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Signed Distance Functions: Modeling In Math

April 12, 2023 by 13 Comments

What if instead of defining a mesh as a series of vertices and edges in a 3D space, you could describe it as a single function? The easiest function would return the signed distance to the closest point (negative meaning you were inside the object). That’s precisely what a signed distance function (SDF) is. A signed distance field (also SDF) is just a voxel grid where the SDF is sampled at each point on the grid. First, we’ll discuss SDFs in 2D and then jump to 3D.

SDFs in 2D

A signed distance function in 2D is more straightforward to reason about so we’ll cover it first. Additionally, it is helpful for font rendering in specific scenarios. [Vassilis] of [Render Diagrams] has a beautiful demo on two-dimensional SDFs that covers the basics. The naive technique for rendering is to create a grid and calculate the distance at each point in the grid. If the distance is greater than the size of the grid cell, the pixel is not colored in. Negative values mean the pixel is colored in as the center of the pixel is inside the shape. By increasing the size of the grid, you can get better approximations of the actual shape of the SDF. So, why use this over a more traditional vector approach? The advantage is that the shape is represented by a single formula calculated at many points. Most modern computers are extraordinarily good at calculating the same thing thousands of times with slightly different parameters, often using the GPU. GLyphy is an SDF-based text renderer that uses OpenGL ES2 as a shader, as discussed at Linux conf in 2014. Freetype even merged an SDF renderer written by [Anuj Verma] back in 2020. Continue reading “Signed Distance Functions: Modeling In Math” →

Analog Anoraks: The Op Amp Contest Starts Now!

April 11, 2023 by 28 Comments

We thought it was time to give the analog side of Hackaday their chance to shine, and what’s the quintessential analog IC? The op amp! Whether you’re doing tricky signal conditioning, analog computations like it’s 1960, or just making music sound good, op amps are at the heart of many designs. This contest, starting right now, is your chance to show off what you can do with a good op amp, or a few.

And for everyone else, here’s your chance to dip your toes into the warm analog waters. Whether you’ve always wanted to build a Chua’s chaos circuit or just to listen to music, there’s probably an op-amp project that will fit your personal bill. All you have to do to enter is set up a project on Hackaday.io, and use the pull-down menu to enter. We welcome shows of op-amp bravado, naturally, but we’re also stoked to see your simple projects that might help our digital friends leave their world of black and white, and enter into the shades of grey.

Thanks to Digi-Key, our sponsor for the challenge, there are three $150 shopping sprees on the line for the winners. And as always, there are some honorable mention categories to help whet your analog whistle, and to give us an excuse to feature a lot of great projects. You’ve got until June 6, to get your entry in, but these aren’t necessarily simple builds, so get going now.

Continue reading “Analog Anoraks: The Op Amp Contest Starts Now!” →

A Miniature MNT For Every Pocket

April 11, 2023 by 35 Comments

Last time Hackaday went hands on with a product from German company MNT, it was the Reform laptop; a full size computer with a full feature set and fully open source design. Now they’re back with the same value proposition and feature set crammed into a much more adorable (and colorful!) package with the MNT Pocket Reform. If you want the big Reform’s open source philosophy in a body fit for a coat pocket, this might be the computing device for you.

To refresh your memory, MNT is a company that specializes in open source hardware and the software to support it. They are probably best known for the Reform, their first laptop. Its marquis feature is a fully open design, from the mechanical components (designed with OSS tools) to the PCBAs (designed with KiCad) to the software (designed with, uh, software). When originally shipped that product packed a DIMM-style System On Module (SOM) with a default configuration containing a quad core NXP i.MX8M Quad and 4GB of RAM, as well as mini PCIe Card and M key m.2 2280 slots on the motherboard for storage and connectivity. That computer was designed to be easily serviceable and included a plethora of full sized ports along with easy to source cylindrical battery cells. The Pocket Reform takes the same intent and channels it into a much smaller package.

Continue reading “A Miniature MNT For Every Pocket” →

Supercon 2022: Aedan Cullen Is Creating An AR System To Beat The Big Boys

April 10, 2023 by 10 Comments

There’s something very tantalizing about an augmented reality (AR) overlay that can provide information in daily life without having to glance at a smartphone display, even if it’s just for that sci-fi vibe. Creating a system that is both practical and useful is however far from easy, which is where Aedan Cullen‘s attempt at creating what he terms a ‘practical augmented reality device’.

In terms of requirements, this device would need to have a visual resolution comparable to that of a smartphone (50 pixels/degree) and with a comparable field of view (20 degrees diagonal). User input would need to be as versatile as a touchscreen, but ‘faster’, along with a battery life of at least 8 hours, and all of this in a package weighing less than 50 grams.

