holiday-node-sin-mdns.js

#! /usr/local/bin/node

// ---[ Dependencies ]------------------------------------------------------------------------------

var dgram = require("dgram");
var mdns = require("mdns");

// ---[ Config ]------------------------------------------------------------------------------------

var mdnsTimeout = 20000; // ms

var serverHost;
var serverPort;
var numLights = 50;

var pi = Math.PI;
var pi2 = Math.PI * 2;

var radsPerLight = pi/numLights;

var fps = 24;

var radsPerTick = 0.03;

// ---[ Setup ]-------------------------------------------------------------------------------------

var radR = 0.0;
var radG = 0.3 * pi;
var radB = 0.7 * pi;

// Construct a blank buffer
var message = [];

for (var i = 0; i< 10 + (3*numLights); i++) {
	message.push(0);
}

var messageBuffer = new Buffer(message);

// ---[ Message generation ]------------------------------------------------------------------------

// I know this is crap :D

function updateMessage() {

	for (var j = 0; j < numLights; j++) {
		var i = 10+(j*3);
		var rads = radsPerLight * j;

		messageBuffer[i] = Math.round(127.5 + (Math.sin(radR + (radsPerLight * j)) * 127.5));
		messageBuffer[i+1] = Math.round(127.5 + (Math.sin(radB + (radsPerLight * j)) * 127.5));
		messageBuffer[i+2] = Math.round(127.5 + (Math.sin(radG + (radsPerLight * j)) * 127.5));
	}
}

// ---[ Message sending ]---------------------------------------------------------------------------

var client = dgram.createSocket("udp4");

function sendBuffer() {
	client.send(messageBuffer,0,messageBuffer.length, serverPort,serverHost, function(err,bytes){
		if (err) throw err;
	});
}

// ---[ Animation loop ]----------------------------------------------------------------------------

function tick() {
	radR += radsPerTick;
	if (radR > pi2) 
		radR -= pi2;

	radG += radsPerTick / 2;
	if (radG > pi2) 
		radG -= pi2;

	radB += radsPerTick / 4;
	if (radB > pi2)
		radB -= pi2;

	updateMessage();
	sendBuffer();
}

var interval ;

function startAnimating() {
	clearInterval(interval);
	interval = setInterval(tick,1000/fps);
}

// ---[ MDNS lookup - lazy and ugly ]---------------------------------------------------------------

console.log("Looking for your Holiday...");

var browser = mdns.createBrowser(mdns.udp("secretapi"));

browser.on('serviceUp', function(service) {
	serverPort = service.port;
	serverHost = service.host;
	console.log("Found your holiday at",serverHost,"port", serverPort);
	clearTimeout(timeout);
	startAnimating();
});

browser.on('serviceDown', function(service) {
	process.exit(0); // Might as well.
});

var timeout = setTimeout(function(){
	console.log("Could not find a Holiday :(");
	process.exit(1);
}, mdnsTimeout);

browser.start();