Adding ray tracing (back) to my game engine [Voxel Devlog #17]

Online demo: github.com/DouglasDwyer/octo-...
Additional voxel models: drive.google.com/drive/folder...
It's time for another devlog, and the engine has undergone a ground-up rewrite! In this video, I showcase the new ray marched graphics. I discuss the drawbacks of rasterization and the importance of two attributes in voxel engines: per-voxel colors and per-voxel normals. Then, I explain the performance improvements in this iteration of the engine over my initial attempts two years ago.
Music used in the video:
Karl Casey @ White Bat Audio - The Saga
Chris Doerksen - Chase
Karl Casey @ White Bat Audio - End Credits

[@DouglasDwyer]

Want to learn how to write powerful, high-performance code? Then be sure to check out CodeCrafters using the link below, and help support my channel: app.codecrafters.io/join?via=DouglasDwyer They have one project which is completely free to complete during their beta, and you can begin any of their projects for free! Get 40% off if you upgrade to a paid account within three days.

[@eszdman]

Great video, please try using frame interpolation based on ground-truth motion maps generated by GPU and then apply this map to previous frame multiple times

[@timmygilbert4102]

Bro I made that tetrahexaconta tree joke before 😢 no credit 😂 joke aside, you are wrong about rasterisation vs marching, use a GBuffer to resolve the lighting, independent of the rendering type. Also light probe might help as a light cache, which would open gather as scatter global illumination. Look at hddgi too, you basically have the structure to do it by default. You can also have nlogn ray update with hierarchical segment tracing cache in hierarchical lightprobe.

[@jktech2117]

bro why dont u make voxels that represent vertices instead of cubes? u will have less faces for a smoother look. but u might need to instead of doing culling u need to decide the shape of the voxel based on its neighbours, so depending on the situation if it cant be a vertex it will be like a lowpoly sphere if theres no neighbours, or something like this ynow? edit: this is exactly my plan for my game called pretend, but rn im working on more basic projects on irrlicht to get used to it and then progress using only irrlicht (since its faster and more compatible than godot)

[@ArthurWolf]

I had a dream. That every one of the "I made a voxel engine" youtubers came together to code an open-source voxel engine and put it on github under an open-source license, and it was so awesome and slick and efficient that the open-source community came together and rebuilt minecraft and hundreds of other games/mods on top of it. Then I woke up and I had to go to work :( Great video.

[@DouglasDwyer]

Sometimes I do wish that I could team up with another voxel KZbinr or two. We would be able to accomplish more, faster, than by working on our own.

[@NerferCo]

The Smoothieboard guy?? This is not a crossover I was expecting lol :)

[@ArthurWolf]

@@NerferCoAHAHA First time in 10 years I'm "recognized in public" :) I'm famous \o/ Did you use the board? We're working hard on v2, we'll be done shipping the kickstarter boards soon, I promise !

[@ArthurWolf]

@@DouglasDwyerMaybe ask? In my experience, that works much more often than people expect.

[@timmygilbert4102]

Given how they influence each other, by taking inspiration, that's working together in my book... Also I literally invented as a joke the word tetracontahexaconta for 1bit voxel, and guess who took large inspiration from it because I commented it? 😂 I know the literature on the subject, nobody else use that word, well now it's enshrined in his engine 😂

[@boyinjuly1]

This small niche of voxel engine ytubers is so comfy

[@DouglasDwyer]

We've become a remarkable little community, haven't we? :)

[@80sVectorz]

Not only have you gotten better on the technical side of things, but you have also improved a lot in video quality! Keep going man, love your stuff!

[@prltqdf9]

I wanted to make a comment like this but you already stole the show.

