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Show HN: I wrote a C++ ray tracer from scratch without AI
- itsthecourier 3mo agofor the love of the game, very refreshing good ol' coding
- martiano 3mo agoHey HN, 5 years ago I was 17 and learning to code C/C++ in a coding bootcamp (42). One of the projects was a simple C ray tracer. I really enjoyed working on the project and always loved computer graphics, so I decided to create my own path tracer from scratch, in C++, without using any third-party libraries. I ended up working on it consistently for over a year, then sporadically when CG excitement hit me again. Recently I polished it and completed some unfinished features and decided to make it public, finally. It's a C++20 Path Tracer with a CPU renderer. It is able to render good-looking images with reasonable performance and sample count. Btw this was initially coded without AI, but I've used it for the recent clean up and features. This project is a personal favorite of mine, and it can improve a lot, so I'd love to hear your feedback.
- ttoinou 3mo agoCongrats ! Results look stunning
- shinycode 3mo agoCongrats on doing 42 and to have worked and shared your project, very nice results !
- hresvelgr 3mo agoGreat work, the examples look fantastic. I will say, it's misleading to put "without AI" in the title for you to then comment on your submission that you have in fact used it. While it may only be in a trivial capacity, you've still used it.
- martiano 3mo agoI get your point. I consider it fair with the disclaimer because the "manual" version was very similar to current but missing some love
- almostjazz 3mo agoMaybe you could set your manual version as the main branch and then have a separate AI-cleaned branch on the side? I think the manual version part is what is exciting people and drawing them in. Even if it is worse or doesn't work!
- mcronce 3mo agoYou think that an LLM provides "love"?
- pixelesque 3mo agoJFYI: Your inverse ray direction calculation is not NaN-safe: if rays are completely axis-parallel in one dimension, so the direction value is 0.0 for that axis, you'll be doing the val / 0.0 which results in a NaN... Also, as you're using full double/f64-precision all the time, you're leaving a fair bit of performance on the table: transcendentals (sin(), cos(), etc) in particular - can be a lot slower than when using f32, and generally double precision can be special-cased to particular areas of the renderer that need it (curve, sphere intersection, and some situations where volume scattering produces very small distances).
- deliveryboyman 3mo agoWhat's the proper way to handle a zero in the direction vector when calculating the reciprocal direction? Should it evaluate to infinity?
- pixelesque 3mo agoInverse is still 0.0 technically, but yes, there is a trick you can use with Inf and SIMD to mask them out, so Inf is sometimes used. However, I'd just condition it for the moment. so: invDirX = dirX != 0.0 ? 1.0 / dirX : 0.0; etc, etc for each dimension. Obviously doing the != 0.0 comparison is not great, as it suffers from potential issues again (especially if you have denormals), but you can generally get away with it I've found in most cases.
- adrian17 3mo ago> Also, as you're using full double/f64-precision all the time, you're leaving a fair bit of performance on the table There's another issue that popped up on my quick naive profiling run: std::shared_ptr<Material> in the HitRecord/HittableLightSample is assigned/copied and destroyed a lot, and somehow these refcount operations show up as half of all samples on my profile (presumably because even if there's no hit and the pointer stays nullptr, the smart pointer still must check if there's anything to deallocate).
- pixelesque 3mo ago
- pjmlp 3mo agoCongratulations on achieving it.
- smartmic 3mo ago> Btw this was initially coded without AI, but I've used it for the recent clean up and features Then it makes sense to update the submission title. To me it reads as if the project was written completely without the help of AI (which might be a quality badge to some), but it is not 100% true then. Anyhow, cool project ;)
- martiano 3mo agoThanks! I get your point about AI, but I think it's fair to say it's almost 100% AI free. I worked on it for ~15 months, vs 1 week now with AI. Previous results were quite similar
- gspr 3mo ago> think it's fair to say it's almost 100% AI free. So write "almost without AI" in the title, then!
- mywittyname 3mo ago> 1 week now with AI 1 week is enough to build out a full-featured application with AI if you know what you're doing and are using proper tooling. You may want to use a better metric to quantify what AI tooling did in the project.
- applfanboysbgon 3mo agoI am interested in hand-crafted software, and it feels deceptive when you put "no AI" in the title only to reveal there was. If you try to minimise its impact after, one wonders, if the impact was so minimal, why it was necessary. If you worked on it for 15 months without generated code, vs. 1 week with, why not finish the job? What was the purpose of introducing generated code in the last week, and could you not have taken a little more time to do it by hand given you already invested so much time into it?
- socalgal2 3mo agoMy experience is 1 week of AI can = a year of by hand development.
- manoji 3mo agoHey ! Great work , I wanted to try something like this as well to begin my journey into games and computer graphics . I would love to know what resources you used to learn.
- martiano 3mo agoThe greatest resource I've found on the internet is the Ray Tracing in One Weekend series. (https://raytracing.github.io/ https://raytracing.github.io/) You can start there and go pretty far. Also you can mix random papers you'll find and eventually just testing and experimenting yourself.
- MyHonestOpinon 3mo agoAmazing. What happened with your professional career ? Did this exercise help you out professionally ? One of my worries about AI is that doing these deep dives are a lot harder to justify.
- martiano 3mo agoI just launched the project, so can't say it helped me professionally yet. Almost all of the time invested in this was pre-AI. I agree it's harder to justify those deep dives but still worth it if you do it alongside AI IMO.
