Digital Painting On An IPad With Real Brushes

Drawing tablets are a great way to make digital art, and iPads and other tablets are similarly popular in this area. However, they all typically involve using some sort of special stylus for input. [Richard Greene] developed another method, with Light Strokes for the iPad letting one “paint” with real paint brushes instead!

The system uses a Fresnel prism in view of the iPad’s camera. This allows the camera to see only the parts of a paint brush, sponge, or other implement, as they make contact with the surface of the prism itself. This is via the principle known as total internal reflection.

Thus, simply wetting a paintbrush, sponge, or even a finger, allows one to paint quite authentically on the surface of the prism. The corresponding Light Strokes app on the iPad turns this into the pretty pixels of your creation. The app also allows one to experiment with all manner of fancy brush effects, too.

The build requires some finesse, with the lamination of the special Fresnel film onto glass using liquid optically clear adhesive, or LOCA. A series of mirrors are then assembled in an enclosure, allowing the iPad to be mounted with the camera having a good view of the glass painting area.

The project takes advantage of a simple physical effect in order to create a great artistic tool. Alternatively, if you prefer to draw directly, consider whipping up your own screen-based drawing tablet. Video after the break.

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One-Percenter Mods For Premium Apple Pencil Usability

At $129 USD, Apple certainly do sell a very expensive “pencil”. Despite the high cost of entry, [Eric] identified several shortcomings and set about solving them himself with a few choice mods.

The first concern is the excessively slippery surface finish, that could lead to the expensive device being dropped and damaged. [Eric] starts by creating a special tool to help handle the pencil during the refinishing process. He highlights how key this is to getting a good final result, without fingerprints or other flaws ruining the finish. With the manipulator ready, the pencil is then given a wipe down with wax and grease remover prior to a dusting of a translucent spray paint. The finish is poor, however, and [Eric] instead elects to try again with a plastic primer first. A series of tinted clear coats are chased with a urethane clear topcoat for a hardy, grippier surface texture.

The final mod concerns the tip. It’s lathed down in a power drill to give a shape more akin to the ballpoint pens [Eric] is used to sketching with. Additionally, the tip is dyed black with a Sharpie marker and a heat gun, to help it contrast better when sketching on a white screen.

These mods may seem trivial to a casual user, but for a designer who draws for a living, usability is key. The striking orange finish is just a bonus. We don’t see too many stylus mods, but with the increased popularity of tablets, we’re sure to see more down the road. If you’ve got one, be sure to drop us a line! Video after the break.

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Netbooks: The Form Factor Time Forgot

Long ago, before smartphones were ubiquitous and children in restaurants were quieted with awful games on iPads, there was a beautiful moment. A moment in which the end user could purchase, at a bargain price, an x86 computer in a compact, portable shell. In 2007, the netbook was born, and took the world by storm – only to suddenly vanish a few years later. What exactly was it that made netbooks so great, and where did they go?

A Beautiful Combination

An Asus EEE PC shown here running Linux. You could run anything on them! Because they were real, full-fat computers. No locked down chipsets or BIOS. Just good, clean, x86 fun.

The first machine to kick off the craze was the Asus EEE PC 701, inspired by the One Laptop Per Child project. Packing a 700Mhz Celeron processor, a small 7″ LCD screen, and a 4 GB SSD, it was available with Linux or Windows XP installed from the factory. With this model, Asus seemed to find a market that Toshiba never quite hit with their Libretto machines a decade earlier. The advent of the wireless network and an ever-more exciting Internet suddenly made a tiny, toteable laptop attractive, whereas previously it would have just been a painful machine to do work on. The name “netbook” was no accident, highlighting the popular use case — a lightweight, portable machine that’s perfect for web browsing and casual tasks.

But the netbook was more than the sum of its parts. Battery life was in excess of 3 hours, and the CPU was a full-fat x86 processor. This wasn’t a machine that required users to run special cut-down software or compromise on usage. Anything you could run on an average, low-spec PC, you could run on this, too. USB and VGA out were available, along with WiFi, so presentations were easy and getting files on and off was a cinch. It bears remembering, too, that back in the Windows XP days, it was easy to share files across a network without clicking through 7 different permissions tabs and typing in your password 19 times.

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Classic Macintosh Gets An IPad Infusion

We know the classic Mac fans in the audience won’t be happy about this one, but the final results are simply too clean to ignore. With a laser-cut adapter and a little custom wiring, [Travis DeRose] has come up with a repeatable way to modernize a Compact Macintosh (Plus, SE, etc) by swapping out all of its internals for an iPad mini.

He goes over the whole process in the video after the break, while being kind enough to spare our sensitive eyes from having to see the Mac’s enclosure stripped of its original electronics. We’ll just pretend hope that the computer was so damaged that repair simply wasn’t an option.

Anyway, with a hollow Mac in your possession, you can install the adapter that allows the iPad to get bolted in place of the original CRT monitor. You won’t be able to hit the Home button anymore, but otherwise it’s a very nice fit.

Those with some first hand iPad experience might be wondering how you wake the tablet up once the Mac is all buttoned back up. That’s an excellent question, and one that [Travis] wrestled with for awhile. In the end he came up with a very clever solution: he cuts into a charging cable and splices in a normally-closed momentary push button. Pushing the button essentially “unplugs” the iPad for a second, which just so happens to wake it up. It’s an elegant solution that keeps you from having to make any modifications to that expensive piece of Apple hardware.

