Added static RNGseed control

src/d_main.cpp

@@ -1993,6 +1993,13 @@ static void D_DoomInit()
 
 	SetLanguageIDs ();
 
+	const char *v = Args->CheckValue("-rngseed");
+	if (v)
+	{
+		rngseed = staticrngseed = atoi(v);
+		use_staticrng = true;
+	}
+	else
 		rngseed = I_MakeRNGSeed();
 	FRandom::StaticClearRandom ();
 

src/g_level.cpp

@@ -408,7 +408,11 @@ void G_InitNew (const char *mapname, bool bTitleLevel)
 
 	if (!savegamerestore)
 	{
-		if (!netgame)
+		if (use_staticrng)
+		{
+			rngseed = staticrngseed;
+		}
+		else if (!netgame)
 		{ // [RH] Change the random seed for each new single player game
 			rngseed = rngseed + 1;
 		}

src/m_random.cpp

@@ -96,6 +96,42 @@ FRandom M_Random;
 // Global seed. This is modified predictably to initialize every RNG.
 DWORD rngseed;
 
+// Static RNG marker. This is only used when the RNG is set for each new game.
+DWORD staticrngseed;
+bool use_staticrng;
+
+// Allows checking or staticly setting the global seed.
+CCMD(rngseed)
+{
+	if (argv.argc() == 1)
+	{
+		Printf("Usage: rngseed get|set|clear\n");
+		return;
+	}
+	if (stricmp(argv[1], "get") == 0)
+	{
+		Printf("rngseed is %d\n", rngseed);
+	}
+	else if (stricmp(argv[1], "set") == 0)
+	{
+		if (argv.argc() == 2)
+		{
+			Printf("You need to specify a value to set\n");
+		}
+		else
+		{
+			staticrngseed = atoi(argv[2]);
+			use_staticrng = true;
+			Printf("Static rngseed %d will be set for next game\n", staticrngseed);
+		}
+	}
+	else if (stricmp(argv[1], "clear") == 0)
+	{
+		use_staticrng = false;
+		Printf("Static rngseed cleared\n");
+	}
+}
+
 // PRIVATE DATA DEFINITIONS ------------------------------------------------
 
 FRandom *FRandom::RNGList;

src/m_random.h

@@ -215,6 +215,10 @@ private:
 
 extern DWORD rngseed;			// The starting seed (not part of state)
 
+extern DWORD staticrngseed;		// Static rngseed that can be set by the user
+extern bool use_staticrng;
+
+
 // M_Random can be used for numbers that do not affect gameplay
 extern FRandom M_Random;