[@st20332]

ok​@@prltqdf9

[@plokki456]

The data structure you're describing is called an N^3-tree which generalize octrees. Since you use a branching factor of 4, that would be a 4^3 tree. As you noted, it's possible to efficiently traverse this structure thanks to the bitmask trick. A very efficient algorithm for traversal is called hierarchical DDA (digital differential analyser), which is more commonly used for dense voxel grids but can also be applied in a hierarchical fashion on each level. Note that you may use a different branching factor on each level in order to reduce the depth of the structure while still retaining good sparsity. There is a paper describing all of this called "VDB: High-Resolution Sparse Volumes with Dynamic Topology" in case you need a reference. In my own work, I use a 3 level hierarchy where the first level is dense and the following two use a branching factor of 4. Hope this helps :)

[@solenskinerable]

8^3 using avx has to be faster tho right?

[@plokki456]

@@solenskinerable avx is a set of vectorized floating-point arthmetic instructions on the cpu, right? This video and my comment were considering a gpu implementation. Now, in the case of cpu ray tracing, I suppose you could use vectorized instructions to trace multiple rays in parallel but this doesn't have anything to do with the datastructure. Ray tracing along a single ray remains a sequential operation that cannot be parallelized.

[@frozein]

Welcome back to raytracing! I’m really excited to see where you take this engine.

[@DouglasDwyer]

Thanks frozein! It seems like all of our engines are headed in that direction, huh?

[@frozein]

@@DouglasDwyer Yeah there's been some amazing progress from everyone lately!

[@TobiG4mer]

DUDE! 10:49 This reminds me of the old "Ace of Spades" game. Basically a voxel fps that could run on anything when I was a kid. I would love a sandbox game or anything really in a retro style like this! Keep going I got really excited while watching this video :D

[@stevy2]

That game was so good.

[@bigblackchode9628]

fun fact! to this day it is still playable and quite enjoyable. The 2 most used client implementations are OpenSpades and BetterSpades, the server list can be found on the build&shoot website

[@thephoenixsystem6765]

I was so sad when it died

[@GabeRundlett]

THC Tree 😅. I've heard it referred to before as a 64-tree

[@punchster289]

what about kd quaternary tree?

[@cvabds]

​@@punchster289what about CBD tree?

[@punchster289]

@@cvabds yes i like that one

[@goobus_floobus]

THC Tree is definitely sticking for me 🤣

[@bobby_tablez]

The low-res style is sick! I think it would suit a horror game very well.

[@Stormmblade]

It's got an interesting charm to it, like an old retro game except 3D and using voxels

[@dmaz123]

GPU memory isn't slow, it's way way faster than standard system memory. GPUs aren't designed though to be programmed like CPUs you need to take into account the architectural differences and leverage the GPUs huge advantages when designing memory structures to be run on them.

[@RJiiFin]

This so much.

[@TheDroidsb]

Holy crap that church looked amazing

[@goobus_floobus]

baked voxel lighting looks awesome - you can see it in Ethan Gore's demo too

[@TheDroidsb]

@@goobus_floobus yea I follow him as well 😂

[@goobus_floobus]

@@TheDroidsb Every time I see the scale of the world in his demo my brain explodes 😂

[@eugenevarbanets3898]

Lower resolution looks perfectly fine. imo it will create better result if used well

[@xima1]

Amazing progress, I love your devlogs! :)

[@DouglasDwyer]

Thanks for watching, Xima! Your engine is very inspiring. I'm excited to see where we can take web-based voxel graphics now that WebGPU is maturing.

[@GabeRundlett]

Lets go!

[@vitulus_]

Awesome! It's incredible that you had the motivation to re-write all of that.

[@StiffAftermath]

Nice to see the project coming along! Very excited! Thank you!

[@tommj4365]

great progress, I've been a fan of voxel worlds since I was a wee little child, so it's always a treat seeing some new progress in this arena

[@dannyhallo195]

Well DonE! I absolutely love the new vid style! Please keep up your good work!

