move render thread to App class and add ui thread with ui tasks queue

src/app.h

@@ -73,7 +73,7 @@ public:
     std::mutex rec_mutex;
     std::condition_variable rec_cv;
     std::deque<std::unique_ptr<uint8_t[]>> rec_frames;
-    
+
     RTT uirtt;
     Sampler sampler;
     Sampler sampler_stencil;
@@ -251,11 +251,23 @@ public:
 
     void cmd_convert(std::string pano_path, std::string out_path);
 
+    //////////////////////////////////////////////////////////////////////////
+    // RENDER THREAD
+    //////////////////////////////////////////////////////////////////////////
+
+    std::deque<std::packaged_task<void()>> render_tasklist;
+    std::mutex render_task_mutex;
+    std::condition_variable render_cv;
+    std::thread render_thread;
+    std::thread::id render_thread_id;
+    bool render_running = false;
+    void render_thread_main();
+    void render_thread_start();
+    void render_thread_stop();
+
     bool is_render_thread()
     {
-        extern std::thread::id render_thread_id;
-        extern std::thread::id gl_thread;
-        return std::this_thread::get_id() == render_thread_id || std::this_thread::get_id() == gl_thread;
+        return std::this_thread::get_id() == render_thread_id;
     }
 
     // don't capture a reference to this ptr as the object may be destroyed
@@ -264,9 +276,6 @@ public:
     std::future<R> render_task_async(T task)
     {
 #ifdef _WIN32
-        extern std::deque<std::packaged_task<R()>> render_tasklist;
-        extern std::mutex render_task_mutex;
-        extern std::condition_variable render_cv;
         std::packaged_task<R()> pt(task);
         std::future<R> f = pt.get_future();
         if (is_render_thread())
@@ -289,9 +298,6 @@ public:
     R render_task(T task)
     {
 #ifdef _WIN32
-        extern std::deque<std::packaged_task<R()>> render_tasklist;
-        extern std::mutex render_task_mutex;
-        extern std::condition_variable render_cv;
         std::packaged_task<R()> pt(task);
         std::future<R> f = pt.get_future();
         if (is_render_thread())
@@ -306,7 +312,7 @@ public:
             }
             render_cv.notify_all();
         }
-        return f.get();
+        return render_running ? f.get() : R();
 #endif // _WIN32
     }
 
@@ -315,4 +321,73 @@ public:
         render_task([] {});
     }
 
+    //////////////////////////////////////////////////////////////////////////
+    // UI THREAD
+    //////////////////////////////////////////////////////////////////////////
+
+    std::deque<std::packaged_task<void()>> ui_tasklist;
+    std::mutex ui_task_mutex;
+    std::condition_variable ui_cv;
+    std::thread ui_thread;
+    std::thread::id ui_thread_id;
+    bool ui_running = false;
+    void ui_thread_main();
+    void ui_thread_start();
+    void ui_thread_stop();
+
+    bool is_ui_thread()
+    {
+        return std::this_thread::get_id() == ui_thread_id;
+    }
+
+    // don't capture a reference to this ptr as the object may be destroyed
+    // by the time the task is executed
+    template<typename T, typename R = std::result_of<T()>::type>
+    std::future<R> ui_task_async(T task)
+    {
+#ifdef _WIN32
+        std::packaged_task<R()> pt(task);
+        std::future<R> f = pt.get_future();
+        if (is_ui_thread())
+        {
+            pt();
+        }
+        else
+        {
+            {
+                std::lock_guard<std::mutex> lock(ui_task_mutex);
+                ui_tasklist.push_back(std::move(pt));
+            }
+            ui_cv.notify_all();
+        }
+        return f;
+#endif // _WIN32
+    }
+
+    template<typename T, typename R = std::result_of<T()>::type>
+    R ui_task(T task)
+    {
+#ifdef _WIN32
+        std::packaged_task<R()> pt(task);
+        std::future<R> f = pt.get_future();
+        if (is_ui_thread())
+        {
+            pt();
+        }
+        else
+        {
+            {
+                std::lock_guard<std::mutex> lock(ui_task_mutex);
+                ui_tasklist.push_back(std::move(pt));
+            }
+            ui_cv.notify_all();
+        }
+        return ui_running ? f.get() : R();
+#endif // _WIN32
+    }
+
+    void ui_sync()
+    {
+        ui_task([] {});
+    }
 };