{"rowid": 70, "title": "Bringing Your Code to the Streets", "contents": "\u2014 or How to Be a Street VJ\nOur amazing world of web code is escaping out of the browser at an alarming rate and appearing in every aspect of the environment around us. Over the past few years we\u2019ve already seen JavaScript used server-side, hardware coded with JavaScript, a rise of native style and desktop apps created with HTML, CSS and JavaScript, and even virtual reality (VR) is getting its fair share of front-end goodness.\nYou can go ahead and play with JavaScript-powered hardware such as the Tessel or the Espruino to name a couple. Just check out the Tessel project page to see JavaScript in the world of coffee roasting or sleep tracking your pet. With the rise of the internet of things, JavaScript can be seen collecting information on flooding among other things. And if that\u2019s not enough \u2018outside the browser\u2019 implementations, Node.js servers can even be found in aircraft!\nI previously mentioned VR and with three.js\u2019s extra StereoEffect.js module it\u2019s relatively simple to get browser 3D goodness to be Google Cardboard-ready, and thus set the stage for all things JavaScript and VR. It\u2019s been pretty popular in the art world too, with interactive works such as Seb Lee-Delisle\u2019s Lunar Trails installation, featuring the old arcade game Lunar Lander, which you can now play in your browser while others watch (it is the web after all). The Science Museum in London held Chrome Web Lab, an interactive exhibition featuring five experiments, showcasing the magic of the web. And it\u2019s not even the connectivity of the web that\u2019s being showcased; we can even take things offline and use web code for amazing things, such as fighting Ebola.\nOne thing is for sure, JavaScript is awesome. Hell, if you believe those telly programs (as we all do), JavaScript can even take down the stock market, purely through the witchcraft of canvas! Go JavaScript!\nNow it\u2019s our turn\nSo I wanted to create a little project influenced by this theme, and as it\u2019s Christmas, take it to the streets for a little bit of party fun! Something that could take code anywhere. Here\u2019s how I made a portable visual projection pack, a piece of video mixing software and created some web-coded street art.\nStep one: The equipment\nYou will need:\n\nOne laptop: with HDMI output and a modern browser installed, such as Google Chrome.\nOne battery-powered mini projector: I\u2019ve used a Texas Instruments DLP; for its 120 lumens it was the best cost-to-lumens ratio I could find.\nOne MIDI controller (optional): mine is an ICON iDJ as it suits mixing visuals. However, there is more affordable hardware on the market such as an Akai LPD8 or a Korg nanoPAD2. As you\u2019ll see in the article, this is optional as it can be emulated within the software.\nA case to carry it all around in.\n\n\nStep two: The software\nThe projected visuals, I imagined, could be anything you can create within a browser, whether that be simple HTML and CSS, images, videos, SVG or canvas. The only requirement I have is that they move or change with sound and that I can mix any one visual into another.\nYou may remember a couple of years ago I created a demo on this very site, allowing audio-triggered visuals from the ambient sounds your device mic was picking up. That was a great starting point \u2013 I used that exact method to pick up the audio and thus the first requirement was complete. If you want to see some more examples of visuals I\u2019ve put together for this, there\u2019s a showcase on CodePen.\nThe second requirement took a little more thought. I needed two screens, which could at any point show any of the visuals I had coded, but could be mixed from one into the other and back again. So let\u2019s start with two divs, both absolutely positioned so they\u2019re on top of each other, but at the start the second screen\u2019s opacity is set to zero.\nNow all we need is a slider, which when moved from one side to the other slowly sets the second screen\u2019s opacity to 1, thereby fading it in.\nSee the Pen Mixing Screens (Software Version) by Rumyra (@Rumyra) on CodePen.\nMixing Screens (CodePen)\n\nAs you saw above, I have a MIDI controller and although the software method works great, I\u2019d quite like to make use of this nifty piece of kit. That\u2019s easily done with the Web MIDI API. All I need to do is call it, and when I move one of the sliders on the controller (I\u2019ve allocated the big cross fader in the middle for this), pick up on the change of value and use that to control the opacity instead.