add SpawnMultiCoopOnly mapinfo flag to spawn **only** coop spawns in …

…single-player

src/gamedata/g_mapinfo.h

@@ -510,6 +510,7 @@ enum ESkillProperty
 	SKILLP_PlayerRespawn,
 	SKILLP_SpawnMulti,
 	SKILLP_InstantReaction,
+	SKILLP_SpawnMultiCoopOnly,
 };
 enum EFSkillProperty	// floating point properties
 {
@@ -555,6 +556,7 @@ struct FSkillInfo
 	int SpawnFilter;
 	bool SpawnMulti;
 	bool InstantReaction;
+	bool SpawnMultiCoopOnly;
 	int ACSReturn;
 	FString MenuName;
 	FString PicName;

src/gamedata/g_skill.cpp

@@ -77,6 +77,7 @@ void FMapInfoParser::ParseSkill ()
 	skill.Aggressiveness = 1.;
 	skill.SpawnFilter = 0;
 	skill.SpawnMulti = false;
+	skill.SpawnMultiCoopOnly = false;
 	skill.InstantReaction = false;
 	skill.ACSReturn = 0;
 	skill.MustConfirm = false;
@@ -198,6 +199,10 @@ void FMapInfoParser::ParseSkill ()
 		{
 			skill.SpawnMulti = true;
 		}
+		else if (sc.Compare ("spawnmulticooponly"))
+		{
+			skill.SpawnMultiCoopOnly = true;
+		}
 		else if (sc.Compare ("InstantReaction"))
 		{
 			skill.InstantReaction = true;
@@ -408,9 +413,13 @@ int G_SkillProperty(ESkillProperty prop)
 
 		case SKILLP_SpawnMulti:
 			return AllSkills[gameskill].SpawnMulti;
-
+			
 		case SKILLP_InstantReaction:
 			return AllSkills[gameskill].InstantReaction;
+
+		case SKILLP_SpawnMultiCoopOnly:
+			return AllSkills[gameskill].SpawnMultiCoopOnly;
+
 		}
 	}
 	return 0;
@@ -550,6 +559,7 @@ FSkillInfo &FSkillInfo::operator=(const FSkillInfo &other)
 	SpawnFilter = other.SpawnFilter;
 	SpawnMulti = other.SpawnMulti;
 	InstantReaction = other.InstantReaction;
+	SpawnMultiCoopOnly = other.SpawnMultiCoopOnly;
 	ACSReturn = other.ACSReturn;
 	MenuName = other.MenuName;
 	PicName = other.PicName;

src/playsim/p_mobj.cpp

@@ -5757,6 +5757,7 @@ AActor *FLevelLocals::SpawnMapThing (FMapThing *mthing, int position)
 	AActor *mobj;
 
 	bool spawnmulti = G_SkillProperty(SKILLP_SpawnMulti) || !!(dmflags2 & DF2_ALWAYS_SPAWN_MULTI);
+	bool spawnmulti_cooponly = G_SkillProperty(SKILLP_SpawnMultiCoopOnly);
 
 	if (mthing->EdNum == 0 || mthing->EdNum == -1)
 		return NULL;
@@ -5837,9 +5838,9 @@ AActor *FLevelLocals::SpawnMapThing (FMapThing *mthing, int position)
 		{
 			mask = MTF_COOPERATIVE;
 		}
-		else if (spawnmulti)
+		else if (spawnmulti || spawnmulti_cooponly)
 		{
-			mask = MTF_COOPERATIVE|MTF_SINGLE;
+			mask = spawnmulti_cooponly ? MTF_COOPERATIVE : (MTF_COOPERATIVE|MTF_SINGLE);
 		}
 		else
 		{

wadsrc/static/zscript/constants.zs

@@ -1024,6 +1024,7 @@ enum ESkillProperty
 	SKILLP_PlayerRespawn,
 	SKILLP_SpawnMulti,
 	SKILLP_InstantReaction,
+	SKILLP_SpawnMultiCoopOnly,
 };
 enum EFSkillProperty	// floating point properties
 {