Create a game settings tab in the settings view and add a difficulty …

data/lang/ui-core/en.json

@@ -355,6 +355,10 @@
     "description": "tooltip description in settings menu",
     "message": "Lower gives better performance, at cost of visual aesthetics"
   },
+  "DIFFICULTY": {
+    "description": "Label next to the slider that allows the player to set the difficulty of the game",
+    "message": "Difficulty"
+  },
   "DISABLE_SCREENSHOT_INFO": {
     "description": "",
     "message": "Disable Screenshot Info"
@@ -658,6 +662,10 @@
   "GAME_TIME": {
     "description": "",
     "message": "Game time"
+  },  
+  "GAMEPLAY": {
+    "description": "The tooltip for the settings/options tab for changing gameplay related options",
+    "message": "Gameplay"
   },
   "GENERAL_CREW": {
     "description": "",

data/meta/CoreObject/Game.meta.lua

@@ -14,8 +14,7 @@
 ---@field sectorView unknown #TODO: add type info for SectorView interface
 ---@field time number Game time in seconds since Jan. 1 3200
 ---@field paused boolean
-
----@class Game
+---@field difficulty number The current game difficulty (between 0 and 1, easy to hard).  See also Engine.SetDifficulty
 local Game = {}
 
 -- Ensure the CoreImport field is visible to static analysis

data/meta/Engine.lua

@@ -18,6 +18,15 @@
 ---@class Engine
 local Engine = {}
 
--- TODO: add information about Engine methods
+-- TODO: add information about all Engine methods
+
+--- Get the current difficulty - either that for the current loaded game or the default for any new game if there is no game loaded
+--- see also Game.difficulty
+---@return integer Difficulty from 0 to 100, easy to hard
+function Engine:GetDifficulty() end
+
+--- Set the difficulty for the current game (if loaded) and the default for any new games created
+---@param percent integer Difficulty from 1 to 100 (clamped)
+function Engine:SetDifficulty( percent ) end
 
 return Engine

data/pigui/modules/settings-window.lua

@@ -37,6 +37,8 @@ local needBackgroundStarRefresh = false
 local starDensity = Engine.GetAmountStars() * 100
 local starFieldStarSizeFactor = Engine.GetStarFieldStarSizeFactor() * 100
 
+local difficulty = Engine.GetDifficulty()
+
 local function combo(label, selected, items, tooltip)
 	local color = colors.buttonBlue
 	local changed, ret = 0, nil
@@ -170,7 +172,6 @@ local function showVideoOptions()
 	local displaySpeedLines = Engine.GetDisplaySpeedLines()
 	local displayHudTrails = Engine.GetDisplayHudTrails()
 	local enableCockpit = Engine.GetCockpitEnabled()
-	local enableAutoSave = Engine.GetAutosaveEnabled()
 
 	local c
 	ui.text(lui.VIDEO_CONFIGURATION_RESTART_GAME_TO_APPLY)
@@ -253,11 +254,6 @@ local function showVideoOptions()
 		Engine.SetCockpitEnabled(enableCockpit)
 	end
 
-	c,enableAutoSave = checkbox(lui.ENABLE_AUTOSAVE, enableAutoSave, lui.ENABLE_AUTOSAVE_DESC)
-	if c then
-		Engine.SetAutosaveEnabled(enableAutoSave)
-	end
-
 	c,starDensity = slider(lui.STAR_FIELD_DENSITY, starDensity, 0, 100)
 	if c then
 		needBackgroundStarRefresh = true
@@ -637,11 +633,25 @@ local function showControlsOptions()
 	end
 end
 
