From d6af8dc352f2f87bcbeda11f932a6fbc574fe883 Mon Sep 17 00:00:00 2001
From: Edward Richardson <Edward850@crantime.org>
Date: Sat, 3 May 2014 02:11:16 +1200
Subject: [PATCH] Added static RNGseed control

---
 src/d_main.cpp   |  9 ++++++++-
 src/g_level.cpp  |  6 +++++-
 src/m_random.cpp | 36 ++++++++++++++++++++++++++++++++++++
 src/m_random.h   |  4 ++++
 4 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/src/d_main.cpp b/src/d_main.cpp
index 6c938ef53f..f677f88b32 100644
--- a/src/d_main.cpp
+++ b/src/d_main.cpp
@@ -1993,7 +1993,14 @@ static void D_DoomInit()
 
 	SetLanguageIDs ();
 
-	rngseed = I_MakeRNGSeed();
+	const char *v = Args->CheckValue("-rngseed");
+	if (v)
+	{
+		rngseed = staticrngseed = atoi(v);
+		use_staticrng = true;
+	}
+	else
+		rngseed = I_MakeRNGSeed();
 	FRandom::StaticClearRandom ();
 
 	Printf ("M_LoadDefaults: Load system defaults.\n");
diff --git a/src/g_level.cpp b/src/g_level.cpp
index 65bde08d88..c721be4e1e 100644
--- a/src/g_level.cpp
+++ b/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;
 		}
diff --git a/src/m_random.cpp b/src/m_random.cpp
index 7634101113..f1e39faf94 100644
--- a/src/m_random.cpp
+++ b/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;
diff --git a/src/m_random.h b/src/m_random.h
index 5b124c50ea..b5e21c63c9 100644
--- a/src/m_random.h
+++ b/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;