[@harriehausenman8623]

Really beautiful! And the performance is insane 😲

[@EqualToBen]

Loved the video! also thanks for linking Gabe's channel that one's new to me

[@TheBestNameEverMade]

Also known as a multi-layer grid, I have used these a lot. You can actually make it a little more efficient memory wise for spatially by hashing multiple values in the same nodes. The first low resolution grid is sometimes also called a bloom filter. You can use a processor's vector instructions like SIMD, openvc or cuda to skip many empty bits at once.

[@ZYZZinVR]

just started my data structure/algorithms course and seeing why the efficiency can be so important even on personal projects is motivating

[@MyKaosLife]

Love this! I saw some other comments on further ways to optimize traversal & memory usage, but from now on the common term for the 4^3-tree models should obviously be the THC-tree model 😄

[@vast634]

I tried the demo, I was quicker than expected. Good work.

[@LegoDinoMan]

Easily my favourite KZbinr, another great upload!

[@Cilexius]

I think it is amazing what you were able to achieve with the surface normals. Not using polygons frees you of building the chunks with this geometry to render the voxels. Nice idea, really amazing !

[@TheDroidsb]

Super awesome! It is pretty funny how many dev log videos start with. “I decided to reprogram it from scratch” 😂 I am also guilty of doing this tho so can’t say much

[@strefalinux]

10k KZbinrs - "I'll optimize this engine, even with the cost of rewriting 11 thousand lines of code." Multimillion companies hiring hundreds of programmers - "It reaches 48 FPS on RTX 4090, that should be enough!" Thank you for the video, it's very informative. Great job!

[@gabrielbeaudin3546]

That's a very nice acheivment. Congrat

[@metacob]

I mean, if you're a programmer in your early 20s and you like CG programming - then you need to make your own voxel engine. I don't make the rules.

[@2dozen22s]

The resolution and resource scaling is perfect on this lol. 100% gpu and cpu usage across 32 threads, and 1100fps default window size to 280 at 1440p. Looking forward to seeing how this project progresses, great job on it!

[@connorsheehan1944]

This is so awesome!! The game looks amazing keep going!

[@DouglasDwyer]

Thanks for watching :)

[@trashman1358]

First time I've come across your channel. I've always felt voxels are like a computer making graphics like (checks notes) a Post-Impressionist oil painter. The church and village at the end of the vid? Both facinate and excite my brain for reasons I simply can't fathom. Love, love, love voxels and if that's your engine? You've absolutely cracked it visual wise. Subscribed.

[@RiverReeves23]

Excellent work. I'm happy you went back to ray tracing. It does look much better. I love the idea of using photogrammetry to build out levels. I think this would make a really interesting almost PS1 looking game.

[@DouglasDwyer]

The one frustrating thing with the photogrammetric models is that they are hollow on the inside. It would be really nice to preprocess them so that they are solid (and also have proper normals).

[@delko000]

This is amazing, continue your good work

[@RiverReeves23]

I've always loved voxels, since Ken Silverman's Voxlap engine. I love the destructibility in particular, since polygons can't really do this. I think you have the rare opportunity to push the medium. So if we take the concept of destruction and voxel physics. What other cool things can we do that is only achievable with voxels? What are the limitations with polygons? I really feel like the future of game dev will be in a medium similar to voxels but something like gaussian splatting. Where the engine works with atoms. Maybe it's best to think of voxels as atoms. It's really an exciting area that has been so neglected by developers. You're very lucky to be working in an area that is yet to be fully explored creatively.

[@AndrewTSq]

that looks amazing!

[@cblair1353]

The low resolution has a really cool old-school feeling to it; you should play around with a CRT post-processing pass, could look awesome with the right resolution settings!

[@YoloRealm]

This has to be the most immersive voxel engine I’ve seen so far

[@cho4d]

real scan environment looks so sick. with a little bit of hand finishing it would be an amazing level generation tool

[@harriehausenman8623]

Absolutely 🤗

[@MrAngryWh1te]

Very intresting to watch, thank you

[@dexio85]

Rerwriting is at the heart of gamedev :)

[@lanefaulhaber1824]

Looks crazy cool!