+local function showGameplayOptions()
+	local enableAutoSave = Engine.GetAutosaveEnabled()
+
+	local c
+
+	c,enableAutoSave = checkbox(lui.ENABLE_AUTOSAVE, enableAutoSave, lui.ENABLE_AUTOSAVE_DESC)
+	if c then
+		Engine.SetAutosaveEnabled(enableAutoSave)
+	end
+
+	c,difficulty = slider(lui.DIFFICULTY, difficulty, 0, 100)
+end
+
 local optionsTabs = {
 	["video"]=showVideoOptions,
 	["sound"]=showSoundOptions,
 	["language"]=showLanguageOptions,
-	["controls"]=showControlsOptions
+	["controls"]=showControlsOptions,
+	["gameplay"]=showGameplayOptions,
 }
 
 ui.optionsWindow = ModalWindow.New("Options", function()
@@ -660,6 +670,11 @@ ui.optionsWindow = ModalWindow.New("Options", function()
 	mainButton(icons.controls, lui.CONTROLS, showTab=='controls', function()
 		showTab = 'controls'
 	end)
+	ui.sameLine()
+	-- TODO: localize
+	mainButton(icons.star, lui.GAMEPLAY, showTab=='gameplay', function()
+		showTab = 'gameplay'
+	end)
 
 	ui.separator()
 
@@ -690,6 +705,7 @@ ui.optionsWindow = ModalWindow.New("Options", function()
 	if Game.player then
 		ui.sameLine()
 		optionTextButton(lui.SAVE, nil, Game.player.flightState ~= 'HYPERSPACE', function()
+			ui.optionsWindow:persist()
 			ui.saveLoadWindow.mode = "SAVE"
 			ui.saveLoadWindow:open()
 		end)
@@ -716,17 +732,25 @@ end
 
 function ui.optionsWindow:open()
 	ModalWindow.open(self)
+	difficulty = Engine.GetDifficulty()
 	if Game.player then
 		Input.EnableBindings(false)
 		Event.Queue("onPauseMenuOpen")
 	end
 end
 
+function ui.optionsWindow:persist()
+	Engine.SetDifficulty( difficulty )
+	if Game.player then
+		Game.SetTimeAcceleration("1x")
+	end
+end
+
 function ui.optionsWindow:close()
+	self:persist()
 	if not captureBindingWindow.isOpen then
 		ModalWindow.close(self)
 		if Game.player then
-			Game.SetTimeAcceleration("1x")
 			Event.Queue("onPauseMenuClosed")
 		end
 	end

src/Game.cpp

@@ -4,6 +4,7 @@
 #include "buildopts.h"
 
 #include "Game.h"
+#include "GameConfig.h"
 
 #include "Body.h"
 #include "DeathView.h"
@@ -48,6 +49,10 @@ Game::Game(const SystemPath &path, const double startDateTime, const char *shipT
 	m_forceTimeAccel(false)
 {
 	PROFILE_SCOPED()
+
+	int difficulty = Pi::config->Int("Difficulty", 50);
+	m_difficulty = difficulty / 100.0;
+
 	// Now that we have a Galaxy, check the starting location
 	if (!path.IsBodyPath())
 		throw InvalidGameStartLocation("SystemPath is not a body path");
@@ -171,6 +176,17 @@ Game::Game(const Json &jsonObj) :
 		m_hyperspaceDuration = jsonObj["hyperspace_duration"];
 		m_hyperspaceEndTime = jsonObj["hyperspace_end_time"];
 
+//		Our version is too old for this (at least on windows)...
+// 		if (jsonObj.contains("difficulty"))
+		if (jsonObj.cend() != jsonObj.find("difficulty"))
+		{
+			m_difficulty = jsonObj["difficulty"];
+		} else
+		{
+			int difficulty = Pi::config->Int("Difficulty", 50);
+			m_difficulty = difficulty / 100.0;
+		}
+
 		// space, all the bodies and things
 		m_space.reset(new Space(this, m_galaxy, jsonObj, m_time));
 
@@ -228,6 +244,8 @@ void Game::ToJson(Json &jsonObj)
 	jsonObj["hyperspace_duration"] = m_hyperspaceDuration;
 	jsonObj["hyperspace_end_time"] = m_hyperspaceEndTime;
 
