I recently developed an application for a museum running on a TILE display from Displax.
In order to get this up and running I needed to create a node.js server and websocket connection. Recent examples of this are hard to find online, so I want to share my code for anyone in the same situation, hopefully this saves you some time 🙂
First you must have installed a server and node.js
Then install the packages needed through terminal/command prompt:
In your html file include this:
https://cdn.socket.io/4.7.5/socket.io.min.js
Now you need to create a server file, let’s call it “server.js”:
var osc = require(‘osc’);
const express = require(‘express’);
const { createServer } = require(‘node:http’);
const { Server } = require(‘socket.io’);
const app = express();
const server = createServer(app);
var socket;
const io = require(“socket.io”)(server, {cors:{origin: “*”,methods: [“GET”, “POST”]}});
//Listen to the TUIO data
const udpPort = new osc.UDPPort({
localAddress: “127.0.0.1”,
localPort: 3333,
metadata: true
});
//Listen/send on port 3000 or 5000
server.listen(3000, () => {
console.log(‘Server running at http://localhost:3000’);
});
io.on(‘connection’, function (_socket) {
socket = _socket;
socket.on(‘config’, function (obj) {
console.log(‘config’, obj);
});
});
// Listen for incoming OSC bundles.
udpPort.on(“bundle”, function (oscBundle){
if(socket && oscBundle.packets.length > 2) socket.emit(‘message’, oscBundle);//only send TUIO v1.1
});
// Open the socket.
udpPort.open();
Now for connecting in the front-end, we need this script:
const socket = io(_address);//, {withCredentials: true}
socket.on(‘error’, function(){
console.log(“Error connecting!”);
});
socket.on(‘connect’, function(){
console.log(“Server connected”);
socket.emit(‘config’, {server:{port: 3333,host: ‘127.0.0.1’},client: {port: 3334,host: ‘127.0.0.1’}});
});
socket.on(‘message’, function(oscBundle){
});
}
//Init
WSConnection(“http://127.0.0.1:3000”);//or port 5000
To start the server open terminal and cd into the server.js folder and enter:
node server.js
Now your have a running node.js server and a front-end that listens to any TUIO objects being sent through the server.
In order to test you can download the “TUIOSimulator.app” from here:
https://github.com/gregharding/TUIOSimulator
When above works you are facing the next challenge. Depending on the hardware and software you are using, TUIO objects can often be a little unreliable. Sometimes events are fired too slowly, so you think an object is removed from the display. So I made some custom work arounds for these scenarios. In my example I’m using both touch and object recognition, so I have to use both “tuio/2Dcur” and “tuio/2Dobj”.
This is my “message” function:
var _l = 0, _id = 0, _numAlive = 0, _cursorId = 0;
var _v = “”;
socket.on(‘message’, function(oscBundle){
_l = oscBundle.packets.length;
for(var i=0;i<_l;i++){
if(oscBundle.packets[i].address == “/tuio/2Dcur”){
_v = oscBundle.packets[i].args[0].value;
if(_v == “alive”){
//Find alive cursors
_numAlive = oscBundle.packets[i].args.length – 1;
_alive = [];
for(var l=0;l<_numAlive;l++){
_cursorId = oscBundle.packets[i].args[l+1].value%100;
_alive.push(_cursorId);
if(_aliveCursors.indexOf(_cursorId) == -1){
console.log(“Add cursor”,_cursorId);
_aliveCursors.push(_cursorId);
_cursors[_cursorId] = new TuioObj(_cursorId,false);
}
else _cursors[_cursorId]._removed = false;//keep alive (if set to be removed on next render)
}
//Find old cursors not alive anymore
_numAlive = _aliveCursors.length;
for(var l=0;l<_numAlive;l++){
if(_alive.indexOf(_aliveCursors[l]) == -1){
_id = _aliveCursors[l];
if(_cursors[_id]._removed){
console.log(“Destroy cursor”, _id);
_cursors[_id].destroy();
delete _cursors[_id];
_aliveCursors.splice(l,1);
_numAlive–;
l = 0;
}
else{
//console.log(“Remove cursor”, _id);
_cursors[_id]._removed = true;
}
}
}
}
else if(_v == “set”){
_cursorId = oscBundle.packets[i].args[1].value%100;
if(_aliveCursors.indexOf(_cursorId) != -1) _cursors[_cursorId].setXY(oscBundle.packets[i].args[2].value * _appW,oscBundle.packets[i].args[3].value * _appH);
else console.log(“Cursor not found!”, _cursorId);
}
}
else if(oscBundle.packets[i].address == “/tuio/2Dobj”){
_v = oscBundle.packets[i].args[0].value;
if(_v == “alive”){
//Find alive cursors
_numAlive = oscBundle.packets[i].args.length – 1;
_alive = [];
for(var l=0;l<_numAlive;l++){
_cursorId = oscBundle.packets[i].args[l+1].value%100;
_alive.push(_cursorId);
if(_aliveTags.indexOf(_cursorId) == -1){
console.log(“Add tag”,_cursorId);
_aliveTags.push(_cursorId);
_tags[_cursorId] = new TuioObj(_cursorId,true);
}
else _tags[_cursorId]._removed = false;//keep alive (if set to be removed on next render)
}
//Find old cursors not alive anymore
_numAlive = _aliveTags.length;
for(var l=0;l<_numAlive;l++){
if(_alive.indexOf(_aliveTags[l]) == -1){
_id = _aliveTags[l];
if(_tags[_id]._removed){
console.log(“Destroy tag”, _id);
_tags[_id].destroy();
delete _tags[_id];
_aliveTags.splice(l,1);
_numAlive–;
l = 0;
}
else{
//console.log(“Remove tag”, _id);
_tags[_id]._removed = true;
}
}
}
}
else if(_v == “set”){
//console.log(“Tag static id:”, oscBundle.packets[i].args[2].value)
_cursorId = oscBundle.packets[i].args[1].value%100;
if(_aliveTags.indexOf(_cursorId) != -1) _tags[_cursorId].setXYR(oscBundle.packets[i].args[3].value * _appW,oscBundle.packets[i].args[4].value * _appH,oscBundle.packets[i].args[5].value);
else console.log(“Tag not found!”, _cursorId);
}
}
}
});
For each TUIO object, either a Tag or Touch, I am using this TuioObj, here’s a simplified version of mine:
var _this = this;
_this._removed = false;//TUIO “alive” events are not reliable and often remove an object only to add it instantly again!
//Touch (x and y coordinate)
_this.setXY = function(x,y){}
//Tag (x and y coordinate and rotation value)
_this.setXYR = function(x,y,r){}
//Destroy (remove DOM elements, event listeners etc.)
_this.destroy = function(){}
}
Of course many more features, like idle handling, smooth movement (check my post on lerp) and distance measurement (for click handling etc.) can be added, but now you should have a template to get you started.
