Added new callbacks for assets load tracking also to SceneLoader.

It works both for JSON models and textures. Handling of every asynchronously loaded asset triggers calls to "onLoadStart" and "onLoadComplete" callbacks.

src/extras/io/SceneLoader.js

@@ -3,12 +3,19 @@
  */
 
 THREE.SceneLoader = function () {
+
+	this.onLoadStart = function () {};
+	this.onLoadProgress = function() {};
+	this.onLoadComplete = function () {};
+
 };
 
 THREE.SceneLoader.prototype = {
 
 	load : function ( url, callback_sync, callback_async, callback_progress ) {
 
+		var scope = this;
+
 		var worker = new Worker( url );
 		worker.postMessage( 0 );
 
@@ -189,6 +196,8 @@ THREE.SceneLoader.prototype = {
 					handle_mesh( geo, id );
 
 					counter_models -= 1;
+					
+					scope.onLoadComplete();
 
 					async_callback_gate();
 
@@ -208,6 +217,8 @@ THREE.SceneLoader.prototype = {
 				};
 
 				callback_progress( progress, result );
+				
+				scope.onLoadProgress();
 
 				if( counter_models == 0 && counter_textures == 0 ) {
 
@@ -222,6 +233,8 @@ THREE.SceneLoader.prototype = {
 				counter_textures -= 1;
 				async_callback_gate();
 
+				scope.onLoadComplete();
+
 			};
 
 			// first go synchronous elements
@@ -342,6 +355,8 @@ THREE.SceneLoader.prototype = {
 				if ( g.type == "bin_mesh" || g.type == "ascii_mesh" ) {
 
 					counter_models += 1;
+					
+					scope.onLoadStart();
 
 				}
 
@@ -410,11 +425,19 @@ THREE.SceneLoader.prototype = {
 				if( tt.url instanceof Array ) {
 
 					counter_textures += tt.url.length;
+					
+					for( var n = 0; n < tt.url.length; n ++ ) {
+						
+						scope.onLoadStart();
+
+					}
 
 				} else {
 
 					counter_textures += 1;
 
+					scope.onLoadStart();
+
 				}
 
 			}