+	jsonObj["difficulty"] = m_difficulty;
+
 	// Delete camera frame from frame structure:
 	bool have_cam_frame = m_gameViews->m_worldView->GetCameraContext()->GetTempFrame().valid();
 	if (have_cam_frame) m_gameViews->m_worldView->EndCameraFrame();
@@ -759,6 +777,14 @@ ObjectViewerView *Game::GetObjectViewerView() const
 }
 #endif
 
+void Game::SetDifficulty(double difficulty)
+{
+	difficulty = std::max(difficulty, 0.0);
+	difficulty = std::min(difficulty, 1.0);
+	m_difficulty = difficulty;
+}
+
+
 Game::Views::Views() :
 	m_sectorView(nullptr),
 	m_systemView(nullptr),

src/Game.h

@@ -125,6 +125,12 @@ class Game {
 
 	GameLog *log;
 
+	// for debug purposes only
+	unsigned int GetFrameNumber() const { return m_frameNumber; }
+
+	double GetDifficulty() const { return m_difficulty; }
+	void SetDifficulty(double difficulty);
+
 private:
 	class Views {
 	public:
@@ -182,6 +188,10 @@ class Game {
 	bool m_forceTimeAccel;
 	static const float s_timeAccelRates[];
 	static const float s_timeInvAccelRates[];
+
+	double m_difficulty;
+
+	unsigned int m_frameNumber = 0;
 };
 
 #endif

src/lua/LuaEngine.cpp

@@ -1035,6 +1035,43 @@ static int l_browse_user_folders(lua_State *l)
 	return 0;
 }
 
+
+static int l_engine_set_difficulty(lua_State* l)
+{
+	int difficulty = LuaPull<int>(l, 1);
+	difficulty = std::max(0, difficulty);
+	difficulty = std::min(100, difficulty);
+	if (Pi::game)
+	{
+		Pi::game->SetDifficulty(difficulty/100.0);
+	}
+	int old_difficulty = Pi::config->Int("Difficulty", 50);
+	if (old_difficulty != difficulty)
+	{
+		Pi::config->SetInt("Difficulty", difficulty);
+		Pi::config->Save();
+	}
+
+	return 0;
+}
+
+// Return the difficulty of the current game, if there is one, else the saved, configured difficulty
+static int l_engine_get_difficulty(lua_State* l)
+{
+	int difficulty;
+	if (Pi::game)
+	{
+		// add 0.5 to ensure rounding
+		difficulty = (int)(Pi::game->GetDifficulty()*100.0 + 0.5);
+	}
+	else
+	{
+		difficulty = Pi::config->Int("Difficulty", 50);
+	}
+	LuaPush(l, difficulty);
+	return 1;
+}
+
 void LuaEngine::Register()
 {
 	lua_State *l = Lua::manager->GetLuaState();
@@ -1126,6 +1163,9 @@ void LuaEngine::Register()
 		{ "GetEnumValue", l_engine_get_enum_value },
 
 		{ "RequestProfileFrame", l_engine_request_profile_frame },
+		{ "SetDifficulty", l_engine_set_difficulty },
+		{ "GetDifficulty", l_engine_get_difficulty },
+
 		{ 0, 0 }
 	};
 

src/lua/LuaGame.cpp

@@ -420,6 +420,15 @@ static int l_game_attr_paused(lua_State *l)
 	return 1;
 }
 
+static int l_game_attr_difficulty(lua_State* l)
+{
+	if (Pi::game)
+		lua_pushnumber(l, Pi::game->GetDifficulty());
+	else
+		lua_pushnumber(l, 0.5);
+	return 1;
+}
+
 /*
  * Function: InHyperspace
  *
@@ -678,6 +687,7 @@ void LuaGame::Register()
 		{ "sectorView", l_game_attr_sectorview },
 		{ "time", l_game_attr_time },
 		{ "paused", l_game_attr_paused },
+		{ "difficulty", l_game_attr_difficulty },
 		{ 0, 0 }
 	};