Update public/js/nodecopter-stream.js

reword comment again
(I'm really just playing around with github online editing)

.gitignore

@@ -1,3 +1,2 @@
 node_modules
 .*.swp
-.DS_Store

.jshintrc

@@ -1,32 +0,0 @@
-{
-    "es5" : true,
-
-    "browser" : false,
-    "boss" : true,
-    "curly": true,
-    "debug": false,
-    "devel": true,
-    "eqeqeq": true,
-    "evil": false,
-    "forin": true,
-    "immed": true,
-    "indent": 4,
-    "jquery": true,
-    "laxbreak": false,
-    "laxcomma": true,
-    "newcap": true,
-    "noarg": false,
-    "noempty": true,
-    "nonew": true,
-    "nomen": false,
-    "onevar": true,
-    "plusplus": false,
-    "regexp": false,
-    "trailing": true,
-    "undef": true,
-    "sub": false,
-    "strict": true,
-    "globalstrict": true,
-    "white": true,
-    "node" : true
-}

History.md

@@ -1,33 +0,0 @@
-0.1.0 / 2012-10-20
-==================
-
-  * Initial version, unreleased
-
-0.2.0 / 2012-10-20
-==================
-
-  * released as npm package dronestream
-
-1.0.0 / 2012-12-15
-==================
-
-  * add support for multiple browser clients
-  * add support for browser reloads
-  * reconnect to drone on failure
-  * add support for bare http sockers
-  * remove express dependency
-  * export as a module
-  * added examples for using in other applications
-
-1.0.1 / 2012-12-16
-==================
-
-  * update documentation
-  * add changelog
-
-1.0.2 / 2012-12-27
-==================
-
-  * use requestAnimationFrame() for rendering video frames
-  * cleaned up express example
-  * update ar-drone and buffy dependencies to latest versions

README.md

@@ -10,27 +10,6 @@ This code uses web-sockets and the incredibly awesome
 [Broadway.js](https://github.com/mbebenita/Broadway) to render the video frames
 in your browser using a WebGL canvas.
 
-## How to use
-
-Please see the http.createServer and Express 3.0 examples in the 'examples' dir.
-You attach the stream to your server like this:
-```javascript
-// in node:
-//
-// note that the 'server' object points to a server instance and NOT an express app.
-require("dronestream").listen(server); 
-```
-
-We serve the client in the same manner as Socket.IO. Add a reference to 
-**/dronestream/nodecopter-client.js** in your template. Then attach the stream to a DOM node:
-```html
-<!-- on the client -->
-<script src="/dronestream/nodecopter-client.js"></script>
-<script>
-  // video canvas will auto-size to the DOM-node, or default to 640*360 if no size is set.
-  new NodecopterStream(document.getElementById("droneStream"));
-</script>
-```
 
 ## How it works
 
@@ -43,9 +22,10 @@ In the browser broadway takes care of the rendering of the WebGL canvas.
 
 ## Status
 
-Node-dronestream has gained some stability in the last release. It attempts 
-to recover lost connections to the drone, and it handles multiple clients, 
-disconnections, etc. See "How to use" for API.
+For this release I was exclusively interested in the lowest possible latency.
+There is no error handling for the websockets, the connection to the drone or
+the video player what-so-ever. This may come eventually, or may not. I think it
+is enough to be used as a starting point for your own integration.
 
 ## Thanks
 
@@ -65,9 +45,3 @@ disconnections, etc. See "How to use" for API.
 - Brian Leroux for being not content with the original solution and for
   cleaning up the predecessor, nodecopter-stream.
 
