Fixed date and time consistency across Campaigns and Missions

This fixes campaign mission generation mostly, but a full playthrough
will be needed. Missions now serialize and accept stardate setting a
bit better. Thanks to this, date is propagated over multiplayer, too.

This seems to break points system?

Code-wise, this does not workaround the problems from before namely
over-reliance on side-effects. Stardate class is at least one small
step into good direction. Now, it'd be nice to attach clocks to
simulation and campaign and whatever else that needs them.

23 files changed, 441 insertions, 266 deletions

diff --git a/StarsEx/CMakeLists.txt b/StarsEx/CMakeLists.txt
index 4541191..6a6b4d6 100644
--- a/StarsEx/CMakeLists.txt
+++ b/StarsEx/CMakeLists.txt
@@ -39,18 +39,18 @@ add_library(
 	CmpCompleteDlg.cpp
 	CmpFileDlg.cpp
 	CmpLoadDlg.cpp
+	CmpnScreen.cpp
 	CmpSceneDlg.cpp
 	CmpSelectDlg.cpp
-	CmpnScreen.cpp
 	Color.cpp
 	CombatAction.cpp
+	Combatant.cpp
 	CombatAssignment.cpp
 	CombatEvent.cpp
 	CombatGroup.cpp
 	CombatRoster.cpp
 	CombatUnit.cpp
 	CombatZone.cpp
-	Combatant.cpp
 	ComboBox.cpp
 	ComboList.cpp
 	Component.cpp
@@ -74,7 +74,6 @@ add_library(
 	Element.cpp
 	Encrypt.cpp
 	EngDlg.cpp
-	UIEventDispatch.cpp
 	ExceptionHandler.cpp
 	ExitDlg.cpp
 	Explosion.cpp
@@ -89,9 +88,9 @@ add_library(
 	FltDlg.cpp
 	Font.cpp
 	FontMgr.cpp
+	FormatUtil.cpp
 	FormDef.cpp
 	FormWindow.cpp
-	FormatUtil.cpp
 	Galaxy.cpp
 	Game.cpp
 	GameScreen.cpp
@@ -100,20 +99,20 @@ add_library(
 	Graphic.cpp
 	Grid.cpp
 	GroundAI.cpp
-	HUDSounds.cpp
-	HUDView.cpp
 	Hangar.cpp
 	HardPoint.cpp
 	Hoop.cpp
+	HUDSounds.cpp
+	HUDView.cpp
 	ImageBox.cpp
 	ImgView.cpp
 	Instruction.cpp
 	Intel.cpp
 	JoyDlg.cpp
 	Joystick.cpp
+	Keyboard.cpp
 	KeyDlg.cpp
 	KeyMap.cpp
-	Keyboard.cpp
 	LandingGear.cpp
 	Layout.cpp
 	Light.cpp
@@ -121,8 +120,8 @@ add_library(
 	LoadDlg.cpp
 	LoadScreen.cpp
 	Locale_ss.cpp
-	MCIWave.cpp
 	MapView.cpp
+	MCIWave.cpp
 	Menu.cpp
 	MenuDlg.cpp
 	MenuScreen.cpp
@@ -135,8 +134,8 @@ add_library(
 	ModDlg.cpp
 	ModInfo.cpp
 	ModInfoDlg.cpp
-	Mouse.cpp
 	MouseController.cpp
+	Mouse.cpp
 	MsnDlg.cpp
 	MsnEditDlg.cpp
 	MsnEditNavDlg.cpp
@@ -150,7 +149,6 @@ add_library(
 	MultiController.cpp
 	MusicDirector.cpp
 	MusicTrack.cpp
-	NPClientWraps.cpp
 	NavAI.cpp
 	NavDlg.cpp
 	NavLight.cpp
@@ -162,11 +160,11 @@ add_library(
 	NetClientConfig.cpp
 	NetClientDlg.cpp
 	NetData.cpp
-	NetGame.cpp
 	NetGameClient.cpp
+	NetGame.cpp
 	NetGameServer.cpp
-	NetLobby.cpp
 	NetLobbyClient.cpp
+	NetLobby.cpp
 	NetLobbyDlg.cpp
 	NetLobbyServer.cpp
 	NetPacket.cpp
@@ -177,11 +175,12 @@ add_library(
 	NetUnitDlg.cpp
 	NetUser.cpp
 	NetUtil.cpp
+	NPClientWraps.cpp
 	OptDlg.cpp
-	Pcx.cpp
 	Panic.cpp
 	ParseUtil.cpp
 	Particles.cpp
+	Pcx.cpp
 	Physical.cpp
 	PlanScreen.cpp
 	Player.cpp
@@ -194,7 +193,6 @@ add_library(
 	QuantumFlash.cpp
 	QuantumView.cpp
 	QuitView.cpp
-	RLoc.cpp
 	RadioHandler.cpp
 	RadioMessage.cpp
 	RadioTraffic.cpp
@@ -203,6 +201,7 @@ add_library(
 	Random.cpp
 	Res.cpp
 	RichTextBox.cpp
+	RLoc.cpp
 	Scene.cpp
 	Screen.cpp
 	ScrollWindow.cpp
@@ -211,8 +210,8 @@ add_library(
 	Shadow.cpp
 	Shield.cpp
 	ShieldRep.cpp
-	Ship.cpp
 	ShipAI.cpp
+	Ship.cpp
 	ShipCtrl.cpp
 	ShipDesign.cpp
 	ShipKiller.cpp
@@ -225,23 +224,24 @@ add_library(
 	Sky.cpp
 	Slider.cpp
 	Solid.cpp
-	Sound.cpp
 	SoundCard.cpp
+	Sound.cpp
 	SoundD3D.cpp
 	Sprite.cpp
-	StarSystem.cpp
+	Stardate.cpp
 	Starshatter.cpp
 	StarshipAI.cpp
 	StarshipTacticalAI.cpp
+	StarSystem.cpp
 	SteerAI.cpp
 	System.cpp
 	SystemDesign.cpp
 	TacRefDlg.cpp
 	TacticalAI.cpp
 	TacticalView.cpp
-	Terrain.cpp
 	TerrainApron.cpp
 	TerrainClouds.cpp
+	Terrain.cpp
 	TerrainHaze.cpp
 	TerrainPatch.cpp
 	TerrainRegion.cpp
@@ -250,6 +250,7 @@ add_library(
 	Thruster.cpp
 	TrackIR.cpp
 	Trail.cpp
+	UIEventDispatch.cpp
 	VidDlg.cpp
 	Video.cpp
 	VideoDX9.cpp
@@ -331,6 +332,7 @@ endif()
 add_executable(
 	${PROJECT_NAME}_test
 	test/AudioConfig.cpp
+	test/Stardate.cpp
 	)
 generate_emulator(${PROJECT_NAME}_test LIBS Opcode ArchiveEx)
 target_link_libraries(${PROJECT_NAME}_test PRIVATE ${PROJECT_NAME} GTest::gtest_main)
diff --git a/StarsEx/Campaign.cpp b/StarsEx/Campaign.cpp
index 70846f0..b139787 100644
--- a/StarsEx/Campaign.cpp
+++ b/StarsEx/Campaign.cpp
@@ -12,33 +12,34 @@
 */
 
