add mutex to App::update, move custom app-glue to git submodule

src/app.cpp

@@ -443,7 +443,11 @@ void App::async_end()
 
 void App::update(float dt)
 {
+    static std::mutex mutex;
     static float rec_timer = 0.f;
+
+    // avoid multiple threads to update the scene
+    std::lock_guard<std::mutex> lock(mutex);
     
     static std::mutex m;
     std::lock_guard<std::mutex> _lock(m);
@@ -511,16 +515,19 @@ void App::update(float dt)
         }
         return false;
     };
-    /*
-    uirtt.bindFramebuffer();
-    uirtt.clear();
-    glEnable(GL_SCISSOR_TEST);
-    for (int i = 1; i < layout[main_id]->m_children.size(); i++)
-        layout[main_id]->m_children[i]->watch(observer);
-    //msgbox->watch(observer);
-    glDisable(GL_SCISSOR_TEST);
-    uirtt.unbindFramebuffer();
-    */
+    
+    if (vr_active)
+    {
+        uirtt.bindFramebuffer();
+        uirtt.clear();
+        glEnable(GL_SCISSOR_TEST);
+        for (int i = 1; i < layout[main_id]->m_children.size(); i++)
+            layout[main_id]->m_children[i]->watch(observer);
+        //msgbox->watch(observer);
+        glDisable(GL_SCISSOR_TEST);
+        uirtt.unbindFramebuffer();
+    }
+    
 #if __IOS__
     [ios_view->glview bindDrawable];
 #else