-- @karlwestin for picking up where I was to lazy to actually make this usable.
-
-## Demo
-
-Watch @felixge demoing node-dronestream live at german user group cgnjs:
-http://www.youtube.com/watch?v=nwGNNMJt4mE&t=19m52

app.js

@@ -0,0 +1,82 @@
+'use strict';
+/**
+ * Module dependencies.
+ */
+
+var express = require('express')
+  , routes = require('./routes')
+  , http = require('http')
+  , path = require('path')
+  , app = express()
+  , server = http.createServer(app)
+  , WebSocketServer = require('ws').Server
+  , wss = new WebSocketServer({server: server})
+  , sockets = []
+  , Parser = require('./lib/PaVEParser')
+  , arDrone = require('ar-drone')
+  ;
+
+function init() {
+    var tcpVideoStream = new arDrone.Client.PngStream.TcpVideoStream({timeout: 4000})
+      , p = new Parser();
+
+    console.log("Connecting to stream");
+
+    tcpVideoStream.connect(function () {
+        tcpVideoStream.pipe(p);
+    });
+
+    tcpVideoStream.on("error", function(err) {
+      console.log("There was an error: %s", err.message);
+      tcpVideoStream.end();
+      tcpVideoStream.emit("end");
+      init();
+    });
+
+    p.on('data', function (data) {
+      sockets.forEach(function(socket) {
+        socket.send(data, {binary: true});
+      });
+    });
+}
+init();
+
+wss.on('connection', function (socket) {
+  sockets.push(socket);
+
+  socket.on("close", function() {
+    console.log("Closing socket");
+    sockets = sockets.filter(function(el) {
+      return el !== socket;
+    });
+  });
+});
+
+
+app.configure(function () {
+    app.set('port', process.env.PORT || 3000);
+    app.set('views', __dirname + '/views');
+    app.set('view engine', 'jade', { pretty: true });
+    app.use(express.favicon());
+    app.use(express.logger('dev'));
+    app.use(express.bodyParser());
+    app.use(express.methodOverride());
+    app.use(app.router);
+    app.use(express.static(path.join(__dirname, 'public')));
+});
+
+app.configure('development', function () {
+    app.use(express.errorHandler());
+    app.locals.pretty = true;
+});
+
+
+app.get('/', routes.index);
+
+if (module.parent) {
+    module.exports = server;
+} else {
+    server.listen(app.get('port'), function () {
+        console.log("Express server listening on port " + app.get('port'));
+    });
+}

build_client

@@ -1,3 +0,0 @@
-#!/bin/bash
-
-cat dist/vendor/broadway/sylvester.js dist/vendor/broadway/glUtils.js dist/vendor/broadway/util.js dist/vendor/broadway/avc-codec.js dist/vendor/broadway/avc.js dist/vendor/broadway/canvas.js dist/nodecopter-stream.js > dist/nodecopter-client.js