 #include "Campaign.h"
-#include "CampaignPlanStrategic.h"
+
+#include "Bitmap.h"
 #include "CampaignPlanAssignment.h"
 #include "CampaignPlanEvent.h"
 #include "CampaignPlanMission.h"
 #include "CampaignPlanMovement.h"
-#include "CampaignSituationReport.h"
+#include "CampaignPlanStrategic.h"
 #include "CampaignSaveGame.h"
-#include "Combatant.h"
+#include "CampaignSituationReport.h"
+#include "Clock.h"
 #include "CombatAction.h"
+#include "Combatant.h"
 #include "CombatEvent.h"
 #include "CombatGroup.h"
 #include "CombatRoster.h"
 #include "CombatUnit.h"
 #include "CombatZone.h"
-#include "Galaxy.h"
-#include "Mission.h"
-#include "StarSystem.h"
-#include "Starshatter.h"
-#include "Player.h"
-
 #include "ContentBundle.h"
-#include "Bitmap.h"
-#include "Clock.h"
 #include "DataLoader.h"
+#include "FormatUtil.h"
+#include "Galaxy.h"
+#include "Mission.h"
 #include "ParseUtil.h"
+#include "Player.h"
 #include "Random.h"
-#include "FormatUtil.h"
+#include "Stardate.h"
+#include "Starshatter.h"
+#include "StarSystem.h"
 
 
 const int TIME_NEVER = (int) 1e9;
@@ -108,7 +109,7 @@ static Campaign*        current_campaign = 0;
 
 Campaign::Campaign(int id, const char* n)
     : campaign_id(id), name(n), mission_id(-1), mission(0), net_mission(0),
-      scripted(false), sequential(false), time(0), startTime(0), loadTime(0),
+      scripted(false), sequential(false), time(0), load_time(0),
       player_group(0), player_unit(0), status(CAMPAIGN_INIT), lockout(0),
       loaded_from_savegame(false)
 {
@@ -118,7 +119,7 @@ Campaign::Campaign(int id, const char* n)
 
 Campaign::Campaign(int id, const char* n, const char* p)
     : campaign_id(id), name(n), mission_id(-1), mission(0), net_mission(0),
-      scripted(false), sequential(false), time(0), startTime(0), loadTime(0),
+      scripted(false), sequential(false), time(0), load_time(0),
       player_group(0), player_unit(0), status(CAMPAIGN_INIT), lockout(0),
       loaded_from_savegame(false)
 {
@@ -316,8 +317,6 @@ Campaign::Clear()
 
     player_group = 0;
     player_unit  = 0;
-
-    updateTime = time;
 }
 
 // +--------------------------------------------------------------------+
@@ -408,11 +407,10 @@ Campaign::Unload()
 {
     SetStatus(CAMPAIGN_INIT);
 
+    starshatter::engine::SetOperationStart();
+    starshatter::engine::SetMissionStart();
     Clock::GetInstance()->ResetGameTime();
-    StarSystem::SetBaseTime(0);
 
-    startTime = Stardate();
-    loadTime  = startTime;
     lockout   = 0;
 
     for (int i = 0; i < NUM_IMAGES; i++)
@@ -1849,7 +1847,7 @@ Campaign::SetMissionId(int id)
 long double
 Campaign::Stardate()
 {
-    return StarSystem::Stardate();
+    return starshatter::engine::OperationTime();
 }
 
 // +--------------------------------------------------------------------+
@@ -1882,7 +1880,9 @@ Campaign::Prep()
         LoadCampaign(loader, true);
     }
 
-    StarSystem::SetBaseTime(loadTime);
+    starshatter::engine::SetOperationStart();
+    starshatter::engine::SetMissionStart();
+    Clock::GetInstance()->ResetGameTime(load_time);
 
     // load scripted missions:
     if (IsScripted() && actions.isEmpty()) {
@@ -1917,7 +1917,7 @@ Campaign::ExecFrame()
     if (InCutscene())
     return;
 
-    time = Stardate() - startTime;
+    time = Stardate();
 
     if (status < CAMPAIGN_ACTIVE)
     return;
@@ -1936,12 +1936,10 @@ Campaign::ExecFrame()
             ::Print("Campaign::ExecFrame() destroying mission list after completion...\n");
             missions.destroy();
 
-            if (!player_group || player_group->IsFighterGroup())
-            time += 10 * 3600;
-            else
-            time += 20 * 3600;
-
-            StarSystem::SetBaseTime(startTime + time - Clock::GetInstance()->GameTime()/1000.0);
+            const auto factor = (!player_group || player_group->IsFighterGroup()) ? 10.0 : 20.0;
+            Clock::GetInstance()->ResetGameTime(starshatter::engine::OperationTime() + 3600.0 * factor);
+            starshatter::engine::SetMissionStart();
+            time = Stardate();
         }
         else {
             m.reset();
@@ -2043,20 +2041,10 @@ Campaign::StartMission()
         ::Print("\n\nCampaign Start Mission - %d. '%s'\n", m->Identity(), m->Name());
 
         if (!scripted) {
-            long double gtime = (long double) Clock::GetInstance()->GameTime() / 1000.0;
-            long double base  = startTime + m->Start() - 15 - gtime;
-
-            StarSystem::SetBaseTime(base);
-
-            long double current_time = Stardate() - startTime;
-
-            char buffer[32];
-            FormatDayTime(buffer, current_time);
-            ::Print("  current time:  %s\n", buffer);
-
-            FormatDayTime(buffer, m->Start());
-            ::Print("  mission start: %s\n", buffer);
-            ::Print("\n");
+            const auto now = starshatter::engine::OperationTime().Format();
+            const auto mission_start = starshatter::engine::Stardate{m->Start()}.Format();
+            ::Print("  current time:   %s\n", now.data());
+            ::Print("  mission start:  %s\n", mission_start.data());
         }
     }
 }
@@ -2070,14 +2058,10 @@ Campaign::RollbackMission()
 
     if (m) {
         if (!scripted) {
-            long double gtime = (long double) Clock::GetInstance()->GameTime() / 1000.0;
-            long double base  = startTime + m->Start() - 60 - gtime;
-
-            StarSystem::SetBaseTime(base);
-
-            long double current_time = Stardate() - startTime;
-            ::Print("  mission start: %d\n", m->Start());
-            ::Print("  current time:  %d\n", (int) current_time);
+            const auto now = starshatter::engine::OperationTime().Format();
+            const auto mission_start = starshatter::engine::Stardate{m->Start()}.Format();
+            ::Print("  current time:   %s\n", now.data());
+            ::Print("  mission start:  %s\n", mission_start.data());
         }
 
         m->SetActive(false);
@@ -2085,6 +2069,20 @@ Campaign::RollbackMission()
     }
 }
 
