Actually pause singleplayer game in pause menu and use lower maximum FPS in it

minetest.conf.example

@@ -68,6 +68,8 @@
 # If FPS would go higher than this, limit it by sleeping
 # (to not waste CPU power for no benefit)
 #fps_max = 60
+# Maximum FPS when game is paused
+#pause_fps_max = 20
 # The allowed adjustment range for the automatic rendering range adjustment
 #viewing_range_nodes_max = 160
 #viewing_range_nodes_min = 35

src/defaultsettings.cpp

@@ -77,6 +77,7 @@ void set_default_settings(Settings *settings)
 
 	settings->setDefault("wanted_fps", "30");
 	settings->setDefault("fps_max", "60");
+	settings->setDefault("pause_fps_max", "20");
 	// A bit more than the server will send around the player, to make fog blend well
 	settings->setDefault("viewing_range_nodes_max", "240");
 	settings->setDefault("viewing_range_nodes_min", "35");

src/game.cpp

@@ -1513,7 +1513,9 @@ void the_game(
 		*/
 
 		{
-			float fps_max = g_settings->getFloat("fps_max");
+			float fps_max = g_menumgr.pausesGame() ?
+					g_settings->getFloat("pause_fps_max") :
+					g_settings->getFloat("fps_max");
 			u32 frametime_min = 1000./fps_max;
 			
 			if(busytime_u32 < frametime_min)
@@ -2194,23 +2196,26 @@ void the_game(
 		}
 
 		/*
-			Run server
+			Run server, client (and process environments)
 		*/
-
+		bool can_be_and_is_paused =
+				(simple_singleplayer_mode && g_menumgr.pausesGame());
+		if(can_be_and_is_paused)
+		{
+			// No time passes
+			dtime = 0;
+		}
+		else
+		{
 			if(server != NULL)
 			{
 				//TimeTaker timer("server->step(dtime)");
 				server->step(dtime);
 			}
-
-		/*
-			Process environment
-		*/
-		
 			{
 				//TimeTaker timer("client.step(dtime)");
 				client.step(dtime);
-			//client.step(dtime_avg1);
+			}
 		}
 
 		{

src/guiPauseMenu.h

@@ -52,6 +52,8 @@ public:
 
 	bool OnEvent(const SEvent& event);
 
+	bool pausesGame(){ return true; }
+
 private:
 	IGameCallback *m_gamecallback;
 	bool m_simple_singleplayer_mode;

src/guiVolumeChange.h

@@ -44,6 +44,8 @@ public:
 
 	bool OnEvent(const SEvent& event);
 	
+	bool pausesGame(){ return true; }
+
 private:
 	Client* m_client;
 

src/mainmenumanager.h

@@ -91,6 +91,17 @@ public:
 		return m_stack.size();
 	}
 
+	bool pausesGame()
+	{
+		for(std::list<GUIModalMenu*>::iterator
+				i = m_stack.begin(); i != m_stack.end(); ++i)
+		{
+			if((*i)->pausesGame())
+				return true;
+		}
+		return false;
+	}
+
 	std::list<GUIModalMenu*> m_stack;
 };
 

src/modalMenu.h

@@ -124,6 +124,7 @@ public:
 	virtual void drawMenu() = 0;
 	virtual bool preprocessEvent(const SEvent& event) { return false; };
 	virtual bool OnEvent(const SEvent& event) { return false; };
+	virtual bool pausesGame(){ return false; } // Used for pause menu
 
 protected:
 	//bool m_force_regenerate_gui;