dist/nodecopter-stream.js

@@ -1,105 +0,0 @@
-/*jshint browser:true */
-/*global Avc:true, YUVWebGLCanvas: true, Size: true, requestAnimationFrame:true */
-
-/* requestAnimationFrame polyfill: */
-(function (window) {
-    'use strict';
-    var lastTime = 0,
-        vendors = ['ms', 'moz', 'webkit', 'o'],
-        x,
-        length,
-        currTime,
-        timeToCall;
-
-    for (x = 0, length = vendors.length; x < length && !window.requestAnimationFrame; ++x) {
-        window.requestAnimationFrame = window[
-            vendors[x] + 'RequestAnimationFrame'
-        ];
-        window.cancelAnimationFrame = window[
-            vendors[x] + 'CancelAnimationFrame'
-        ] || window[vendors[x] + 'CancelRequestAnimationFrame'];
-    }
-
-    if (!window.requestAnimationFrame) {
-        window.requestAnimationFrame = function (callback, element) {
-            currTime = new Date().getTime();
-            timeToCall = Math.max(0, 16 - (currTime - lastTime));
-            lastTime = currTime + timeToCall;
-            return window.setTimeout(function () {
-                callback(currTime + timeToCall);
-            }, timeToCall);
-        };
-    }
-
-    if (!window.cancelAnimationFrame) {
-        window.cancelAnimationFrame = function (id) {
-            clearTimeout(id);
-        };
-    }
-}(window));
-
-
-/* NodeCopterStream: */
-(function (window, document, undefined) {
-    'use strict';
-    var NS,
-        socket,
-        avc,
-        webGLCanvas;
-
-    function setupAvc() {
-        avc = new Avc();
-        avc.configure({
-            filter: 'original',
-            filterHorLuma: 'optimized',
-            filterVerLumaEdge: 'optimized',
-            getBoundaryStrengthsA: 'optimized'
-        });
-        avc.onPictureDecoded = handleDecodedFrame;
-    }
-
-    function handleNalUnits(message) {
-        avc.decode(new Uint8Array(message.data));
-    }
-
-    function handleDecodedFrame(buffer, width, height) {
-        requestAnimationFrame(function () {
-            var lumaSize = width * height,
-            chromaSize = lumaSize >> 2;
-            webGLCanvas.YTexture.fill(buffer.subarray(0, lumaSize));
-            webGLCanvas.UTexture.fill(buffer.subarray(lumaSize, lumaSize + chromaSize));
-            webGLCanvas.VTexture.fill(buffer.subarray(lumaSize + chromaSize, lumaSize + 2 * chromaSize));
-            webGLCanvas.drawScene();
-        });
-    }
-
-    function setupCanvas(div) {
-        var width = div.attributes.width ? div.attributes.width.value : 640,
-            height = div.attributes.height ? div.attributes.height.value : 360,
-            canvas = document.createElement('canvas');
-
-        canvas.width = width;
-        canvas.height = height;
-        canvas.style.backgroundColor = "#333333";
-        div.appendChild(canvas);
-
-        webGLCanvas = new YUVWebGLCanvas(canvas, new Size(width, height));
-    }
-
-
-    NS = function (div) {
-        setupCanvas(div);
-        setupAvc();
-
-        socket = new WebSocket(
-             'ws://' +
-            window.document.location.hostname + ':' +
-            window.document.location.port + '/dronestream'
-        );
-        socket.binaryType = 'arraybuffer';
-        socket.onmessage = handleNalUnits;
-    };
-
-    window.NodecopterStream = NS;
-
-}(window, document, undefined));

example/createServer/app.js

@@ -1,10 +0,0 @@
-var http = require("http"),
-    drone = require("../../index");
-
-
-var server = http.createServer(function(req, res) {
-  require("fs").createReadStream(__dirname + "/index.html").pipe(res);
-});
-
-drone.listen(server);
-server.listen(5555);

example/createServer/index.html

@@ -1,16 +0,0 @@
-<!doctype html>
-<html>
-<head>
-    <meta http-equiv="content-type" content="text/html; charset=utf-8">
-    <title>Stream as module</title>
-    <script src="/dronestream/nodecopter-client.js" type="text/javascript" charset="utf-8"></script>
-</head>
-<body>
-    <h1 id="heading">Stream through a normal require("http").createServer</h1>
-    <div id="droneStream" style="width: 640px; height: 360px">   </div>
-
-    <script type="text/javascript" charset="utf-8">
-        new NodecopterStream(document.getElementById("droneStream"));
-    </script>
-</body>
-</html>

example/express/app.js

@@ -1,33 +0,0 @@
-var express = require('express')
-  , routes = require('./routes')
-  , app = express()
-  , path = require('path')
-  , server = require("http").createServer(app)
-  ;
-
-
-app.configure(function () {
-    app.set('views', __dirname + '/views');
-    app.set('view engine', 'jade', { pretty: true });
-    app.use(express.favicon());
-    app.use(express.logger('dev'));
-    app.use(app.router);
-    app.use(express.static(path.join(__dirname, 'public')));
-});
-
-app.configure('development', function () {
-    app.use(express.errorHandler());
-    app.locals.pretty = true;
-});
-
-app.get('/', routes.index);
-
-/*
- * Important:
- *
- * pass in the server object to listen, not the express app
- * call 'listen' on the server, not the express app
- */
-// should be require("dronestream").listen(server);
-require("../../index").listen(server);
-server.listen(3000);

