Use CBOR compression for PointCloud2 (#239)

* Use CBOR encoding for PointCloud2

* Don't reassign PointCloud2 buffer

Reassigning the buffer breaks underlying parts.

* Selectable compression in PointCloud2

src/sensors/PointCloud2.js

@@ -48,6 +48,7 @@ for(var i=0;i<64;i++){decode64.e[decode64.S.charAt(i)]=i;}
  *  * ros - the ROSLIB.Ros connection handle
  *  * topic - the marker topic to listen to (default: '/points')
  *  * tfClient - the TF client handle to use
+ *  * compression (optional) - message compression (default: 'cbor')
  *  * rootObject (optional) - the root object to add this marker to use for the points.
  *  * max_pts (optional) - number of points to draw (default: 10000)
  *  * pointRatio (optional) - point subsampling ratio (default: 1, no subsampling)
@@ -60,6 +61,7 @@ ROS3D.PointCloud2 = function(options) {
   options = options || {};
   this.ros = options.ros;
   this.topicName = options.topic || '/points';
+  this.compression = options.compression || 'cbor';
   this.points = new ROS3D.Points(options);
   this.rosTopic = undefined;
   this.subscribe();
@@ -80,7 +82,8 @@ ROS3D.PointCloud2.prototype.subscribe = function(){
   this.rosTopic = new ROSLIB.Topic({
     ros : this.ros,
     name : this.topicName,
-    messageType : 'sensor_msgs/PointCloud2'
+    messageType : 'sensor_msgs/PointCloud2',
+    compression: this.compression
   });
   this.rosTopic.subscribe(this.processMessage.bind(this));
 };
@@ -93,7 +96,7 @@ ROS3D.PointCloud2.prototype.processMessage = function(msg){
   var n, pointRatio = this.points.pointRatio;
 
   if (msg.data.buffer) {
-    this.points.buffer = msg.data.buffer;
+    this.points.buffer.set(msg.data);
     n = msg.height*msg.width / pointRatio;
   } else {
     n = decode64(msg.data, this.points.buffer, msg.point_step, pointRatio);