+
+long double
+Campaign::LoadTime() const
+{
+    return load_time;
+}
+
+
+void
+Campaign::SetLoadTime(long double value)
+{
+    load_time = value;
+}
+
 // +--------------------------------------------------------------------+
 
 bool
@@ -2229,22 +2227,6 @@ Campaign::FindStrikeTarget(int iff, CombatGroup* strike_group)
 
 // +--------------------------------------------------------------------+
 
-void
-Campaign::CommitExpiredActions()
-{
-    ListIter<CombatAction> iter = actions;
-    while (++iter) {
-        CombatAction* a = iter.value();
-
-        if (a->IsAvailable())
-        a->SetStatus(CombatAction::COMPLETE);
-    }
-
-    updateTime = time;
-}
-
-// +--------------------------------------------------------------------+
-
 int
 Campaign::GetPlayerTeamScore()
 {
diff --git a/StarsEx/Campaign.h b/StarsEx/Campaign.h
index c9bc534..8b38c51 100644
--- a/StarsEx/Campaign.h
+++ b/StarsEx/Campaign.h
@@ -130,7 +130,6 @@ public:
     virtual void         Unload();
 
     virtual void         Clear();
-    virtual void         CommitExpiredActions();
     virtual void         LockoutEvents(int seconds);
     virtual void         CheckPlayerGroup();
     void                 CreatePlanners();
@@ -190,12 +189,8 @@ public:
     int                  GetMissionId()    const { return mission_id;  }
     Bitmap*              GetImage(int n)         { return &image[n];   }
     long double          GetTime()         const { return time;        }
-    long double          GetStartTime()    const { return startTime;   }
-    void                 SetStartTime(long double t)  { startTime = t;      }
-    long double          GetLoadTime()     const      { return loadTime;    }
-    void                 SetLoadTime(long double t)   { loadTime = t;       }
-    long double          GetUpdateTime()   const      { return updateTime;  }
-    void                 SetUpdateTime(long double t) { updateTime = t;     }
+    long double          LoadTime()        const;
+    void                 SetLoadTime(long double value);
 
     bool                 InCutscene()      const;
     bool                 IsDynamic()       const;
@@ -272,9 +267,7 @@ protected:
     Mission*             net_mission;
 
     long double          time;
-    long double          loadTime;
-    long double          startTime;
-    long double          updateTime;
+    long double          load_time;
     int                  lockout;
 };
 
diff --git a/StarsEx/CampaignSaveGame.cpp b/StarsEx/CampaignSaveGame.cpp
index b959f01..62f8438 100644
--- a/StarsEx/CampaignSaveGame.cpp
+++ b/StarsEx/CampaignSaveGame.cpp
@@ -13,22 +13,24 @@
 */
 
 #include "CampaignSaveGame.h"
+
 #include "Campaign.h"
-#include "Combatant.h"
+#include "Clock.h"
 #include "CombatAction.h"
+#include "Combatant.h"
 #include "CombatEvent.h"
 #include "CombatGroup.h"
 #include "CombatUnit.h"
 #include "CombatZone.h"
+#include "DataLoader.h"
+#include "FormatUtil.h"
 #include "Galaxy.h"
-#include "Mission.h"
-#include "StarSystem.h"
-#include "Player.h"
-
 #include "Game.h"
-#include "DataLoader.h"
+#include "Mission.h"
 #include "ParseUtil.h"
-#include "FormatUtil.h"
+#include "Player.h"
+#include "Stardate.h"
+#include "StarSystem.h"
 
 static const char* SAVE_DIR = "SaveGame";
 
@@ -190,8 +192,8 @@ CampaignSaveGame::Load(const char* filename)
     int    grp_type = 0;
     int    grp_id   = 0;
     int    status   = 0;
-    double baseTime = 0;
-    double time     = 0;
+    long double baseTime = 0;
+    long double time     = 0;
     Text   unit;
     Text   sitrep;
     Text   orders;
@@ -470,8 +472,7 @@ CampaignSaveGame::Load(const char* filename)
             campaign->SetStatus(status);
             if (sitrep.length()) campaign->SetSituation(sitrep);
             if (orders.length()) campaign->SetOrders(orders);
-            campaign->SetStartTime(baseTime);
-            campaign->SetLoadTime(baseTime + time);
+            campaign->SetLoadTime(time);
             campaign->LockoutEvents(3600);
             campaign->Start();
 
@@ -567,9 +568,6 @@ CampaignSaveGame::Save(const char* name)
     fopen_s(&f, s, "wb");
 
     if (f) {
-        char timestr[32];
-        FormatDayTime(timestr, campaign->GetTime());
-
         CombatGroup* player_group = campaign->GetPlayerGroup();
         CombatUnit*  player_unit  = campaign->GetPlayerUnit();
 
@@ -582,10 +580,10 @@ CampaignSaveGame::Save(const char* name)
         fprintf(f, "unit:     \"%s\"\n", player_unit->Name().data());
 
         fprintf(f, "status:   %d\n",        (int) campaign->GetStatus());
-        fprintf(f, "basetime: %Lf\n",       campaign->GetStartTime());
-        fprintf(f, "time:     %Lf // %s\n\n",
-        campaign->GetTime(),
-        timestr);
+        fprintf(f, "basetime: %.1Lf\n", starshatter::engine::OperationStart());
+        const auto operation_time = starshatter::engine::OperationTime();
+        const auto formatted_time = operation_time.Format();
+        fprintf(f, "time:     %.1Lf  // %s\n\n", operation_time.value, formatted_time.data());
 
         fprintf(f, "sitrep:   \"%s\"\n",    campaign->Situation());
         fprintf(f, "orders:   \"%s\"\n\n",  campaign->Orders());
diff --git a/StarsEx/Clock.cpp b/StarsEx/Clock.cpp
index 60e6f67..252cc69 100644
--- a/StarsEx/Clock.cpp
+++ b/StarsEx/Clock.cpp
@@ -80,9 +80,10 @@ Clock::Step()
 
 
 void
-Clock::ResetGameTime()
+Clock::ResetGameTime(double seconds)
 {
-    m_game_elapsed = inner_clock::duration::zero();
+    const std::chrono::duration<double> target {seconds};
+    m_game_elapsed = std::chrono::duration_cast<inner_clock::duration>(target);
 }
 
 
diff --git a/StarsEx/Clock.h b/StarsEx/Clock.h
index 40b5262..08e5005 100644
--- a/StarsEx/Clock.h
+++ b/StarsEx/Clock.h
@@ -22,7 +22,7 @@ public:
 
     void Set();
     double Step();
-    void ResetGameTime();
+    void ResetGameTime(double seconds={});
     void SkipGameTime(double seconds);
 
     double Delta() const;
diff --git a/StarsEx/CmdIntelDlg.cpp b/StarsEx/CmdIntelDlg.cpp
index fb0c83b..f7ed247 100644
--- a/StarsEx/CmdIntelDlg.cpp
+++ b/StarsEx/CmdIntelDlg.cpp
@@ -49,15 +49,11 @@ DEF_MAP_CLIENT(CmdIntelDlg, OnPlay);
 
