[HN Gopher] Ball Pit
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       Ball Pit
        
       Author : memalign
       Score  : 107 points
       Date   : 2026-03-25 19:08 UTC (3 hours ago)
        
 (HTM) web link (codepen.io)
 (TXT) w3m dump (codepen.io)
        
       | newobj wrote:
       | path tracer?
        
         | newobj wrote:
         | nevermind i see the ssgi/traa code. looks great!
        
       | simlevesque wrote:
       | Beware: this might totally freeze your computer like it did for
       | me.
        
         | ninju wrote:
         | definitely needs a lot of computing power
        
           | wildrhythms wrote:
           | Runs smoothly and without crashes on my Pixel phone
        
         | amelius wrote:
         | Works fine on my phone, Firefox+GrapheneOS.
        
         | ivanjermakov wrote:
         | WebGPU moment (have same issue on Firefox/Linux).
        
         | daemonologist wrote:
         | Had to break out Chromium for this one - Firefox+Linux does
         | _not_ like webgpu (my whole DE started flickering).
        
           | mentalgear wrote:
           | I was amazed that it run smoothly on Firefox mac without
           | WebGPU.
        
       | p1necone wrote:
       | This runs pretty smoothly on my middling laptop CPU while looking
       | like a typical raytracing demo. I assume there's _some_ smoke and
       | mirrors involved?
        
         | h4ch1 wrote:
         | No, it's using the newish SSGI and TRAA webgpu nodes. The three
         | team has been making great progress with SSGI and webgpu in
         | general and i'd recommend checking it out if you're interested.
         | 
         | There's also a denoise node in three (not used in this
         | example), but SSGI still looks kinda blurry.
         | 
         | Work though is still going on:
         | https://github.com/mrdoob/three.js/issues/31892
        
           | Sharlin wrote:
           | Jesus Christ, trying to figure out what TRAA is (presumably
           | an anti-aliasing algorithm) and how it works and it's
           | entirely impossible to google.
        
             | menno-dot-ai wrote:
             | Temporal reprojection anti aliasing :)
             | 
             | https://www.threejs-blocks.com/docs/traaHD
        
               | Sharlin wrote:
               | The only thing even remotely related to graphics I found
               | was references to "TrAA" in forum posts from 2006 (yeah)
               | where I believe they referred to NVIDIA "Transparency AA"
               | or something like that. "TRAA", "TRAA meaning", "TRAA
               | graphics", "TRAA 3D" all gave fully irrelevant results :D
        
               | jldugger wrote:
               | If you make the assumption that "AA" is some form of
               | antialiasing, it's not too bad: first scholar[1] hit
               | expands the acronym to Temporal Reprojection Anti-
               | Aliasing                   [1]: https://scholar.google.co
               | m/scholar?hl=en&as_sdt=0%2C5&q=traa+anti+aliasing&btnG=
        
             | h4ch1 wrote:
             | TRAA basically works by using a history buffer, for example
             | using the last couple of frames, all jittered a little bit
             | to compute the pixel. There's still ghosting and smearing
             | that can happen though because of this technique, so you
             | have methods to counteract like subpixel correction where u
             | increase temporal alpha when velocity is subpixel, but that
             | can introduce some artifacts as well.
             | 
             | There's also SMAA T2x which the pmndrs team is planning on
             | integrating into their postprocessing package[0]. This
             | cryengine3 slideshow gives a nice overview of antialiasing
             | methods if you're interested:
             | http://iryoku.com/aacourse/downloads/13-Anti-Aliasing-
             | Method...
             | 
             | [0] https://github.com/pmndrs/postprocessing
             | 
             | This paper also provides a decent overview of TRAA: https:/
             | /fileadmin.cs.lth.se/cs/Education/EDAN35/projects/17C...
        
       | jessepasley wrote:
       | Is this marketing for the Shape Store? It's cool but I still
       | don't know when my area is getting a Shape Store.
        
         | adzm wrote:
         | I tried to be helpful and explain what the shape store was, but
         | found myself with a lack of words. Instead here is the know
         | your meme page: https://knowyourmeme.com/memes/the-shape-store-
         | ai-video
         | 
         | tldr it is an ai video, subtle analog horror / backrooms style
        
       | Rendello wrote:
       | Beautiful, this must have been an excellent learning experience
       | to make.
       | 
       | I've done some very basic rendering code in C from a rendering
       | internals course, and at the same time I'm learning about
       | perspective from the drawing/art side. I wonder how much learning
       | one would help the other, in a practical way.
        
         | akie wrote:
         | The author is a world renowned expert in 3D graphics.
        
       | verytrivial wrote:
       | For some context, I think this is by mr.doob of three.js fame.
        
       | hermitcrab wrote:
       | I'm a C++ programmer and only passingly familiar with web/JS
       | stuff. What libraries/technologies is this using, apart from
       | Javascript and three.js?
        
         | kurishutofu wrote:
         | it's the three.js library using the webgpu browser api, you can
         | open view and edit the source directly on the codepen page:)
        
       | CodeWriter23 wrote:
       | I was able to get all the balls stuck on the 'ceiling'. Bug or
       | feature?
        
       | RankingMember wrote:
       | > The babies look unhappy
       | 
       | > Add more balls
       | 
       | Fun simulation. The novelty of stuff like this still hasn't worn
       | off for me in this era where we've got ray tracing in-browser.
        
       | TacticalCoder wrote:
       | I have fond memories of visiting a university in the early 90s on
       | a demo day and there was a (physical) sphere in a Cornell box:
       | 
       | https://en.wikipedia.org/wiki/Cornell_box
       | 
       | And next to it was a super beefy computer doing a 3D rendering of
       | a similar scene.
       | 
       | 35 years+ later I've got "many spheres in a Cornell box"
       | rendering in my browser, love it : )
        
       | rbosinger wrote:
       | I opened that on a Pixel 9a and was impressed on how well it
       | worked. There's something neat about this.
        
       | artursapek wrote:
       | that's amazing. it runs so smoothly on my M4 Pro
        
       | petermcneeley wrote:
       | Nice! I raise https://www.shadertoy.com/view/3tcGD2
        
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       (page generated 2026-03-25 23:00 UTC)