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Hi, I'm James Darpinian. I post about various programming topics here, especially related to VR/AR, machine learning, and/or satellites.

You may have used some of the things I've made or worked on such as See A Satellite Tonight, Google Earth VR, and WebGL 2 in Chrome and Safari.

What makes a humanoid?

January 20, 2026

[The Humanoid Alignment Chart]

Four incorrect beliefs you may hold about iMessage

February 21, 2024

Apple has been touting iMessage as "end-to-end encrypted" for many years. "The first widely available messaging app to provide end-to-end encryption by default". Users understandably trust Apple to get this right, and believe that their messages are secure even from Apple. However, that trust is misplaced. Most beliefs users hold about iMessage end-to-end encryption are false.

28 Humanoid Robot Demos

February 9, 2024

The world of humanoid robots is exploding, and new demos are coming out seemingly every day. I'm keeping a list updated with every current humanoid effort that has at least a public demo video. You'll see dozens of projects at all scales, from one guy in his garage, to growing startups, to multinational conglomerates. Even if you follow the field pretty closely, I guarantee there will be at least one or two in this list you haven't seen yet. And there's even one you can buy right now! Scroll on to see them all, starting with some of the lesser known ones:

I'm sorry, but omnidirectional treadmills can't work and here's why

January 27, 2024

Another omnidirectional treadmill has been making the rounds this week. This one from Disney looks very cool, with a creative mechanism for moving the feet around that has a lot of advantages.

Unfortunately, the real issues with omnidirectional treadmills can't be solved by changing what happens at the feet, because the problem is all in your head. Specifically in your inner ear; your vestibular system. And this problem is unavoidable because it is rooted in the way we walk and ultimately in the laws of physics. So what exactly is the problem? And why does the idea keep getting traction regardless?

How "See A Satellite Tonight" Works

July 13, 2022

See A Satellite Tonight is my most successful side project so far, with 5 million users since launch in 2019. It's been entirely a solo project, and I've used it as a proving ground for a bunch of tech that I wanted to learn. It took dozens of APIs and services to put together the experience I wanted: [The front page of See A Satellite Tonight]

In this post I'll describe how it all works. Frontend tech, satellite-related calculations, backend tech, plus a little about my motivations for building the site.

Integer math in JavaScript

July 11, 2022

You may know that all numbers in JavaScript are 64 bit double-precision floating point values. This is sometimes convenient and it works pretty well as a default for novice programmers, who are often confused by integer math, and rightfully so when 1 / 2 = 0. Unfortunately, it makes things slow. Doubles take a lot of memory and floating point math is slower than integer math on CPUs. It's also inconvenient if you want to port existing code to JavaScript, because existing code usually expects to use integer math.

Fortunately, there is a way to make JavaScript do integer math, and it works remarkably well!

Mounting Valve Index Base Stations (without holes in walls)

July 11, 2022

Shower curtain tension rods are way better than tripods. They are cheap, strong, available everywhere, and designed to look nice permanently installed in a home. They work perfectly installed vertically floor-to-ceiling and take up only one square inch of floor space. Get a cheap camera mount and you're good to go. They also work for non-permanent installation of other small items like baby monitors or security cameras.

Scraping my own Hacker News comments

July 10, 2022

I've left a lot of comments on Hacker News since 2009, when I moved over from Slashdot. HN Search is great for finding old comments, but it can't see comment scores, which are private to the author of the comment. I thought it would be interesting to find my highest-voted comments, so I had to scrape my comments from HN myself. Here's how I did it:

Redirecting a Blogger blog

July 9, 2022

I just moved some posts here from an old Blogger blog that I made many years ago. Now that all my posts are here I wanted to redirect the whole old blog to this new one. Blogger doesn't have a built-in way to do it, but it can be done! Here's how:

How to test for Safari on Windows

July 9, 2022

"Safari on Windows?", you say. "That's impossible! Safari doesn't run on Windows." And you're right! I mean it used to, but Apple stopped supporting Windows way back in 2012. Which is a bummer for web developers who want to test Safari compatibility.

But...