 CmdIntelDlg::CmdIntelDlg(Screen* s, FormDef& def, CmpnScreen* mgr)
     : FormWindow(s, 0, 0, s->Width(), s->Height()), CmdDlg(mgr), manager(mgr),
-      stars(0), campaign(0), update_time(0), start_scene(0),
+      stars(0), campaign(0), start_scene(0),
       cam_view(0), dsp_view(0)
 {
     stars    = Starshatter::GetInstance();
     campaign = Campaign::GetCampaign();
-
-    if (campaign)
-    update_time = campaign->GetUpdateTime();
-
     Init(def);
 }
 
@@ -140,15 +136,12 @@ CmdIntelDlg::ExecFrame()
 {
     CmdDlg::ExecFrame();
 
-    if (campaign != Campaign::GetCampaign() || campaign->GetUpdateTime() != update_time) {
-        campaign    = Campaign::GetCampaign();
-        update_time = campaign->GetUpdateTime();
-
+    if (campaign != Campaign::GetCampaign()) {
+        campaign = Campaign::GetCampaign();
         lst_news->ClearItems();
         txt_news->SetText("");
-
         if (img_news)
-        img_news->SetPicture(bmp_default);
+            img_news->SetPicture(bmp_default);
     }
 
     if (campaign) {
diff --git a/StarsEx/CmdIntelDlg.h b/StarsEx/CmdIntelDlg.h
index 8ff5fe7..98bae4f 100644
--- a/StarsEx/CmdIntelDlg.h
+++ b/StarsEx/CmdIntelDlg.h
@@ -66,7 +66,6 @@ protected:
 
     Starshatter*      stars;
     Campaign*         campaign;
-    double            update_time;
     int               start_scene;
     Text              event_scene;
 };
diff --git a/StarsEx/CmpSelectDlg.cpp b/StarsEx/CmpSelectDlg.cpp
index 941c53a..028dc17 100644
--- a/StarsEx/CmpSelectDlg.cpp
+++ b/StarsEx/CmpSelectDlg.cpp
@@ -23,6 +23,7 @@
 #include "CombatGroup.h"
 #include "ShipDesign.h"
 #include "Player.h"
+#include "Stardate.h"
 
 #include "Clock.h"
 #include "ContentBundle.h"
@@ -147,14 +148,9 @@ CmpSelectDlg::ExecFrame()
                     campaign->Description());
                 }
                 else {
-                    char time_buf[32];
                     char score_buf[32];
-
-                    double t = campaign->GetLoadTime() - campaign->GetStartTime();
-                    FormatDayTime(time_buf, t);
-
+                    const auto load_time = starshatter::engine::Stardate{campaign->LoadTime()}.Format();
                     sprintf_s(score_buf, "%d", campaign->GetPlayerTeamScore());
-
                     Text desc = Text("<font Limerick12><color ffffff>") +
                     campaign->Name() +
                     Text("<font Verdana>\n\n") +
@@ -165,7 +161,7 @@ CmpSelectDlg::ExecFrame()
                     Text("\n\n<color ffff80>") +
                     ContentBundle::GetInstance()->GetText("CmpSelectDlg.campaign-time") +
                     Text("<color ffffff>\n\t") +
-                    time_buf +
+                    load_time +
                     Text("\n\n<color ffff80>") +
                     ContentBundle::GetInstance()->GetText("CmpSelectDlg.assignment") +
                     Text("<color ffffff>\n\t");
diff --git a/StarsEx/Mission.cpp b/StarsEx/Mission.cpp
index 2350a8d..f794335 100644
--- a/StarsEx/Mission.cpp
+++ b/StarsEx/Mission.cpp
@@ -1409,6 +1409,8 @@ Mission::Serialize(const char* player_elem, int player_index)
         s += "\"\n\n";
     }
 
+    s += Text::format("stardate: %.1Lf\n", Stardate());
+
     char buffer[256];
     FormatTime(buffer, Start());
 
diff --git a/StarsEx/Mission.h b/StarsEx/Mission.h
index 5bcffa7..0b8c0a6 100644
--- a/StarsEx/Mission.h
+++ b/StarsEx/Mission.h
@@ -104,7 +104,7 @@ public:
     const char*          Objective()     const { return objective;    }
     const char*          Subtitles()     const;
     int                  Start()         const { return start;        }
-    double               Stardate()      const { return stardate;     }
+    long double          Stardate()      const { return stardate;     }
     int                  Type()          const { return type;         }
     const char*          TypeName()      const { return RoleName(type); }
     int                  Team()          const { return team;         }
@@ -174,7 +174,7 @@ protected:
     int                  type;
     int                  team;
     int                  start;
-    double               stardate;
+    long double          stardate;
     bool                 ok;
     bool                 active;
     bool                 complete;
diff --git a/StarsEx/MsnSelectDlg.cpp b/StarsEx/MsnSelectDlg.cpp
index 8c720c8..1f61d9a 100644
--- a/StarsEx/MsnSelectDlg.cpp
+++ b/StarsEx/MsnSelectDlg.cpp
@@ -12,25 +12,27 @@
 */
 
 #include "MsnSelectDlg.h"
-#include "MsnEditDlg.h"
-#include "MsnEditNavDlg.h"
-#include "ConfirmDlg.h"
-#include "MenuScreen.h"
-#include "Starshatter.h"
-#include "Campaign.h"
-#include "Mission.h"
 
-#include "Game.h"
-#include "ContentBundle.h"
 #include "Button.h"
+#include "Campaign.h"
+#include "Clock.h"
 #include "ComboBox.h"
-#include "ListBox.h"
-#include "Slider.h"
-#include "Video.h"
+#include "ConfirmDlg.h"
+#include "ContentBundle.h"
+#include "FormatUtil.h"
+#include "Game.h"
 #include "Keyboard.h"
+#include "ListBox.h"
+#include "MenuScreen.h"
+#include "Mission.h"
 #include "Mouse.h"
+#include "MsnEditDlg.h"
+#include "MsnEditNavDlg.h"
 #include "ParseUtil.h"
-#include "FormatUtil.h"
+#include "Slider.h"
+#include "Stardate.h"
+#include "Starshatter.h"
+#include "Video.h"
 