[@SubzeroBlack68]

Oh also wanted to say that I found your channel (which has been great by the way). Because of a random video "You can Parry Nukes" for that V.A. Proxy game. I thought, Man it would be cool if that slash or explosion could slice a mountain in half as it traveled forward. Then I started thinking of Voxel destruction and how Voxel art would be pretty good for showcasing that kind of destruction. (Even that game looks like it be transformed into a Voxel art style. Then ended up down a rabbit hole of Voxel plugins for Unreal then custom Voxel engines and such which led me here.

[@USBEN.]

Beautiful work.

[@TR-707]

awesome demo!

[@DouglasDwyer]

Glad you liked it!

[@sixmillionaccountssilenced6721]

Imagine Magic Carpet remake with this tech!!!! Destructable castles, volcanos, tremors, everything. :DD

[@iplet]

Woooo! He's back at it again with the rewrite! This guy is gonna be the next Notch!

[@DouglasDwyer]

That's the goal!

[@henkdesjaak9650]

Absolutely love the photoscans!!! Also, i think the formal term for a tree with 8^3 sized nodes is a B+tree, B as in binary, + as in more than two children.

[@pandemik0]

Love your work. Voxel engines have a nostalgic place for me. Games like the original Outcast or Comanche (this dates me) had astonishing visuals for their time. That a voxel engine was possible on 1992 when barely any games were 3D at all is testment to their potential. There's a certain charm and art style to low res combined with a blocky world that is worth exploring. Bonus if that means it can run on a potato or a very old machine. Great potential there.

[@DouglasDwyer]

Glad you enjoyed the video, and I agree about the nostalgic aesthetic :)

[@ewertonls_]

this looks so good, i find the low resolution version charming

[@alaskandonut]

Very cool dude!

[@caleboleary182]

Wow, this is so cool!

[@ytHUNTR]

wow this looks amazing

[@looksintolasers]

One of the things I always wanted in AoS was vehicles. Imagine driving around a map in a Jeep, or driving a self-propelled artillery to a strategic high point? I could never figure out how a vechicle would navigate voxel terrain, but this idea of "normals for each voxel" could make it work.

[@silentvoidx9267]

I really like the low res look, especially if you add moody lighting and fog

[@lubomirkurcak]

This is incredible!

[@ChubbaBubba2]

The lower resolution + voxel style together looks very nice. Perfect for lower end GPUs as well like you said.

[@mmiisshhaa]

damn dude, this is the coolest stuff in CS in my opinion. Such a good combination of math and algorithms/data structures, to make something that looks so cool, and if it wasn't for job prospects, I'd totally go for it. I'm in second year uni, in cs and physics, and I'm so split in what area I want to go in. I worked on my own shitty, completely entry level 3D rendering/physics engine, and it was so much fun. But the game industry is going through so much layoffs right now, and if I want to work on other physics simulations like robotics or autopilots, it seems like I'd need a masters, which idk if I'd go for. I'm so torn on what I should work on this summer, if I should continue working on my game engine, or get into AI which is probably the more employable path, but doesn't seem as interesting as this. Also from what I hear game devs don't earn as much as other software engineers, but I wouldn't call this type of thing "game dev", more like engine designer, right? does it pay adequately to how much work you have to put in? maybe I care about the pay too much...

[@DouglasDwyer]

I think that your concerns about money are understandable. There definitely are game engine and GPU-related jobs out there, but they are competitive to obtain and the games industry doesn't pay quite as well. I'm not sure what advice to give you, other than that I personally would not go into AI. The area is overhyped right now, especially since the field has a low skill floor. Anyway, maybe consider software jobs in other areas related to low-level programming? In addition to games industry jobs, there are positions at companies like Qualcomm and AMD for developing new GPU drivers and tech.

[@Bruiserjoe]

Video quality is great!

