Simple example for Node.js

examples/README.md

@@ -7,6 +7,8 @@ This directory contains sample projects and configuration files for Fadecandy.
   * Examples for [Processing 2](http://processing.org/), a popular tool for creative coding
 * `html`
   * Browser-based examples, written in JavaScript with HTML5
+* `node`
+  * JavaScript examples for Node.js
 * `python`
   * Some examples written in [Python](http://python.org/)
 * `config`

examples/node/README.md

+Fadecandy Node.js Examples
+==========================
+
+This directory contains examples for Fadecandy written in [Node.js](http://nodejs.org/).
+
+Stable Examples
+---------------
+
+* `strip_redblue`
+  * An example for LED strips. A fade of blue, white, and red washes across the LEDs.

examples/node/opc.js

+/*
+ * Simple Open Pixel Control client for Node.js
+ *
+ * 2013 Micah Elizabeth Scott
+ * This file is released into the public domain.
+ */
+
+var net = require('net');
+
+var OPC = function(host, port)
+{
+    this.host = host;
+    this.port = port;
+    this.pixelBuffer = null;
+};
+
+OPC.prototype._reconnect = function()
+{
+    var _this = this;
+
+    this.socket = new net.Socket()
+    this.connected = false;
+
+    this.socket.onclose = function() {
+        console.log("Connection closed");
+        _this.socket = null;
+        _this.connected = false;
+    }
+
+    this.socket.connect(this.port, this.host, function() {
+        console.log("Connected to " + _this.socket.remoteAddress);
+        _this.connected = true;
+        _this.socket.setNoDelay();
+    });
+}
+
+OPC.prototype.writePixels = function()
+{
+    if (!this.socket) {
+        this._reconnect();
+    }
+    if (!this.connected) {
+        return;
+    }
+    this.socket.write(this.pixelBuffer);
+}
+
+OPC.prototype.setPixelCount = function(num)
+{
+    var length = 4 + num*3;
+    if (this.pixelBuffer == null || this.pixelBuffer.length != length) {
+        this.pixelBuffer = new Buffer(length);
+    }
+
+    // Initialize OPC header
+    this.pixelBuffer.writeUInt8(0, 0);           // Channel
+    this.pixelBuffer.writeUInt8(0, 1);           // Command
+    this.pixelBuffer.writeUInt16BE(num * 3, 2);  // Length
+}
+
+OPC.prototype.setPixel = function(num, r, g, b)
+{
+    var offset = 4 + num*3;
+    if (this.pixelBuffer == null || offset + 3 > this.pixelBuffer.length) {
+        this.setPixelCount(num + 1);
+    }
+
+    this.pixelBuffer.writeUInt8(Math.max(0, Math.min(255, r | 0)), offset);
+    this.pixelBuffer.writeUInt8(Math.max(0, Math.min(255, g | 0)), offset + 1);
+    this.pixelBuffer.writeUInt8(Math.max(0, Math.min(255, b | 0)), offset + 2);
+}
+
+module.exports = OPC;

examples/node/strip_redblue.js

+// Simple red/blue fade with Node and opc.js
+
+var OPC = new require('./opc')
+var client = new OPC('localhost', 7890);
+
+var draw = function()
+{
+    var millis = new Date().getTime();
+
+    for (var pixel = 0; pixel < 512; pixel++)
+    {
+        var t = pixel * 0.2 + millis * 0.002;
+        var red = 128 + 96 * Math.sin(t);
+        var green = 128 + 96 * Math.sin(t + 0.1);
+        var blue = 128 + 96 * Math.sin(t + 0.3);
+
+        client.setPixel(pixel, red, green, blue);
+    }
+    client.writePixels();
+}
+
+setInterval(draw, 30);