 // +--------------------------------------------------------------------+
 // DECLARE MAPPING FUNCTIONS:
@@ -393,6 +395,9 @@ MsnSelectDlg::OnNew(AWEvent* event)
         navdlg->SetMission(info->mission);
         navdlg->SetMissionInfo(info);
     }
+    starshatter::engine::SetOperationStart(info->mission->Stardate());
+    starshatter::engine::SetMissionStart(info->mission->Start());
+    Clock::GetInstance()->ResetGameTime();
 }
 
 void
@@ -418,6 +423,9 @@ MsnSelectDlg::OnEdit(AWEvent* event)
 
         editor->SetMissionInfo(c->GetMissionInfo(mission_id));
         editor->SetMission(m);
+        starshatter::engine::SetOperationStart(m->Stardate());
+        starshatter::engine::SetMissionStart(m->Start());
+        Clock::GetInstance()->ResetGameTime();
         manager->ShowMsnEditDlg();
     }
 }
@@ -479,11 +487,13 @@ MsnSelectDlg::OnAccept(AWEvent* event)
 {
     if (selected_mission >= 0) {
         Mouse::Show(false);
-
-        int id = campaign->GetMissionList()[selected_mission]->id;
+        const auto id = campaign->GetMissionList()[selected_mission]->id;
         campaign->SetMissionId(id);
         campaign->ReloadMission(id);
-
+        const auto* mission = campaign->GetMission();
+        starshatter::engine::SetOperationStart(mission->Stardate());
+        starshatter::engine::SetMissionStart(mission->Start());
+        Clock::GetInstance()->ResetGameTime();
         stars->SetGameMode(Game::PREP_MODE);
     }
 }
diff --git a/StarsEx/NetUnitDlg.cpp b/StarsEx/NetUnitDlg.cpp
index 26b2af7..d9d7144 100644
--- a/StarsEx/NetUnitDlg.cpp
+++ b/StarsEx/NetUnitDlg.cpp
@@ -12,27 +12,27 @@
 */
 
 #include "NetUnitDlg.h"
-#include "NetClientConfig.h"
+
+#include "Campaign.h"
+#include "Campaign.h"
+#include "Clock.h"
 #include "ConfirmDlg.h"
+#include "ContentBundle.h"
+#include "Keyboard.h"
 #include "MenuScreen.h"
-#include "Starshatter.h"
-#include "Campaign.h"
 #include "Mission.h"
-#include "Ship.h"
-#include "Player.h"
-#include "Campaign.h"
-#include "ShipDesign.h"
-
 #include "NetAddr.h"
+#include "NetChat.h"
+#include "NetClientConfig.h"
 #include "NetLobbyClient.h"
 #include "NetLobbyServer.h"
 #include "NetUser.h"
-#include "NetChat.h"
-
-#include "ContentBundle.h"
+#include "Player.h"
+#include "ShipDesign.h"
+#include "Ship.h"
+#include "Stardate.h"
+#include "Starshatter.h"
 #include "Video.h"
-#include "Keyboard.h"
-#include "Clock.h"
 
 // +--------------------------------------------------------------------+
 // DECLARE MAPPING FUNCTIONS:
@@ -619,6 +619,9 @@ NetUnitDlg::OnApply(AWEvent* event)
         Mission*  mission = net_lobby->GetSelectedMission();
 
         if (mission) {
+            starshatter::engine::SetOperationStart(mission->Stardate());
+            starshatter::engine::SetMissionStart(mission->Start());
+            Clock::GetInstance()->ResetGameTime();
             net_lobby->GameStart();
             ok = true;
         }
diff --git a/StarsEx/Player.cpp b/StarsEx/Player.cpp
index fffa9a6..091c808 100644
--- a/StarsEx/Player.cpp
+++ b/StarsEx/Player.cpp
@@ -635,19 +635,17 @@ Player::CommandRankRequired(int ship_class)
 // +-------------------------------------------------------------------+
 
 int
-Player::GetMissionPoints(ShipStats* s, std::uint32_t start_time)
+Player::GetMissionPoints(ShipStats* s, std::int_fast32_t flight_time_)
 {
     int result = 0;
 
     if (s) {
         result = s->GetPoints();
 
-        int flight_time = (Clock::GetInstance()->GameTime() - start_time) / 1000;
-
         // if player survived mission, award one experience point
         // for each minute of action, in ten point blocks:
         if (!s->GetDeaths() && !s->GetColls()) {
-            int minutes = flight_time / 60;
+            int minutes = flight_time_ / 60;
             minutes /= 10;
             minutes *= 10;
             result += minutes;
@@ -669,12 +667,12 @@ Player::GetMissionPoints(ShipStats* s, std::uint32_t start_time)
 // +-------------------------------------------------------------------+
 
 void
-Player::ProcessStats(ShipStats* s, std::uint32_t start_time)
+Player::ProcessStats(ShipStats* s, std::int_fast32_t flight_time_)
 {
     if (!s) return;
 
     int old_rank = Rank();
-    int pts      = GetMissionPoints(s, start_time);
+    int pts      = GetMissionPoints(s, flight_time_);
 
     AddPoints(pts);
     AddPoints(s->GetCommandPoints());
@@ -683,7 +681,7 @@ Player::ProcessStats(ShipStats* s, std::uint32_t start_time)
     AddLosses(s->GetDeaths());
     AddLosses(s->GetColls());
     AddMissions(1);
-    AddFlightTime((Clock::GetInstance()->GameTime() - start_time) / 1000);
+    AddFlightTime(flight_time_);
 
     int rank = Rank();
 
diff --git a/StarsEx/Player.h b/StarsEx/Player.h
index c0a9b6c..62e8700 100644
--- a/StarsEx/Player.h
+++ b/StarsEx/Player.h
@@ -116,8 +116,8 @@ public:
     Text           EncodeStats();
     void           DecodeStats(const char* stats);
 
-    int            GetMissionPoints(ShipStats* stats, std::uint32_t start_time);
-    void           ProcessStats(ShipStats* stats, std::uint32_t start_time);
+    int            GetMissionPoints(ShipStats* stats, std::int_fast32_t flight_time_);
+    void           ProcessStats(ShipStats* stats, std::int_fast32_t flight_time_);
     bool           EarnedAward(AwardInfo* a, ShipStats* s);
 
     static const char*   RankName(int rank);
diff --git a/StarsEx/Sim.cpp b/StarsEx/Sim.cpp
index bdf843b..f938b7a 100644
--- a/StarsEx/Sim.cpp
+++ b/StarsEx/Sim.cpp
@@ -71,6 +71,7 @@
 #include "Solid.h"
 #include "Sound.h"
 #include "Sprite.h"
+#include "Stardate.h"
 #include "Starshatter.h"
 #include "StarSystem.h"
 #include "Terrain.h"
@@ -122,8 +123,7 @@ Sim*        Sim::sim    = 0;
 