[@VesSaphia]

11:10 Looks even more nostalgic really.

[@davidhuculak1099]

Wait a sec.. i recognize you. I used your fork of cpal for getting audio to work on the web in my game engine. Thanks and keep it up with the rust graphics content!!

[@DouglasDwyer]

Yep, that's me! One day I will add audio to my own engine with it too.

[@SuperLlama88888]

Wow, great job! Hope you can also implement reflection and refraction!

[@DouglasDwyer]

Yep! Reflection, refraction, and volumetrics are all stuff that I want to try!

[@e3.14c4]

11:08 super cute, love it

[@kennethsmith5383]

Duuuuuuuuuuuuuude this is awesome. All these voxel games 😊

[@marcorademan8433]

I believe the "higher levels" of searching through the voxels is some form of spatial hashing (you "hash" the ray positions to a coarser grid, which is then used to iterate through smaller grids).

[@yegorwienski1236]

I love how the game looks on the IC, maybe even better than on the GTX.

[@stormyy_ow]

considering how fast these engines are at lower window resolutions, exploring upscaling options similar to DLSS might be a valuable win for lower end hardware. i think the nature of voxel scenes could lend themselves extremely well to certain upscaling techniques (or look ugly idk). would be fun to expiriment

[@jorge69696]

The low resolution gives me 90s vibes in a good way.

[@capslpop]

That church looks oddly familiar 🤔

[@DouglasDwyer]

Hey capslpop! Nice to see you here - I've actually been watching your channel since your first uploads two years ago. The Church of St. Sophia really is a nice test model, isn't it? Your channel was the first place that I saw it :)

[@capslpop]

Thanks for watching! Can't wait to see what you do in your next video :)!

[@zblurth855]

just here to say I love the low res look, look like one of those "demake" but with its own style and not just PS1/2 look

[@torq21]

The photoscan stuff is the best reminds me of Vagrant Story on PS1, some of the best lo-fi graphics ever made!

[@francescobigblak]

Man keep It up! The best voxel engine will be the one that gets published

[@DouglasDwyer]

Haha definitely

[@PersonManManManMan]

This looks cool

[@user-vi7kp6re2l]

Incredible! 😮

[@phylliida]

This video was great

[@Oho_o]

This is nice!

[@Xaymar]

Damn, this is impressive.

[@DE81L]

Cool video!

[@DouglasDwyer]

I'm glad you enjoyed it!

[@web_dev_cz]

Amazing :) What do you think could be done to prevent the low res version from "flickering"? Also, how do you calculate the voxel normal? From what I've seen you color the whole voxel one color instead per voxel face, no?

[@guylemmer7707]

Your brick tree is similar to cone marching just in grid aligned space, and could also be thought of as a sort of acceleration structure.

[@xXTrack394Xx]

Great video! I am curious if you plan on tweaking the shadows and lighting to make it more realistic? I noticed that there is a lot of ambient light being used. Any plans to use a raytracing/phong lighting system in the future?

[@DouglasDwyer]

Yes, I want to experiment with different kinds of lighting in the future. At the very least, I would want to support ambient occlusion and point lights. But having some kind of global illumination or other system would be cool too.

[@Arctan95]

Fantastic! Is there a game / project in mind for the engine, or are you planning to release the engine itself? Either way, great work and I enjoyed hearing about the more granular GPU challenges and solutions you encountered - thanks for sharing!

[@DouglasDwyer]

My goal is turn to the engine into a multiplayer platform where users can create their own experiences with mods/plugins. The rough project roadmap for me involves three steps. First, I want to finish the core engine. Then, I intend to build a small proof-of-concept game with it, and release that. Finally, I'll release the suite of modding tools and related stuff so that people can build and extend the engine.

[@Arctan95]

@@DouglasDwyer Sounds ambitious! Though you're clearly a very proficient GPU programmer, good luck to you!