Continue reading “Supercon 2022: Aedan Cullen Is Creating An AR System To Beat The Big Boys” →

The Real John Wick-Style Bullet Proof Suit

April 10, 2023 by 55 Comments

If you’ve seen the John Wick movies, you’ve probably had to suspend your disbelief about many things, but the bulletproof suits are perhaps the hardest thing to swallow. They look like stylish suits but are impervious to just about anything at any range. What’s more is when you are hit, they seem to absorb all impact with no effect on the wearer at all.

You can keep running, firing, or karate kicking while the suit takes all of the bullets. You can even pull your jacket up over your face if you want to protect that million-dollar smile. Physics, of course, tells us that a suit like this is pretty much impossible. Except that they actually exist. Granted, the real-life suits don’t have the magic physics-defying powers of Mr. Wick’s suit, but if you have the cash, you can get a smart-looking suit that protects you from getting killed by a bullet.

Real Life, Part I

In the movies, the suits supposedly have Kevlar in them just like a real piece of ballistic body armor. The problem is, Kevlar is bulky. However, most of the real body armor you see — like a vest on a SWAT team operative — is made from Kevlar or similar ballistic fibers like Twaron, Goldflex, or Dyneema. They also have plates made of metal or ceramic. Continue reading “The Real John Wick-Style Bullet Proof Suit” →

Share Your Projects: Take Pictures

April 7, 2023 by 38 Comments

Information is diesel for a hacker’s engine, and it’s fascinating how much can happen when you share what you’re working on. It could be a pretty simple journey – say, you record a video showing you fixing your broken headphones, highlighting a particular trick that works well for you. Someone will see it as an entire collection of information – “if my headphones are broken, the process of fixing them looks like this, and these are the tools I might need”. For a newcomer, you might be leading them to an eye-opening discovery – “if my headphones are broken, it is possible to fix them”.

There’s a few hundred different ways that different hackers use for project information sharing – and my bet is that talking through them will help everyone involved share better and easier. Let’s start talking about pictures – perhaps, the most powerful tool in a hacker’s arsenal. I’ll tell you about all the picture-taking hacks and guidelines I’ve found, go into subjects like picture habits and simple tricks, and even tell you what makes Hackaday writers swoon!

To start with, here’s a picture of someone hotwiring a car. This one picture conveys an entire story, and a strong one.

Continue reading “Share Your Projects: Take Pictures” →

This Week In Security: Cookie Monster, CyberGhost, NEXX, And Dead Angles

April 7, 2023 by 5 Comments

“Operation Cookie Monster” ranks as one of the best code names in recent memory. And it’s apropo, given what exactly went down. Genesis Market was one of those marketplaces where criminals could buy and sell stolen credentials. This one was a bit extra special.

Websites and services are getting better about detecting logins from unexpected computers. Your Google account suddenly logs in from a new computer, and a two-factor authentication challenge launches. Why? Your browser is missing a cookie indicating you’ve logged in before. But there’s more. Providers have started rolling out smart analytics that check for IP address changes and browser fingerprints. Your mix of time zone, user string, installed fonts, and selected language make a pretty unique identifier. So sites like Genesis offer Impersonation-as-a-Service (IMPaaS), which is session hijacking for the modern age.

A victim computer gets owned, and credentials are collected. But so are cookies and a browser fingerprint. Then a criminal buyer logs in, and runs a virtual browser with all that collected data. Run through a proxy to get a IP that is geolocated close enough to the victim, and Mr. Bad Guy has a cloned machine with all accounts intact.

And now back to Operation Cookie Monster, a multi-organization takedown of Genesis. It’s apparently a partial takedown, as the latest word is that the site is still online on the Tor network. But the conventional domains are down, and something like eight million credentials have been captured and added to the Have I Been Pwned database.

Another researcher team, Sector 7, has been working the case with Dutch authorities, and has some interesting details. The vector they cover was a fake activation crack for an antivirus product. Ironic. There are several extensions that get installed on the victim computer, and one of the most pernicious is disguised as Google Drive. This extension looks for a Command and Control server, using Bitcoin as DNS. A hardcoded Bitcoin address is polled for its latest transaction, and the receiving address is actually an encoded domain name, you-rabbit[.]com as of the latest check.

This extension will look for and rewrite emails that might be warning the victim about compromise. Get an email warning about a cryptocurrency withdrawal? It modifies it in the browser to be a sign-in warning. It also allows Genesis customers to proxy connections through the victim’s browser, bypassing IP address security measures. Continue reading “This Week In Security: Cookie Monster, CyberGhost, NEXX, And Dead Angles” →