 Sim::Sim(MotionController* c)
     : ctrl(c), test_mode(false), grid_shown(false), dust(0),
-      star_system(0), active_region(0), mission(0), netgame(0),
-      start_time(0)
+      star_system(0), active_region(0), mission(0), netgame(0)
 {
     Drive::Initialize();
     Explosion::Initialize();
@@ -206,7 +206,7 @@ Sim::CommitMission()
 
             if (s->IsPlayer()) {
                 Player* p = Player::GetCurrentPlayer();
-                p->ProcessStats(s, start_time);
+                p->ProcessStats(s, starshatter::engine::MissionTime());
 
                 if (mission && mission->Type() == Mission::TRAINING &&
                         s->GetDeaths() == 0 && s->GetColls() == 0)
@@ -368,8 +368,10 @@ Sim::ExecMission()
     if (cam_dir)
     cam_dir->Reset();
 
-    if (mission->Stardate() > 0)
-    StarSystem::SetBaseTime(mission->Stardate(), true);
+    if (mission->Stardate() > 0.0l)
+        starshatter::engine::SetOperationStart(mission->Stardate());
+    starshatter::engine::SetMissionStart(mission->Start());
+    Clock::GetInstance()->ResetGameTime();
 
     star_system = mission->GetStarSystem();
     star_system->Activate(scene);
@@ -395,7 +397,6 @@ Sim::ExecMission()
     }
 
     first_frame = true;
-    start_time  = Clock::GetInstance()->GameTime();
 
     AudioConfig::SetTraining(mission->Type() == Mission::TRAINING);
 }
@@ -1896,7 +1897,7 @@ Sim::ProcessEventTrigger(int type, int event_id, const char* ship, int param)
 double
 Sim::MissionClock() const
 {
-    return (Clock::GetInstance()->GameTime() - start_time) / 1000.0;
+    return starshatter::engine::MissionTime();
 }
 
 // +--------------------------------------------------------------------+
@@ -1931,7 +1932,7 @@ Sim::SkipCutscene()
             }
         }
 
-        double skip_time = end_time - MissionClock();
+        const auto skip_time = end_time - MissionClock();
         if (skip_time > 0) {
             Clock::GetInstance()->SkipGameTime(skip_time);
         }
diff --git a/StarsEx/StarSystem.cpp b/StarsEx/StarSystem.cpp
index b8340f6..6641b63 100644
--- a/StarsEx/StarSystem.cpp
+++ b/StarsEx/StarSystem.cpp
@@ -12,71 +12,31 @@
 */
 
 #include "StarSystem.h"
-#include "Galaxy.h"
-#include "Sky.h"
-#include "Starshatter.h"
-#include "TerrainRegion.h"
-#include "TerrainHaze.h"
-#include "Weather.h"
 
+#include "Bitmap.h"
+#include "Clock.h"
+#include "DataLoader.h"
+#include "Galaxy.h"
 #include "Game.h"
 #include "GameWinDX9.h"
-#include "Clock.h"
-#include "Sound.h"
-#include "Solid.h"
 #include "Light.h"
-#include "Bitmap.h"
-#include "DataLoader.h"
-#include "Scene.h"
 #include "ParseUtil.h"
+#include "Scene.h"
+#include "Sky.h"
+#include "Solid.h"
+#include "Sound.h"
+#include "Stardate.h"
+#include "Starshatter.h"
+#include "TerrainHaze.h"
+#include "TerrainRegion.h"
 #include "Video.h"
-
-const long double epoch = 0.5e9;
-long double StarSystem::stardate = 0;
+#include "Weather.h"
 
 // +====================================================================+
 
-static long double base_time = 0;
 static WORD   oldcw = 0;
 static WORD   fpcw  = 0;
 
-void StarSystem::SetBaseTime(long double t, bool absolute)
-{
-    if (absolute) {
-        base_time = t;
-        CalcStardate();
-    }
-
-    else if (t > 0) {
-        if (t > epoch) t -= epoch;
-        base_time = t;
-        CalcStardate();
-    }
-}
-
-long double StarSystem::GetBaseTime()
-{
-    return base_time;
-}
-
-void StarSystem::CalcStardate()
-{
-    if (base_time < 1) {
-        time_t clock_seconds;
-        time(&clock_seconds);
-
-        base_time = clock_seconds;
-
-        while (base_time < 0)
-        base_time += epoch;
-    }
-
-    long double gtime = Clock::GetInstance()->GameTime<long double>() / 1000.0;
-    long double sdate = gtime + base_time + epoch;
-
-    stardate = sdate;
-}
-
 static const double GRAV    = 6.673e-11;
 static const int    NAMELEN = 64;
 
@@ -119,7 +79,6 @@ static OrbitalBody*   primary_moon   = 0;
 void
 StarSystem::Load()
 {
-    CalcStardate();
     active_region = 0;
 
     BYTE*       block  = 0;
@@ -1386,8 +1345,6 @@ static BYTE min3(BYTE a, BYTE b, BYTE c)
 void
 StarSystem::ExecFrame()
 {
-    CalcStardate();
-
     ListIter<OrbitalBody> star = bodies;
     while (++star)
     star->Update();
@@ -1843,7 +1800,7 @@ Orbital::Update()
         double grade = (retro) ? -1 : 1;
 
         // orbits are counter clockwise:
-        phase = -2 * PI * grade * StarSystem::Stardate() / period;
+        phase = PI * -2.0 * grade * starshatter::engine::CurrentTime() / period;
 
         loc = primary->Location() + Point((double) (orbit * cos(phase)),
         (double) (orbit * sin(phase)),
@@ -1871,7 +1828,7 @@ Orbital::PredictLocation(double delta_t)
         double grade = (retro) ? -1 : 1;
 
         // orbits are(?) counter clockwise:
-        double predicted_phase = (double) (-2 * PI * grade * (StarSystem::Stardate()+delta_t) / period);
+        const auto predicted_phase = PI * -2.0 * grade * (starshatter::engine::CurrentTime() + delta_t) / period;
 
         predicted_loc += Point((double) (orbit * cos(predicted_phase)),
         (double) (orbit * sin(predicted_phase)),
@@ -1917,7 +1874,7 @@ OrbitalBody::Update()
     theta = 0;
 
     if (rotation > 0)
-    theta = -2 * PI * StarSystem::Stardate() / rotation;
+    theta = PI * -2.0 * starshatter::engine::CurrentTime() / rotation;
 
