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- Hacker News
- Hey HN, I built Spin Lab: a browser-based interactive explainer for table-tennis spin.
It visualizes topspin/backspin, spin rate, ball trajectory, bounce behavior, and why the opponent’s return reacts the way it does.
I built it because spin is central to table tennis, but most explanations are either too hand-wavy or too static. I wanted something you can scrub, slow down, and experiment with.
- Are you using flight trajectories with simulated drag and lift from Magnus effect?by threatripper
- You might consider emailing hn@ycombinator.com and asking about the standing of your account.by lunchbucket
- Wow,that sounds gread for the sport
Thanks Fable, we miss you
by StahlGuo - What really sent me for a spin is how long I wasted on this demo.by N_Lens
- Same hereby jeidoban
- I know nothing about table tennis, but love it visually! Awesome job
- I know very little about table tennis, but this visualisation is excellentby swiftcoder
- It would be great if we could use it for training with live measured data.by threatripper
- Yeah no idea but I've seen devices that are able to measure spin in real time.
- i feel like it would be better if it didn't have text that's clearly ai generatedby kenaan
- Got it, I can edit that bit, thanks for the feedback.
- Why? It all makes sense.
That being said on my cell phone, I can’t make heads or tails of this. Nothing really works.
by dyauspitr - I opened it on mobile, the first window shows up and the text cannot be scrolled through.
Also absolutely horrible UI and seems like you just put up whatever Fable shat out without checking or any thought. I am only saying this because you shared it for public feedback
by altmanaltman - Fair feedback. I've got zero UI skills - I just did put up whatever Fable gave out. That's true.
I put tons of time explaining spin physics to Fable - that was some effort on my part and that's it.
the UI feedback, I'll pass it Fable when its back :D
And yep it doesn't look good on mobile devices - try it on a desktop screen if you can, much better there.
- 120 rev/s on backspin = professional loop :D
I feel like the topic just scratches the surface; there are many more things that are way more interesting to talk about here.
For example: air density actually matters. Professional players sometimes struggle to make shots in different parts of the world. The balls are not the same either. Comparing DHS with Nittaku, for example, they have different properties and a different bounce. In my part of the world, DHS is the preferred ball, compared to the US, where, at least where I’ve been, they prefer Nittaku balls.
Now about the content:
The Bounce: This could have shown all three balls at the same time, instead of showing them one after another. That would make the effect clearer.
The Answer: This feels a bit odd, and I think something in the calculation is wrong because the usual push always goes over the table on backspin.
Overall, I get that this is a very simple representation of what table tennis is, but it gives me “I did it in 5 minutes with AI” vibes.
by syl5x - For sure yeah just scratches the surface for now
About the bounce and the answer: great feedback, thank you! When fable is back I'll incorporate these.
But no did not take just 5 minutes :D I was working on this since early Opus days and the output was consistently absolutely horrible. Fable was the first model to produce something okay - then I prompted it for hours explaining exactly what I want to demonstrate and had to even tell it explicitly a lot about how spin works - from my experience