[@maxarq]

very cool video

[@NyanCoder]

Wow, that "low resolution" looks very interesting IMO. Idk why, but it reminds me ps1, and it's fascinating that it's all voxels. I think there would be a lot of cases of making use a such style. And it's true pixel-art (without shifting and rotating pixels)

[@autodidact7127]

I love this yo

[@jerkofalltrades]

It all looks really good. Will other things, like transparency or volumetrics, be easier with this new method?

[@DouglasDwyer]

Volumetrics will absolutely be easier, since volumetrics involves accumulating the amount of light along a ray! I anticipate that transparency will be equally annoying to implement as in rasterization, just in a different way lol

[@lorincotto863]

Amazing!

[@therealpeter2267]

I get around 8 fps on integrated graphics in the church which is 8 more than I expected, good work! (laptop defaults to IGPU with chrome)

[@Jeka476]

Ray tracing you say? Oh, i see, that rays bouncing around and making super realistic... wait... it's ray marching

[@lumivesper]

Try and add FSR 3 for lower resolutions on integrated video cards. You might end up gaining quality, even with high-end specs for this specific engine. You can also consider exchanging the language to Zig, as benchmarks show it can be up to almost 10x faster than C.

[@stormy_vox]

could you please go into more detail about per voxel normals? either here or in another video?

[@iLEZ]

Fantastic! Why oh why don't we see more retro-style games using voxels? I guess the engine programming is difficult and non-standard, but old games like Outcast and even older games like Ecstatica were fantastic, and the low-rez example in the end of this video reminds me a lot of Ecstatica for example. More! More!

[@Jonas-Seiler]

Honestly, the low resolution example at the end looks much more interesting in my opinion. The high resolution shots, especially of the mediterranean cityscape, look sort of uncanny and moreover kind of lifeless. Could be sublime for horror games though I suppose.

[@arphaxadarphaxad1592]

Wow! (11:00) a multiplayer map for Gears [ War

[@arphaxadarphaxad1592]

Or Tomb Raider Death Maych/Free for All

[@Maxjoker98]

I think global illumination could really make your engine look *even* better. I recently learned about an interesting technique for global illumination from a channel called xima. In his voxel engine he is using a cellular-automata based global illumination model that runs in a compute shader(to great effect).

[@DouglasDwyer]

I just learned about Xima's cellular automata GI, and it looks revolutionary! But I'm not sure how it would scale to scenes with more voxels. That said, GI is definitely something that I would like to learn about. I agree that it could take the graphics to the next level on high-end GPUs.

[@Maxjoker98]

​@@DouglasDwyer I don't think the performance impact is as big as you might imagine for this technique. The cellular automata only needs updates when the light conditions change, probably works well with octree-like structures, and lends itself well to caching. Plus, there is really no need to tie the light updates to the framerate, or at any fixed rate. You could just GI-update a small region at a lower rate for lower-end GPUs - due to the cached results for the non-updated chunks performance might should be ok? Really I'm just guessing here, maybe ask him for help? He seemed really nice in the comments where I already asked him some questions along those lines earlier :P

[@DouglasDwyer]

I definitely will reach out to him in the future. What I meant in terms of scale was more referring to memory consumption. Every time you double the size of your scene, it consumes 8x the memory, since the cellular automata requires storing per-voxel data, right? So I wonder how the memory is compressed. But maybe Xima has a solution :)

[@Magnymbus]

Now I really wanna see it with multiple ray bounces. Deeper shadows would go a long way in bringing out the details.

[@monikagamer3039]

Incredible

[@jumbledfox2098]

god you're so cool, i hope i'm this good at programming one day

[@DouglasDwyer]

Just keep working hard and build new things! You can become an even better programmer :)

[@jumbledfox2098]

@@DouglasDwyer thank you! your channel, and many other programming ones, are very inspiring to me haha

[@XT449]

great video.

[@DouglasDwyer]

Glad that you liked it!