Fix bug where vessels can remain in situation Splashed.

GameData/KSPCommunityFixes/Settings.cfg

@@ -84,6 +84,11 @@ KSP_COMMUNITY_FIXES
   // it depends on the stock delta V implementation.
   DeltaVHideWhenDisabled = true
 
+  // Fixes an issue where if a vessel starts out splashed, and decouples from its only
+  // splashed parts, it will never leave the splashed state.
+  // This also fixes an issue where Splashed overrides Prelaunch as a Situation.
+  StickySplashedFixer = true
+
   // Fix the asteroid/comet spawner generating non-unique Part.flightId identifiers. This has 
   // a few minor side effects in stock (mainly incorrect science bonuses), but this field is 
   // heavily relied upon by various mods and this can cause major issues for them.

KSPCommunityFixes/BugFixes/StickySplashedFixer.cs

@@ -0,0 +1,141 @@
+/*
+The core of the issue is the asteroid/comet spawner passing a random int for the "id" argument of the ProtoVessel.CreatePartNode() method.
+This id is affected to the part.flightId field, which must be unique game-wide and should have been generated by calling 
+ShipConstruction.GetUniqueFlightID(). Failing to produce an unique flightId result in various issues, especially with mods as they often
+rely on that id.
+
+Note that by fixing this, we replace how the asteroid/comet "seed" is generated, which technically affect further calls to UnityEngine.Random(),
+but this shouldn't have any effect on the actual randomness/distribution of the generated stuff.
+*/
+
+using System;
+using System.Collections.Generic;
+using HarmonyLib;
+using KSP.UI.Screens;
+
+namespace KSPCommunityFixes.BugFixes
+{
+    class StickySplashedFixer : BasePatch
+    {
+        protected override Version VersionMin => new Version(1, 8, 0);
+
+        protected override void ApplyPatches(List<PatchInfo> patches)
+        {
+            patches.Add(new PatchInfo(
+                PatchMethodType.Prefix,
+                AccessTools.Method(typeof(Vessel), "updateSituation"),
+                this));
+
+            patches.Add(new PatchInfo(
+                PatchMethodType.Prefix,
+                AccessTools.Method(typeof(Part), "Die"),
+                this));
+
+            patches.Add(new PatchInfo(
+                PatchMethodType.Postfix,
+                AccessTools.Method(typeof(Part), "Die"),
+                this));
+
+            patches.Add(new PatchInfo(
+                PatchMethodType.Prefix,
+                AccessTools.Method(typeof(Part), "decouple"),
+                this));
+
+            patches.Add(new PatchInfo(
+                PatchMethodType.Postfix,
+                AccessTools.Method(typeof(Part), "decouple"),
+                this));
+        }
+
+        static bool Vessel_updateSituation_Prefix(Vessel __instance)
+        {
+			bool evaOnLadderOnOtherVessel;
+            if (__instance.EVALadderVessel != __instance)
+            {
+                __instance.situation = __instance.evaController.LadderPart.vessel.situation;
+                evaOnLadderOnOtherVessel = true;
+            }
+            else
+            {
+                evaOnLadderOnOtherVessel = false;
+                if (__instance.situation == Vessel.Situations.PRELAUNCH)
+                {
+                    // Slower speed for leaving prelaunch in water since, well, boats are slow.
+                    if (__instance.srfSpeed > (__instance.Splashed ? 1 : 2.5) && !__instance.precalc.isEasingGravity && !__instance.vesselSpawning)
+                        __instance.situation = __instance.Splashed ? Vessel.Situations.SPLASHED : Vessel.Situations.LANDED;
+                }
+                else if (__instance.Landed)
+                {
+                    __instance.situation = Vessel.Situations.LANDED;
+                }
+                else if (__instance.Splashed)
+                {
+                    __instance.situation = Vessel.Situations.SPLASHED;
+                }
+                else
+                {
+                    if (__instance.staticPressurekPa > 0.0)
+                    {
+                        __instance.situation = Vessel.Situations.FLYING;
+                    }
+                    else if (__instance.orbit.eccentricity < 1.0 && __instance.orbit.ApR < __instance.mainBody.sphereOfInfluence)
+                    {
+                        if (__instance.orbit.PeA < (__instance.mainBody.atmosphere ? __instance.mainBody.atmosphereDepth : 0))
+                        {
+                            __instance.situation = Vessel.Situations.SUB_ORBITAL;
+                        }
+                        else
+                        {
+                            __instance.situation = Vessel.Situations.ORBITING;
+                        }
+                    }
+                    else
+                    {
+                        __instance.situation = Vessel.Situations.ESCAPING;
+                    }
+                }
+            }
+
+            if (__instance.situation != __instance.lastSituation)
+            {
+                GameEvents.onVesselSituationChange.Fire(new GameEvents.HostedFromToAction<Vessel, Vessel.Situations>(__instance, __instance.lastSituation, __instance.situation));
+                __instance.lastSituation = __instance.situation;
+            }
+
+            if (__instance.wasLadder != evaOnLadderOnOtherVessel)
+            {
+                __instance.wasLadder = evaOnLadderOnOtherVessel;
+            }
+
+            return false;
+        }
+
+        // We could optimize the below by setting up a coroutine that runs later in the frame
+        // so a vessel isn't processed more than once if, say, multiple parts detach on the
+        // same frame. But the landed/splash check isn't very expensive so I'm not worried.
+
+        static void Part_die_Prefix(Part __instance, out Vessel __state)
+        {
+            __state = __instance.vessel;
+        }
+
+        static void Part_die_Postfix(Part __instance, Vessel __state)
+        {
+            if (__state.IsNotNullOrDestroyed())
+                __state.UpdateLandedSplashed();
+        }
+
+        static void Part_Decouple_Prefix(Part __instance, out Vessel __state)
+        {
+            __state = __instance.vessel;
+        }
+
+        static void Part_Decouple_Postfix(Part __instance, Vessel __state)
+        {
+            if (__state.IsNotNullOrDestroyed())
+                __state.UpdateLandedSplashed();
+
+            // New vessel (on __instance) will run Initialize.
+        }
+    }
+}

KSPCommunityFixes/KSPCommunityFixes.csproj

@@ -91,6 +91,7 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="BasePatch.cs" />
+    <Compile Include="BugFixes\StickySplashedFixer.cs" />
     <Compile Include="BugFixes\AsteroidSpawnerUniqueFlightId.cs" />
     <Compile Include="BugFixes\AutoStrutDrift.cs" />
     <Compile Include="BugFixes\DockingPortRotationDriftAndFixes.cs" />