\nvar midi, data;\n// start talking to MIDI controller\nif (navigator.requestMIDIAccess) {\n  navigator.requestMIDIAccess({\n    sysex: false\n  }).then(onMIDISuccess, onMIDIFailure);\n} else {\n  alert(\u201cNo MIDI support in your browser.\u201d);\n}\n\n// on success\nfunction onMIDISuccess(midiData) {\n  // this is all our MIDI data\n  midi = midiData;\n\n  var allInputs = midi.allInputs.values();\n  // loop over all available inputs and listen for any MIDI input\n  for (var input = allInputs.next(); input && !input.done; input = allInputs.next()) {\n    // when a MIDI value is received call the onMIDIMessage function\n    input.value.onmidimessage = onMIDIMessage;\n  }\n}\n\nfunction onMIDIMessage(message) {\n  // data comes in the form [command/channel, note, velocity]\n  data = message.data;\n\n  // Opacity change for screen. The cross fader values are [176, 8, {0-127}]\n  if ( (data[0] === 176) && (data[1] === 8) ) {\n    // this value will change as the fader is moved\n    var opacity = data[2]/127;\n    screenTwo.style.opacity = opacity;\n  }\n}\n\nThe final code was slightly more complicated than this, as I decided to switch the two screens based on the frequencies of the sound that was playing, and use the cross fader to depict the frequency threshold value. This meant they flickered in and out of each other, rather than just faded. There\u2019s a very rough-and-ready first version of the software on GitHub.\nPhew, Great! Now we need to get all this to the streets!\nStep three: Portable kit\nDid you notice how I mentioned a case to carry it all around in? I wanted the case to be morphable, so I could use the equipment from it too, a sort of bag-to-usherette-tray-type affair. Well, I had an unused laptop bag\u2026\n\nI strengthened it with some MDF, so when I opened the bag it would hold like a tray where the laptop and MIDI controller would sit. The projector was Velcroed to the external pocket of the bag, so when it was a tray it would project from underneath. I added two durable straps, one for my shoulders and one round my waist, both attached to the bag itself. There was a lot of cutting and trimming. As it was a laptop bag it was pretty thick to start and sewing was tricky. However, I only broke one sewing machine needle; I\u2019ve been known to break more working with leather, so I figured I was doing well. By the way, you can actually buy usherette trays, but I just couldn\u2019t resist hacking my own :)\nStep four: Take to the streets\nFirst, make sure everything is charged \u2013 everything \u2013 a lot! The laptop has to power both the MIDI controller and the projector, and although I have a mobile phone battery booster pack, that\u2019ll only charge the projector should it run out. I estimated I could get a good hour of visual artistry before I needed to worry, though.\nI had a couple of ideas about time of day and location. Here in the UK at this time of year, it gets dark around half past four, so I could easily head out in a city around 5pm and it would be dark enough for the projections to be seen pretty well. I chose Bristol, around the waterfront, as there were some interesting locations to try it out in. The best was Millennium Square: busy but not crowded and plenty of surfaces to try projecting on to.\nMy first time out with the portable audio/visual pack (PAVP as it will now be named) was brilliant. I played music and projected visuals, like a one-woman band of A/V!\n\n\nYou might be thinking what the point of this was, besides, of course, it being a bit of fun. Well, this project got me to look at canvas and SVG more closely. The Web MIDI API was really interesting; MIDI as a data format has some great practical uses. I think without our side projects we may not have all these wonderful uses for our everyday code. Not only do they remind us coding can, and should, be fun, they also help us learn and grow as makers.\nMy favourite part? When I was projecting into a water feature in Millennium Square. For those who are familiar, you\u2019ll know it\u2019s like a wall of water so it produced a superb effect. I drew quite a crowd and a kid came to stand next to me and all I could hear him say with enthusiasm was, \u2018Oh wow! That\u2019s so cool!\u2019\nYes\u2026 yes, kid, it was cool. Making things with code is cool.\nMassive thanks to the lovely Drew McLellan for his incredibly well-directed photography, and also Simon Johnson who took a great hand in perfecting the kit while it was attached.", "year": "2015", "author": "Ruth John", "author_slug": "ruthjohn", "published": "2015-12-06T00:00:00+00:00", "url": "https://24ways.org/2015/bringing-your-code-to-the-streets/", "topic": "code"}