example/express/package.json

@@ -1,13 +0,0 @@
-{
-  "name": "dronestream-example",
-  "version": "0.1.1",
-  "dependencies": {
-    "express": "3.0.x",
-    "jade": "*"
-  },
-  "scripts": {
-    "start": "node app"
-  },
-  "author": "Bernhard K. Weisshuhn <bkw@codingforce.com>",
-  "license": "BSD"
-}

example/express/views/index.jade

@@ -1,22 +0,0 @@
-extends layout
-
-block append head
-  script(type='text/javascript', src='/dronestream/nodecopter-client.js')
-
--# for developing the client, use those url:s
--# script(type='text/javascript', src='/dronestream/vendor/broadway/sylvester.js')
--# script(type='text/javascript', src='/dronestream/vendor/broadway/glUtils.js')
--# script(type='text/javascript', src='/dronestream/vendor/broadway/util.js')
--# script(type='text/javascript', src='/dronestream/vendor/broadway/avc-codec.js')
--# script(type='text/javascript', src='/dronestream/vendor/broadway/avc.js')
--# script(type='text/javascript', src='/dronestream/vendor/broadway/canvas.js')
--# script(type='text/javascript', src='/dronestream/nodecopter-stream.js')
--# concatenated version of client
-
-
-block append bodyscripts
-  script
-    var copterStream = new NodecopterStream(document.querySelector('#dronestream'));
-
-block content
-  div#dronestream(width=640, height=360)

index.js

@@ -1 +0,0 @@
-module.exports = require("./lib/server");

lib/server.js

@@ -1,55 +0,0 @@
-/*
- * Drone Stream listen:
- * Takes a) a port number or b) a server object (node http or express, etc);
- */
-var staticDir = 'dronestream',
-    check = new RegExp('^/' + staticDir, 'i'),
-    dist = __dirname + '/../dist';
-
-module.exports.listen = function listen(server) {
-    'use strict';
-    var port, oldHandlers;
-
-    if (typeof server === 'number') {
-        port = server;
-        server = require('http').createServer();
-        server.listen(port);
-    }
-
-    /*
-     * Serving up the static files needed
-     */
-    oldHandlers = server.listeners('request').splice(0);
-
-    server.on('request', function (req, res) {
-        var i = 0;
-        if (handler(req, res)) {
-            return;
-        }
-
-        for (; i < oldHandlers.length; ++i) {
-            oldHandlers[i].call(server, req, res);
-        }
-    });
-
-    function handler(req, res, next) {
-        var path, read;
-        if (!check.test(req.url)) {
-            return false;
-        }
-        path = dist + req.url.replace(check, '');
-        console.log('checking static path: %s', path);
-        read = require('fs').createReadStream(path);
-        read.pipe(res);
-        read.on('error', function (e) {
-            console.log('Stream error: %s', e.message);
-        });
-
-        return true;
-    }
-
-    /*
-     * Connecting stream + websocket server
-     */
-    return require('./stream').attach(server);
-};

lib/stream.js

@@ -1,50 +0,0 @@
-/*jshint node:true*/
-/*
- * Sets up a real stream + attaches it to a server
- */
-module.exports.attach = function droneStream(server) {
-    'use strict';
-    var WebSocketServer = require('ws').Server,
-        wss = new WebSocketServer({server: server, path: '/dronestream'}),
-        sockets = [],
-        Parser = require('./PaVEParser'),
-        arDrone = require('ar-drone');
-
-    function init() {
-        var tcpVideoStream = new arDrone.Client.PngStream.TcpVideoStream({
-                timeout: 4000
-            }),
-            p = new Parser();
-
-        console.log("Connecting to stream");
-
-        tcpVideoStream.connect(function () {
-            tcpVideoStream.pipe(p);
-        });
-
-        tcpVideoStream.on('error', function (err) {
-            console.log('There was an error: %s', err.message);
-            tcpVideoStream.end();
-            tcpVideoStream.emit("end");
-            init();
-        });
-
-        p.on('data', function (data) {
-            sockets.forEach(function (socket) {
-                socket.send(data, {binary: true});
-            });
-        });
-    }
-    init();
-
-    wss.on('connection', function (socket) {
-        sockets.push(socket);
-
-        socket.on("close", function () {
-            console.log("Closing socket");
-            sockets = sockets.filter(function (el) {
-                return el !== socket;
-            });
-        });
-    });
-};

