levelheader_t: relevantskin property

- On level load for GT_TUTORIAL:
    - Forces to requested skin (or Eggman if not specified).
        - Named `relevantskin` and not `tutorialskin` in case it's useful to use the same apparatus later for Adventure.
    - Also sets default skincolor and disables follower.

src/deh_soc.c

@@ -1122,6 +1122,11 @@ void readlevelheader(MYFILE *f, char * name)
 				deh_strlcpy(mapheaderinfo[num]->zonttl, word2,
 					sizeof(mapheaderinfo[num]->zonttl), va("Level header %d: zonetitle", num));
 			}
+			else if (fastcmp(word, "RELEVANTSKIN"))
+			{
+				deh_strlcpy(mapheaderinfo[num]->relevantskin, word2,
+					sizeof(mapheaderinfo[num]->relevantskin), va("Level header %d: relevantskin", num));
+			}
 			else if (fastcmp(word, "SCRIPTNAME"))
 			{
 				deh_strlcpy(mapheaderinfo[num]->scriptname, word2,

src/doomstat.h

@@ -427,6 +427,7 @@ struct mapheader_t
 	UINT32 typeoflevel;					///< Combination of typeoflevel flags.
 	UINT8 numlaps;						///< Number of laps in circuit mode, unless overridden.
 	fixed_t gravity;					///< Map-wide gravity.
+	char relevantskin[SKINNAMESIZE+1];	///< Skin to use for tutorial (if not provided, uses Eggman.)
 
 	// Music information
 	char musname[MAXMUSNAMES][7];		///< Music tracks to play. First dimension is the track number, second is the music string. "" for no music.

src/p_setup.c

@@ -389,6 +389,7 @@ static void P_ClearSingleMapHeaderInfo(INT16 num)
 	mapheaderinfo[num]->typeoflevel = 0;
 	mapheaderinfo[num]->gravity = DEFAULT_GRAVITY;
 	mapheaderinfo[num]->keywords[0] = '\0';
+	mapheaderinfo[num]->relevantskin[0] = '\0';
 	mapheaderinfo[num]->musname[0][0] = 0;
 	mapheaderinfo[num]->musname_size = 0;
 	mapheaderinfo[num]->positionmus[0] = '\0';
@@ -7392,6 +7393,27 @@ static void P_InitCamera(void)
 static void P_InitPlayers(void)
 {
 	UINT8 i;
+	INT32 skin = -1;
+
+	// Are we forcing a character?
+	if (gametype == GT_TUTORIAL)
+	{
+		// Get skin from name.
+		if (mapheaderinfo[gamemap-1] && mapheaderinfo[gamemap-1]->relevantskin[0])
+		{
+			skin = R_SkinAvailable(mapheaderinfo[gamemap-1]->relevantskin);
+		}
+		else
+		{
+			skin = R_SkinAvailable(DEFAULTSKIN);
+		}
+
+		// Handle invalid case.
+		if (skin == -1)
+		{
+			skin = 0;
+		}
+	}
 
 	for (i = 0; i < MAXPLAYERS; i++)
 	{
@@ -7400,6 +7422,15 @@ static void P_InitPlayers(void)
 
 		players[i].mo = NULL;
 
+		// If we're forcing a character, do it now.
+		if (skin != -1)
+		{
+			players[i].skin = skin;
+			players[i].skincolor = skins[skin].prefcolor;
+			players[i].followerskin = -1;
+			// followercolor can be left alone for hopefully obvious reasons
+		}
+
 		if (!(gametyperules & GTR_CIRCUIT) && K_PodiumSequence() == false)
 		{
 			G_DoReborn(i);

src/r_skins.c

@@ -236,6 +236,12 @@ boolean R_SkinUsable(INT32 playernum, INT32 skinnum, boolean demoskins)
 		return true;
 	}
 
+	if (gametype == GT_TUTORIAL)
+	{
+		// Being forced to play as this character by the tutorial
+		return true;
+	}
+
 	// Determine if this character is supposed to be unlockable or not
 	if (useplayerstruct && demo.playback)
 	{