     ListIter<OrbitalBody> body = satellites;
     while (++body)
diff --git a/StarsEx/StarSystem.h b/StarsEx/StarSystem.h
index bdd37ec..6770f4a 100644
--- a/StarsEx/StarSystem.h
+++ b/StarsEx/StarSystem.h
@@ -78,10 +78,6 @@ public:
 
     void              SetActiveRegion(OrbitalRegion* rgn);
 
-    static void        SetBaseTime(long double t, bool absolute=false);
-    static long double GetBaseTime();
-    static long double Stardate()           { return stardate; }
-    static void       CalcStardate();
     double            Radius()       const { return radius;   }
 
     void              SetSunlight(Color color, double brightness=1);
@@ -109,7 +105,6 @@ protected:
     int               affiliation;
     int               seq;
     Point             loc;
-    static long double stardate;
     double            radius;
     bool              instantiated;
 
diff --git a/StarsEx/Stardate.cpp b/StarsEx/Stardate.cpp
new file mode 100644
index 0000000..f57205a
--- /dev/null
+++ b/StarsEx/Stardate.cpp
@@ -0,0 +1,137 @@
+/*  Starshatter: The Open Source Project
+    Copyright (c) 2021-2024, Starshatter: The Open Source Project Contributors
+    Copyright (c) 2011-2012, Starshatter OpenSource Distribution Contributors
+    Copyright (c) 1997-2006, Destroyer Studios LLC.
+*/
+
+#include "Stardate.h"
+
+#include <cstdint>
+
+#include <Text.h>
+
+#include "Clock.h"
+
+
+namespace starshatter
+{
+namespace engine
+{
+
+
+static constexpr long double EPOCH {0.5e9l};
+static constexpr long double MINUTE {60};
+static constexpr long double HOUR {60 * MINUTE};
+static constexpr long double DAY {24 * HOUR};
+static long double operation_start {};
+static long double mission_start {};
+
+
+Stardate::Stardate() :
+	value {0}
+{
+}
+
+
+Stardate::Stardate(long double value_) :
+	value {value_}
+{
+}
+
+
+Stardate::operator long double() const
+{
+	return value;
+}
+
+
+Text
+Stardate::Format(bool short_format) const
+{
+	auto time = value;
+	std::int_fast32_t day = 1, hours = 0, minutes = 0, seconds = 0;
+	while (time >= DAY) {
+		time -= DAY;
+		++day;
+	}
+	while (time >= HOUR) {
+		time -= HOUR;
+		++hours;
+	}
+	while (time >= MINUTE) {
+		time -= MINUTE;
+		++minutes;
+	}
+	seconds = time;
+	return Text::format(
+		short_format ? "%02d/%02d:%02d:%02d" : "Day %d, %02d:%02d:%02d",
+		day, hours, minutes, seconds);
+}
+
+
+Stardate
+CurrentTime()
+{
+	return Epoch() + OperationStart() + OperationTime();
+}
+
+
+Stardate
+OperationTime()
+{
+	return MissionStart() + MissionTime();
+}
+
+
+Stardate
+MissionTime()
+{
+	if (const auto* clock = Clock::GetInstance())
+		return clock->GameTime<long double>() / 1000.0l;
+	throw "game clock not initialized";
+}
+
+
+long double
+Epoch()
+{
+	return EPOCH;
+}
+
+
+long double
+OperationStart()
+{
+	return operation_start;
+}
+
+
+long double
+MissionStart()
+{
+	return mission_start;
+}
+
+
+void
+SetOperationStart(long double value, bool relative)
+{
+	if (relative)
+		operation_start += value;
+	else
+		operation_start = value;
+}
+
+
+void
+SetMissionStart(long double value, bool relative)
+{
+	if (relative)
+		mission_start += value;
+	else
+		mission_start = value;
+}
+
+
+}  // namespace engine
+}  // namespace starshatter
diff --git a/StarsEx/Stardate.h b/StarsEx/Stardate.h
new file mode 100644
index 0000000..cc696c8
--- /dev/null
+++ b/StarsEx/Stardate.h
@@ -0,0 +1,43 @@
+/*  Starshatter: The Open Source Project
+    Copyright (c) 2021-2024, Starshatter: The Open Source Project Contributors
+    Copyright (c) 2011-2012, Starshatter OpenSource Distribution Contributors
+    Copyright (c) 1997-2006, Destroyer Studios LLC.
+*/
+
+#pragma once
+
+#include <Text.h>
+
+
+namespace starshatter
+{
+namespace engine
+{
+
+
+struct Stardate
+{
+	long double value = {};
+
+	Stardate();
+	Stardate(long double value_);
+
+	operator long double() const;
+
+	Text Format(bool short_format=false) const;
+};
+
+
+Stardate CurrentTime();
+Stardate OperationTime();
+Stardate MissionTime();
+
+long double Epoch();
+long double OperationStart();
+long double MissionStart();
+void SetOperationStart(long double value={}, bool relative=false);
+void SetMissionStart(long double value={}, bool relative=false);
+
+
+}  // namespace engine
+}  // namespace starshatter
diff --git a/StarsEx/Starshatter.cpp b/StarsEx/Starshatter.cpp
index 7663148..1a373cc 100644
--- a/StarsEx/Starshatter.cpp
+++ b/StarsEx/Starshatter.cpp
@@ -7,7 +7,6 @@
 
 */
 
-
 #include "Starshatter.h"
 
 #include "MenuScreen.h"
@@ -108,6 +107,7 @@
 #include "Universe.h"
 #include "Video.h"
 #include "VideoSettings.h"
+#include "Stardate.h"
 
 // +--------------------------------------------------------------------+
 
@@ -121,7 +121,9 @@ Starshatter*   Starshatter::instance {nullptr};
 
 static Mission*   current_mission   = 0;
 static Mission*   cutscene_mission  = 0;
-static double     cutscene_basetime = 0;
+static long double cutscene_operation_start = 0;
+static long double cutscene_mission_start = 0;
+static double     cutscene_game_time = 0;
 static int        cut_efx_volume    = 100;
 static int        cut_wrn_volume    = 100;
 static double     time_til_change   = 0;
@@ -592,7 +594,7 @@ Starshatter::SetGameMode(int m)
         Clock::GetInstance()->SetTimeCompression(1.0);
         Pause(false);
 
-        Print("  Stardate: %.1Lf\n", StarSystem::GetBaseTime());
+        Print("  Stardate: %.1Lf\n", starshatter::engine::CurrentTime().value);
     }
 
     else if (m == PLAN_MODE) {
@@ -603,7 +605,7 @@ Starshatter::SetGameMode(int m)
 
             StopNetGame();
             Pause(true);
-            Print("  Stardate: %.1Lf\n", StarSystem::GetBaseTime());
+            Print("  Stardate: %.1Lf\n", starshatter::engine::CurrentTime().value);
         }
     }
 