package.json

@@ -1,12 +1,11 @@
 {
   "name": "dronestream",
   "description": "video live stream from your parrot ar.drone 2.0 to your browser in pure javascript",
-  "version": "1.0.2",
+  "version": "0.2.0",
   "repository": {
     "type": "git",
     "url": "git@github.com:bkw/node-dronestream.git"
   },
-  "main": "index",
   "keywords": [
     "drone",
     "nodecopter",
@@ -16,17 +15,16 @@
     "browser",
     "x264"
   ],
+  "scripts": {
+    "start": "node app"
+  },
   "dependencies": {
+    "express": "3.0.0rc5",
+    "jade": "*",
     "ws": "~0.4.22",
-    "ar-drone": "0.0.5",
-    "buffy": "0.0.5"
+    "ar-drone": "0.0.3",
+    "buffy": "0.0.4"
   },
   "author": "Bernhard K. Weisshuhn <bkw@codingforce.com>",
-  "contributors": [
-    {
-      "name": "Karl Westin",
-      "email": "karl.westin@gmail.com"
-    }
-  ],
   "license": "BSD"
 }

public/js/nodecopter-stream.js

@@ -0,0 +1,84 @@
+/*jshint browser:true */
+/*global Avc:true, YUVWebGLCanvas: true, Size: true */
+(function (window, document, undefined) {
+    'use strict';
+    var NS,
+        socket,
+        avc,
+        webGLCanvas,
+        width,
+        height;
+
+    function setupAvc() {
+        avc = new Avc();
+        avc.configure({
+            filter: 'original',
+            filterHorLuma: 'optimized',
+            filterVerLumaEdge: 'optimized',
+            getBoundaryStrengthsA: 'optimized'
+        });
+        avc.onPictureDecoded = handleDecodedFrame;
+    }
+
+    function handleNalUnits(message) {
+        avc.decode(new Uint8Array(message.data));
+    }
+
+    function handleDecodedFrame(buffer, width, height) {
+        var lumaSize = width * height,
+            chromaSize = lumaSize >> 2;
+        webGLCanvas.YTexture.fill(buffer.subarray(0, lumaSize));
+        webGLCanvas.UTexture.fill(buffer.subarray(lumaSize, lumaSize + chromaSize));
+        webGLCanvas.VTexture.fill(buffer.subarray(lumaSize + chromaSize, lumaSize + 2 * chromaSize));
+        webGLCanvas.drawScene();
+    }
+
+    function setupCanvas(div) {
+        var canvas = document.createElement('canvas');
+
+        width = div.attributes.width ? div.attributes.width.value : 640;
+        height = div.attributes.height ? div.attributes.height.value : 360;
+
+        canvas.width = width;
+        canvas.height = height;
+        canvas.style.backgroundColor = "#333333";
+        div.appendChild(canvas);
+
+        webGLCanvas = new YUVWebGLCanvas(canvas, new Size(width, height));
+    }
+
+
+    NS = function (div) {
+        setupCanvas(div);
+        setupAvc();
+
+        socket = new WebSocket(
+             'ws://' +
+            window.document.location.hostname + ':' +
+            window.document.location.port
+        );
+        socket.binaryType = 'arraybuffer';
+        socket.onmessage = handleNalUnits;
+    };
+
+    NS.prototype.getImageData = function (rgbaData) {
+        var gl = webGLCanvas.gl;
+
+        gl.readPixels(
+            0, 0, width, height,
+            gl.RGBA, gl.UNSIGNED_BYTE,
+            rgbaData
+        );
+        // WebGL returns pixels upside down.
+        // Instead of wasting time by vertically flipping it now,
+        // we just leave it like it is and invert the coordinates later:
+        return;
+    };
+
+    NS.prototype.getCanvas = function () {
+        return webGLCanvas.canvas;
+    };
+
+    window.NodecopterStream = NS;
+
+}(window, document, undefined));

