the only kind of graphics card back then. What computers didn't have was a 3D accelerator or GPU.

Such an impressive dive-in considering the amount of information together with the ease of explanations, great video!

It’s crazy how inefficient that multi pass forward shading is in doom 3 unless they actually optimize it to combine multiple lights into one draw call. You could draw an object once and send some hardcoded max amount of lights per draw call instead, which is usually 4. So if an object is hit by multiple lights, you do own draw call instead of multiple draw calls for each light. Heh another random tidbit. The zbuffer isn’t compressed down to only red. A single channel image is typically displayed as red because it’s interpreted as RGB but you’re missing the GB portion so you only have red information. Shades of gray are technically the presence of all channels, RGB with the same value. It might have compressed a 32 but or 16 but zbuffer down to 8 bits so it could fit into one channel of a gbuffer, but depth is actually one of the things you want to avoid compressing and keep at as high a precision as possible, or you get issues like z fighting and other ugly artifacts. You might also use the zbuffer to figure out world positions per pixel when doing deferred shading or other things and if it’s too inaccurate, the positions aren’t derived as accurately.

lol,of course there was dedicated graphics card. What wasn’t a thing yet was consumer 3D accelerators, which nowadays are integrated into graphics cards

I remember when Doom first came out. Many a game session with friends ended up with playing either Doom or Dune 2. And the same conclusion applied to me: I was terrible at all FPS games.

I love when you showed each separate draw call for a single frame in render doc, it’s so sick

In a sense, the blueprint for DOOM could be the blueprint for GenAI game rendering.

Overall, this was pretty interesting. The Doom engines have been pretty ground breaking on a technology level.

apitrace can trim to a set of frames (though there's now a new command called gltrim that makes it easier)

Quality videos 👍👍 Would like to see more reverse engineering and game hacking.

AO let’s go, now the song makes sense!

Amazing to think that these calculations are even possible in such a short space of time, now emagine that some of calculations are doubled when in a VR as well as having all of the spacial awareness calculations for 6dof as well and in 120hz meaning each render takes half the time to process and render than in 60fps. It's truly mind-blowing and this isn't even a heavy game

Doom walked so Quake could run, it used tons of crazy optimizations and rendering tricks

What one can point out is, that Doom: Eternal doesn’t do that much work 60 times per second. It does it waaay past 100, sometimes even 200 times per second! This engine is crazy efficient and manages to push insane framerates, for the graphic fidelity. The fact, that it does all this work and still manages to pump out high FPS on older GPUs, is really impressive.

enjoyed !

0:58 you say about "24 mega bytes [MB]" yet on the screen is "24 mega bits [Mb]" so 8 times less. Also, MHz, not Mhz :)

The dayz of softram and mitigations, miss those dayz

Quake was before Doom 3. You could look up in both Quake 1 and 2 already.

4:28 they are all OpenGL backends just with different vendor extensions.

Base requirements are wrong - Doom required a 386 at 33 MHz. It could run on slower hardware (but it had to be 32-bit) with strongly degraded graphics.

Do you know if the changes, features and discoveries made during the writing of one of those engines are carried over the following iteration of the engine ? Let's pick Rage for instance, does its engine contains the code for Doom 3's per pixel lightmapping system or makes use of it ?

Umm... computers in the early 90's absolutely DID have dedicated graphics cards! They just didn't have 3D accelerators in them. That was the time of VGA and SVGA. Doom is a software renderer but it still needs a graphics card.

13:50 into the video, and I have maybe stupid question. Is the computer (cpu, gpu ...) doing this every frame of the game? When these calculations are being made? Less FPS fewer calculations, more frames per sec more calculations?

I remembering buying a Monster 3D graphics card so I could play GLQuake.

I wonder how the destructible demons tech works. If it is done with tessellation shaders like in Nvidia’s triangles vs aliens demo.

Sir... Computers (back then) had dedicated graphics cards. Most of us were using Trident, S3 or Cirrus chipsets with Vesa drivers.😮

Did you mix up dedicated graphics card and GPUs? Even my 286 had a deficated oak graphics card. We didnt have APUs back then. Maybe you mean something specific that im not understanding, can you clarify? Thanks for the video!

The main disappointment in Doom3 rendering techniques is the flash light. It's essentially a 2D sprite blended on a 3D-scence in screen space. That is common for 2D-ligthing but embarrasing for a 3D game that has a focus on lighting.

Blud want us to think he is the genius almighty mastermind and master of invention ahead of his time and the alien in human frame john carmack

Great video, definitely feels like talking Doom engine technology while skipping the entire Quake franchise that happened in the middle, skips a lot of development that is tied to ID Tech engines that happened between 1990s doom and Doom 3 (Quake 1 to 3 were released during that time frame and are massive upgrades to original doom visually, too much time passed between original doom games and doom 3). Perhaps it would make the video too long for the purpose of it but there's so many massive changes that occurred during that time.

Why no quake exploration? 😭😭

renderdoc is the greatest graphics api debugging tool

would be cool to see how dlss integrates to the render pipeline

Could you demonstrate debugging windows program on linux with wine? Following wine logs only get you so far and require true debuggers but can be hard at times with anticheat/ detached processes so i would love if u could give it a shot.

Very interesting video. Too bad Wolfenstein and Quake were not featured, especially the Wolfenstein Raycaster was revolutionary because it did 3D largely without floats and divisions.. And Quake had super advanced software rendering especially because of its dynamic lighting..

Damn, i need to try writing an engine. not because it'll be good. But because it'll be educational.

doom 3 was revolutionary. graphics were mind blowing

Carmack is a genius yeah.

You should have at least briefly talked about QUAKE I, II, & III before Doom III being it's the same developer, same genre, preceded DOOM III, required graphics cards, ability to look 360 degrees in games, etc. I really only have an issue because of the title. You should have named the video "DOOM - How One Developer Defied The Impossible".