- MyHonestOpinon 3mo agoEven if the project didn't become popular. Have you been able to use it as part of your portfolio to get a job, or move into academia ? Perhaps what you learned in the project was useful in some other way ?
- martiano 3mo agoI have used it when applying to some jobs but no success so far. I think this project was useful because it allowed me to go deeper than I ever had in code. I had very though issues that required me to ask in forums etc. I had a bug with ray-triangle intersection that took me 3 months to find the cause. So it was good training and it's a great project to have on my portfolio. I'm sure it can help me if I apply for something related to computer graphics and maybe gaming.
- yardie 3mo agoHow did you like 42? Would you recommend it? I worked some great devs who came out of 42. They all wanted to be game developers. The industry is notoriously unreliable. So they pivoted to writing business software where the client actually pays you for more features. LOL.
- cultofmetatron 3mo agofor anybody else interested in this undertaking, I recommend this book https://pragprog.com/titles/jbtracer/the-ray-tracer-challenge/ https://pragprog.com/titles/jbtracer/the-ray-tracer-challeng...
- Alifatisk 3mo ago> without AI Now this is how you catch attention
- eleventen 3mo agoA C++ ray tracer from scratch was the course project for my computer graphics class in 2016. I enjoyed the exercise immensely. Not nearly as robust as yours of course.
- Quarrel 3mo agoI basically was ready to come on and make a snarky comment like this. "I wrote one in the '90s!". and then I saw the examples, and the feature set. I particularly like the blender-to-Luz export. It seems great. Good luck to OP.
- Phelinofist 3mo ago"Without AI" is the new "Written in Rust", SCNR
- tmtvl 3mo ago'Have you considered rewriting it without AI' seems like something I could see myself saying.
- ssenssei 3mo ago_" Btw this was initially coded without AI, but I've used it for the recent clean up and features. "_ ???
- ezekg 3mo agoWow, I also wrote a game 8 years ago and have been using AI to rebuild upon it. I'm excited to tell people that I wrote it from scratch without AI! Love these new rules!
- rameerez 3mo agoLook at the commit history. Out of 557 total commits in the repo, 510 have been done before the past 2 weeks. All those (minus 5 in 2023-2024) have been done on or before July 2022, months before ChatGPT had even launched. Out of the 47 commits in the last 2 weeks, 26 were README updates / CI / docs. The remaining 21 commits are clearly cleanups, speedups, bugfixes, and tangential features like Blender import/export. Which leaves us with 505/557 commits (90%) if we're not generous --or 531/557 commits (95%) in the best case-- of non-AI commits to the repo. OP clearly wrote most of the project by hand and has just been cleaning things up for public release the last couple weeks. Exactly as he disclosed in his comment.
- ezekg 3mo agoI also wrote a huge chunk of my game by hand 8 years ago, but I wouldn't lead with 'it's built without AI' now because that would be disingenuous.
- hardex 3mo agoIt all boils down to what each of you individually understands as "made with AI", which could be anything between using autocompletions and braindead vibecode.
- Gud 3mo agoSo… it has been written with AI?
- sharpfuryz 3mo agoHave you considered rewriting it in Rust? Not for any technical reason (I say it reflexively now)
- martiano 3mo agoNot really, but it would be fun. I really like Rust as well
- evilturnip 3mo agoRay tracing is one of those problems that is conceptually so simple, yet continues to take so much mindshare because of all the challenges to implementation.
- ivanjermakov 3mo agoMe too, but in TS/WebGPU: https://github.com/ivanjermakov/moonlight https://github.com/ivanjermakov/moonlight Very fun! Packing data for GPU-side BVH was quite tricky.
- martiano 3mo agoWow, pretty good. Why web?
- ivanjermakov 3mo agoThanks! Wanted to tackle WebGPU for making browser games.
- socalgal2 3mo agowhy not web? 1000x easier than native and 1000x easier to share
- tuinorizn 3mo ago[dead]
- py93 3mo agoVery cool!
- rajhphuyal 3mo agoGreat work on such a technically challenging project.
- ddtaylor 3mo agoHN ongoing support and disdain for AI is perplexing.
- jasonjmcghee 3mo agoThis is (or at least used to be) a right of passage in the graphics world. I think many people go through the very popular https://raytracing.github.io/ https://raytracing.github.io/ There was a big influx of this when Sebastian Lague did his video series on building a ray tracer.
- pixelesque 3mo agoAnd if you've decided you want to take it a bit more seriously, move on to: https://www.pbrt.org/ https://www.pbrt.org/ which is effectively the bible, and has been for years (I wrote mine and moved into the VFX industry when the Second edition was still out! - I feel old now)
- brianolson 3mo agoyup. me too. once upon a time that was a 2 week assignment in graphics class in college
- throwpoaster 3mo agoNice, I once built a ray tracer without using an SQL database.
- deadbabe 3mo agoI think these kind of projects fail to impress these days, with or without AI. You need a second order effect, like “I did X using this thing I built Y”, where X is the actual impressive part and the Y is just an implementation detail. Maybe like that Roman Empire Names thing.
- ahoka 3mo agoWithout AI is the new "in Rust".
- chadgpt3 3mo agoFlagged for misleading title, since you admitted to using AI.