public/js/nodecopter-track.js

@@ -0,0 +1,156 @@
+/*jshint browser:true */
+/*global jsfeat:true console:true */
+(function (window, document, undefined) {
+    'use strict';
+    var NodecopterTrack,
+        lastTime;
+
+    function schedule (callback, element) {
+          var requestAnimationFrame =
+              window.requestAnimationFrame        ||
+              window.webkitRequestAnimationFrame  ||
+              window.mozRequestAnimationFrame     ||
+              window.oRequestAnimationFrame       ||
+              window.msRequestAnimationFrame      ||
+              function(callback, element) {
+                  var currTime = new Date().getTime(),
+                      timeToCall = Math.max(0, 16 - (currTime - lastTime)),
+                      id = window.setTimeout(function() {
+                            callback(currTime + timeToCall);
+                      }, timeToCall);
+                  lastTime = currTime + timeToCall;
+                  return id;
+              };
+
+          return requestAnimationFrame.call(window, callback, element);
+    }
+
+
+    var relMouseCoords = function (event) {
+        var totalOffsetX = 0,
+            totalOffsetY = 0,
+            canvasX = 0,
+            canvasY = 0,
+            currentElement = this;
+
+        do {
+            totalOffsetX += currentElement.offsetLeft - currentElement.scrollLeft;
+            totalOffsetY += currentElement.offsetTop - currentElement.scrollTop;
+        } while (currentElement = currentElement.offsetParent);
+
+        canvasX = event.pageX - totalOffsetX;
+        canvasY = event.pageY - totalOffsetY;
+        return {x:canvasX, y:canvasY};
+    };
+
+
+    NodecopterTrack = function (copterStream, imgId) {
+        var tracker = this;
+        this.curr_img_pyr = new jsfeat.pyramid_t(3);
+        this.prev_img_pyr = new jsfeat.pyramid_t(3);
+        this.point_count  = 0;
+        this.point_status = new Uint8Array(1);
+        this.prev_xy      = new Float32Array(2);
+        this.curr_xy      = new Float32Array(2);
+        this.copterStream = copterStream;
+        this.canvas       = copterStream.getCanvas();
+        this.rgbaData     = new Uint8Array(
+            this.canvas.width * this.canvas.height * 4
+        ); // RGBA
+        this.crosshairs   = document.querySelector(imgId);
+
+        this.curr_img_pyr.allocate(
+            this.canvas.width, this.canvas.height, jsfeat.U8_t | jsfeat.C1_t
+        );
+        this.prev_img_pyr.allocate(
+            this.canvas.width, this.canvas.height, jsfeat.U8_t | jsfeat.C1_t
+        );
+
+        this.canvas.addEventListener('click', function(event) {
+            tracker.canvasClickHandler(event);
+        }, false);
+        HTMLCanvasElement.prototype.relMouseCoords = relMouseCoords;
+        // this.canvas.prototype.relMouseCoords = relMouseCoords;
+
+        this.update();
+    };
+
+    NodecopterTrack.prototype.update = function () {
+        var _pt_xy, _pyr,
+            tracker = this;
+
+        schedule(function () {
+            tracker.update();
+        });
+
+        if (! this.point_count) {
+            this.crosshairs.style.display = 'none';
+            return;
+        }
+
+        _pt_xy = this.prev_xy;
+        _pyr = this.prev_img_pyr;
+
+        this.prev_xy = this.curr_xy;
+        this.curr_xy = _pt_xy;
+
+        this.prev_img_pyr = this.curr_img_pyr;
+        this.curr_img_pyr = _pyr; // reuse old pyramid data structure
+
+        this.copterStream.getImageData(this.rgbaData);
+        jsfeat.imgproc.grayscale(
+            this.rgbaData,
+            this.curr_img_pyr.data[0].data
+        );
+
+        // optional: enhance contrast:
+        jsfeat.imgproc.equalize_histogram(
+            this.curr_img_pyr.data[0].data,
+            this.curr_img_pyr.data[0].data
+        );
+
+        this.curr_img_pyr.build(this.curr_img_pyr.data[0], true);
+
+        jsfeat.optical_flow_lk.track(
+            this.prev_img_pyr,
+            this.curr_img_pyr,
+            this.prev_xy,
+            this.curr_xy,
+            1,
+            50,            // win_size
+            30,            // max_iterations
+            this.point_status,
+            0.01,          // epsilon,
+            0.001          // min_eigen
+        );
+
+        if (this.point_status[0] == 1) {
+            this.crosshairs.style.left = (this.curr_xy[0] - 83) + 'px';
+            this.crosshairs.style.top = (
+                this.canvas.height - 83 - this.curr_xy[1]
+            ) + 'px';
+            this.crosshairs.style.display = 'block';
+        } else {
+            this.point_count = 0;
+            console.log('lost target');
+        }
+    };
+
+    NodecopterTrack.prototype.canvasClickHandler = function (e) {
+        var coords = this.canvas.relMouseCoords(e);
+        if (
+            (coords.x > 0) &&
+            (coords.y > 0) &&
+            (coords.x < this.canvas.width) &&
+            (coords.y < this.canvas.height)
+        ) {
+            this.curr_xy[0] = coords.x;
+            this.curr_xy[1] = this.canvas.height - coords.y;
+            this.point_count = 1;
+        }
+        console.log('Click:', coords);
+    };
+
+    window.NodecopterTrack = NodecopterTrack;
+
+}(window, document, undefined));