If there’s one thing we’re not thrilled with, it’s the empty holes left behind where the ports, switches, and floppy drive were removed. As we’ve seen in the past, you can simply cut the ports off of a motherboard and glue them in place to make one of these conversions look a little more convincing. If you’re going to do it, might as well go all the way.

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Put Those IPad Displays To Work With This EDP Adapter

Regardless of how you might feel about Apple and the ecosystem they’ve cultured over the years, you’ve got to give them some credit in the hardware department. Their “Retina” displays are a perfect example; when they brought the 2,048 by 1,536 panel to the iPad 3, the technology instantly became the envy of every tablet owner. But what if you want to use one of these gorgeous screens outside of Apple’s walled garden?

As it turns out, there are a number of options out there to use these screens on other devices, but [Arthur Jordan] wasn’t quite happy with any of them. So he did what any self respecting hacker would do, and built his own adapter for iPad 3 and 4 screens. Not that he did it completely in the dark; his design is based on the open source Adafruit Qualia driver, which in turn was based on research done by [Mike’s Mods]. A perfect example of the open source community at work.

The resulting board allows you to connect the Retina display from the iPad 3 or 4 to any device that features Embedded DisplayPort (eDP). Rather than put a dedicated port on his board, [Arthur] just left bare pads where you can solder up whatever interface method your particular gadget might use. In his case, he wanted to hook it up to an x86 UP Core SBC, so he even came up with a seperate adapter that breaks out that board’s diminutive display connector to something that can be soldered by hand.

So what’s different between the board [Arthur] developed and Adafruit’s Qualia? Primarily its been made smaller by deleting the DisplayPort connectors in favor of those bare pads, but he’s also dumped the backlight control hardware and 3.3V regulator that in his experience hasn’t been necessary with the eDP devices he’s worked with. So if space is a concern in your build, this version might be what you’re after.

We’ve seen other Retina display adapters in the past, and of course the iPad isn’t the only high-end device that’s had a screen good enough to reuse on its own. The lesson here is that if you put a must-have feature in your product, don’t be surprised when some hacker comes along and figures out how to liberate it for their own purposes.

Faster Computers Lead To Slower Experiences?

Ever get that funny feeling that things aren’t quite what they used to be? Not in the way that a new washing machine has more plastic parts than one 40 years its senior. More like “my laptop can churn through hundreds of gigaflops, but when I scroll it doesn’t feel great.” That perception of smoothness might be based on a couple factors, including system latency. A couple years ago [danluu] had that feeling too and measured the latency of “devices I’ve run into in the past few months” (based on this list, he lives a more interesting life than we do). It turns out his hunch was objectively correct. What he wrote was a wonderful deep dive into how and why a wide variety of devices work and the hardware and software contributors to latency.

Let’s be clear about what “latency” means in this context. [danluu] was checking the time between a user input and some response on screen. For desktop systems he measured a keystroke, for mobile devices scrolling a browser. If you’re here on Hackaday (or maybe at a Vintage Computer Festival) the cause of the apparent contradiction at the top of the charts might be obvious.

Q: Why are some older systems faster than devices built decades later? A: The older systems just didn’t do much! Instead of complex multi-tasking operating systems doing hundreds of things at once, the CPU’s entire attention was bent on whatever user process was running. There are obvious practical drawbacks here but it certainly reduces context switching!

In some sense this complexity that [danluu] describes is at the core of how we solve problems with programming. Writing code is all about abstraction. While it’s true that any program could be written directly in machine code and customized to an individual machine’s hardware configuration, it would be pretty inconvenient for both developer and user. So over time layers of sugar have been added on top to hide raw hardware behind nicer interfaces written in higher-level programming languages.

And instead of writing every program to target exact hardware configurations there is a kernel to handle the lowest layers, then layers adding hotplug systems, power management, pluggable module and driver infrastructure, and more. When considering solutions to a programming problem the approach is always recursive: you can solve the problem, or add a layer of abstraction and reframe it. Enough layers of the latter makes the former trivial. But it’s abstractions all the way down.

[danluu]’s observation is that we’re just now starting to curve back around and hit low latency again, but this time by brute force! Modern solutions to latency largely look like increasingly exotic display technologies and complex optimizations which reach from UI draw functions all the way down to the silicon, not removing software and system infrastructure. It turns out the benefits of software complexity in terms of user experience and ease of development are worth it most of the time.

For a very tangible illustration of latency as applied to touchscreen devices, check out the Microsoft Research video after the break (linked to in [danluu]’s piece).

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Wonderful IPad Mini 2 Home Made Spiral Notebook Case

Part of the joy of hacking is the joy of discovery, of seeing how things go right as well as wrong. That’s one cool thing about this iPad Mini 2 case build by [Eric Strebel]: in the video, he details the things that went wrong as well as those that went right. For instance, he used glue on one version that melted the foam core he built the iPad holder from. The end product is wonderful, though. It combines an iPad Mini 2 case and a spiral-bound notebook so you can use both digital and paper mediums, with the iPad cleverly hidden behind a panel that both protects it and turns the screen off when not in use.

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