@@ -630,7 +632,7 @@ Starshatter::SetGameMode(int m)
             StopNetGame();
         }
 
-        Print("  Stardate: %.1Lf\n", StarSystem::GetBaseTime());
+        Print("  Stardate: %.1Lf\n", starshatter::engine::CurrentTime().value);
         Print("  Bitmap Cache Footprint: %d KB\n", Bitmap::CacheMemoryFootprint() / 1024);
 
         paused = true;
@@ -1600,11 +1602,11 @@ Starshatter::DoGameKeys()
 
         /*** For Debug Convenience Only: ***/
         else if (KeyDown(KEY_INC_STARDATE)) {
-            StarSystem::SetBaseTime(StarSystem::GetBaseTime() + 600, true);
+            starshatter::engine::SetOperationStart(300.0, true);
         }
 
         else if (KeyDown(KEY_DEC_STARDATE)) {
-            StarSystem::SetBaseTime(StarSystem::GetBaseTime() - 600, true);
+            starshatter::engine::SetOperationStart(-300.0, true);
         }
         /***/
     }
@@ -2556,7 +2558,9 @@ Starshatter::ExecCutscene(const char* msn_file, const char* path)
     CreateWorld();
 
     cutscene_mission  = new Mission(0);
-    cutscene_basetime = StarSystem::GetBaseTime();
+    cutscene_operation_start = starshatter::engine::OperationStart();
+    cutscene_mission_start = starshatter::engine::MissionStart();
+    cutscene_game_time = Clock::GetInstance()->GameTime<double>() / 1000.0;
 
     if (cutscene_mission->Load(msn_file, path)) {
         Sim* sim = (Sim*) world;
@@ -2582,7 +2586,9 @@ Starshatter::ExecCutscene(const char* msn_file, const char* path)
     else {
         delete cutscene_mission;
         cutscene_mission  = 0;
-        cutscene_basetime = 0;
+        cutscene_operation_start = 0;
+        cutscene_mission_start = 0;
+        cutscene_game_time = 0;
     }
 }
 
@@ -2659,15 +2665,14 @@ Starshatter::EndMission()
         if (sim && sim->GetMission() == cutscene_mission) {
             ShipStats::Initialize();
             sim->UnloadMission();
-
-            // restore world clock (true => absolute time reference)
-            if (cutscene_basetime != 0)
-            StarSystem::SetBaseTime(cutscene_basetime, true);
-
+            starshatter::engine::SetOperationStart(cutscene_operation_start);
+            starshatter::engine::SetMissionStart(cutscene_mission_start);
+            Clock::GetInstance()->ResetGameTime(cutscene_game_time);
             delete cutscene_mission;
-            cutscene_mission  = 0;
-            cutscene_basetime = 0;
-
+            cutscene_mission = nullptr;
+            cutscene_operation_start = 0;
+            cutscene_mission_start = 0;
+            cutscene_game_time = 0;
             return;
         }
     }
diff --git a/StarsEx/Weather.cpp b/StarsEx/Weather.cpp
index 8d3ded6..ffbdaff 100644
--- a/StarsEx/Weather.cpp
+++ b/StarsEx/Weather.cpp
@@ -12,9 +12,9 @@
 */
 
 #include "Weather.h"
-#include "StarSystem.h"
-#include "Game.h"
+
 #include "ContentBundle.h"
+#include "Stardate.h"
 
 // +--------------------------------------------------------------------+
 
@@ -94,7 +94,7 @@ Weather::Update()
 {
     NormalizeChances();
 
-    double weather = (sin(StarSystem::Stardate() * 2 * PI / period)+1)/2;
+    const auto weather = (sin(starshatter::engine::CurrentTime() * 2.0 * PI / period) + 1.0) / 2.0;
 
     state = active_states[0];
 
diff --git a/StarsEx/test/Stardate.cpp b/StarsEx/test/Stardate.cpp
new file mode 100644
index 0000000..fb95562
--- /dev/null
+++ b/StarsEx/test/Stardate.cpp
@@ -0,0 +1,60 @@
+#include <gtest/gtest.h>
+
+#include <Clock.h>
+#include <Stardate.h>
+
+namespace ng = starshatter::engine;
+
+
+TEST(StarsEx, MissionTimeIsGameTime)
+{
+	ASSERT_TRUE(Clock::Init());
+	auto* clock = Clock::GetInstance();
+	EXPECT_NEAR(0.0l, ng::MissionTime(), 0.001l);
+	clock->SkipGameTime(0.05);
+	EXPECT_NEAR(0.05l, ng::MissionTime(), 0.001l);
+	clock->SkipGameTime(0.05);
+	EXPECT_NEAR(0.10l, ng::MissionTime(), 0.001l);
+	Clock::Close();
+}
+
+
+TEST(StarsEx, OperationTimeIsMissionOffset)
+{
+	ASSERT_TRUE(Clock::Init());
+	auto* clock = Clock::GetInstance();
+	EXPECT_NEAR(0.0l, ng::OperationTime(), 0.001l);
+	ng::SetMissionStart(1000.0l);
+	EXPECT_NEAR(1000.0l, ng::OperationTime(), 0.001l);
+	clock->SkipGameTime(0.05);
+	EXPECT_NEAR(1000.05l, ng::OperationTime(), 0.001l);
+	ng::SetMissionStart(1000.0l, true);
+	EXPECT_NEAR(2000.05l, ng::OperationTime(), 0.001l);
+	Clock::Close();
+}
+
+
+TEST(StarsEx, CurrentTimeIsOperationAndEpoch)
+{
+	ASSERT_TRUE(Clock::Init());
+	auto* clock = Clock::GetInstance();
+	EXPECT_NEAR(ng::Epoch(), ng::CurrentTime(), 0.001l);
+	ng::SetOperationStart(1000.0l);
+	EXPECT_NEAR(ng::Epoch() + 1000.0l, ng::CurrentTime(), 0.001l);
+	ng::SetMissionStart(500.0l);
+	EXPECT_NEAR(ng::Epoch() + 1500.0l, ng::CurrentTime(), 0.001l);
+	clock->SkipGameTime(0.05);
+	EXPECT_NEAR(ng::Epoch() + 1500.05l, ng::CurrentTime(), 0.001l);
+	ng::SetOperationStart(1000.0l, true);
+	EXPECT_NEAR(ng::Epoch() + 2500.05l, ng::CurrentTime(), 0.001l);
+	Clock::Close();
+}
+
+
+TEST(StarsEx, FormatOperationTime)
+{
+	ASSERT_TRUE(Clock::Init());
+	auto* clock = Clock::GetInstance();
+	EXPECT_EQ("Day 1, 00:00:00", ng::OperationTime().Format());
+	Clock::Close();
+}