public/js/vendor/broadway/canvas.js

@@ -337,7 +337,7 @@ var WebGLCanvas = (function () {
     },
     onInitWebGL: function () {
       try {
-        this.gl = this.canvas.getContext("experimental-webgl");
+        this.gl = this.canvas.getContext("experimental-webgl", {preserveDrawingBuffer: true});
       } catch(e) {}
       
       if (!this.gl) {

views/index.jade

@@ -0,0 +1,22 @@
+extends layout
+
+block append head
+  script(type='text/javascript', src='/js/vendor/broadway/sylvester.js')
+  script(type='text/javascript', src='/js/vendor/broadway/glUtils.js')
+  script(type='text/javascript', src='/js/vendor/broadway/util.js')
+  script(type='text/javascript', src='/js/vendor/broadway/avc-codec.js')
+  script(type='text/javascript', src='/js/vendor/broadway/avc.js')
+  script(type='text/javascript', src='/js/vendor/broadway/canvas.js')
+  script(type='text/javascript', src='/js/vendor/jsfeat/jsfeat-min.js')
+  script(type='text/javascript', src='/js/nodecopter-stream.js')
+  script(type='text/javascript', src='/js/nodecopter-track.js')
+
+block append bodyscripts
+  script
+    'use strict';
+    var copterStream = new NodecopterStream(document.querySelector('#dronestream'));
+    var tracker = new NodecopterTrack(copterStream, '#sniper');
+
+block content
+  div#dronestream(width=640, height=360, style="position:relative")
+    img#sniper(src="images/sniper.png", style="position:absolute; opacity:0.6")

views/layout.jade

@@ -7,6 +7,7 @@ html
       title= title
       link(rel='stylesheet', href='/css/normalize.min.css')
       link(rel='stylesheet', href='/css/style.css')
+      script(src='/js/vendor/h5bp/modernizr-2.6.1-respond-1.1.0.min.js')
   body
     div.header-container
       header.wrapper.clearfix