From 2e0e0a3856cda84dd867ed3dc5ca30701e2233f8 Mon Sep 17 00:00:00 2001
From: mazmazz <mar.marcoz@outlook.com>
Date: Tue, 18 Sep 2018 15:28:57 -0400
Subject: [PATCH] musicplus-le-changemusic 2.2 -> 2.1 backport

---
 src/p_setup.c | 36 ++++++++++++++++++++++----------
 src/p_spec.c  | 58 ++++++++++++++++++++++++++++++++++++++++++++-------
 2 files changed, 75 insertions(+), 19 deletions(-)

diff --git a/src/p_setup.c b/src/p_setup.c
index 6c6b9153..f504ffb5 100644
--- a/src/p_setup.c
+++ b/src/p_setup.c
@@ -1514,19 +1514,33 @@ static void P_LoadSideDefs2(lumpnum_t lumpnum)
 				{
 					M_Memcpy(process,msd->bottomtexture,8);
 					process[8] = '\0';
-					sd->bottomtexture = get_number(process)-1;
+					sd->bottomtexture = get_number(process);
 				}
-				M_Memcpy(process,msd->toptexture,8);
-				process[8] = '\0';
-				sd->text = Z_Malloc(7, PU_LEVEL, NULL);
 
-				// If they type in O_ or D_ and their music name, just shrug,
-				// then copy the rest instead.
-				if ((process[0] == 'O' || process[0] == 'D') && process[7])
-					M_Memcpy(sd->text, process+2, 6);
-				else // Assume it's a proper music name.
-					M_Memcpy(sd->text, process, 6);
-				sd->text[6] = 0;
+				if (!(msd->midtexture[0] == '-' && msd->midtexture[1] == '\0') || msd->midtexture[1] != '\0')
+				{
+					M_Memcpy(process,msd->midtexture,8);
+					process[8] = '\0';
+					sd->midtexture = get_number(process);
+				}
+
+				// always process if back sidedef, because we need that - symbol
+ 				sd->text = Z_Malloc(7, PU_LEVEL, NULL);
+				if (i == 1 || msd->toptexture[0] != '-' || msd->toptexture[1] != '\0')
+				{
+					M_Memcpy(process,msd->toptexture,8);
+					process[8] = '\0';
+
+					// If they type in O_ or D_ and their music name, just shrug,
+					// then copy the rest instead.
+					if ((process[0] == 'O' || process[0] == 'D') && process[7])
+						M_Memcpy(sd->text, process+2, 6);
+					else // Assume it's a proper music name.
+						M_Memcpy(sd->text, process, 6);
+					sd->text[6] = 0;
+				}
+				else
+					sd->text[0] = 0;
 				break;
 			}
 			case 414: // Play SFX
diff --git a/src/p_spec.c b/src/p_spec.c
index afc3c053..7832ff03 100644
--- a/src/p_spec.c
+++ b/src/p_spec.c
@@ -2419,18 +2419,60 @@ static void P_ProcessLineSpecial(line_t *line, mobj_t *mo, sector_t *callsec)
 			// console player only unless NOCLIMB is set
 			if ((line->flags & ML_NOCLIMB) || (mo && mo->player && P_IsLocalPlayer(mo->player)))
 			{
-				UINT16 tracknum = (UINT16)sides[line->sidenum[0]].bottomtexture;
+				boolean musicsame = (!sides[line->sidenum[0]].text[0] || !strnicmp(sides[line->sidenum[0]].text, S_MusicName(), 7));
+				UINT16 tracknum = (UINT16)max(sides[line->sidenum[0]].bottomtexture, 0);
+				INT32 position = (INT32)max(sides[line->sidenum[0]].midtexture, 0);
+				UINT32 prefadems = (UINT32)max(sides[line->sidenum[0]].textureoffset >> FRACBITS, 0);
+				UINT32 postfadems = (UINT32)max(sides[line->sidenum[0]].rowoffset >> FRACBITS, 0);
+				UINT8 fadetarget = (UINT8)max((line->sidenum[1] != 0xffff) ? sides[line->sidenum[1]].textureoffset >> FRACBITS : 0, 0);
+				INT16 fadesource = (INT16)max((line->sidenum[1] != 0xffff) ? sides[line->sidenum[1]].rowoffset >> FRACBITS : 0, -1);
 
-				strncpy(mapmusname, sides[line->sidenum[0]].text, 7);
-				mapmusname[6] = 0;
+				if (line->flags & ML_EFFECT1)
+				{
+					// adjust for loop point if subtracting
+					if (position < 0 && S_GetMusicLength() &&
+						S_GetMusicPosition() > S_GetMusicLoopPoint() &&
+						S_GetMusicPosition() + position < S_GetMusicLoopPoint())
+						position = max(S_GetMusicLength() - (S_GetMusicLoopPoint() - (S_GetMusicPosition() + position)), 0);
+					else
+						position = max(S_GetMusicPosition() + position, 0);
+				}
 
-				mapmusflags = tracknum & MUSIC_TRACKMASK;
-				if (!(line->flags & ML_BLOCKMONSTERS))
-					mapmusflags |= MUSIC_RELOADRESET;
+				if ((line->flags & ML_EFFECT2) && fadetarget && musicsame)
+				{
+					if (!postfadems)
+						S_SetInternalMusicVolume(fadetarget);
+					else
+						S_FadeMusicFromVolume(fadetarget, fadesource, postfadems);
 
-				mapmusposition = 0;
+					if (position)
+						S_SetMusicPosition(position);
+				}
+				else
+				{
+					strncpy(mapmusname, sides[line->sidenum[0]].text, 7);
+					mapmusname[6] = 0;
 
-				S_ChangeMusic(mapmusname, mapmusflags, !(line->flags & ML_EFFECT4));
+					mapmusflags = tracknum & MUSIC_TRACKMASK;
+					if (!(line->flags & ML_BLOCKMONSTERS))
+						mapmusflags |= MUSIC_RELOADRESET;
+					if (line->flags & ML_BOUNCY)
+						mapmusflags |= MUSIC_FORCERESET;
+
+					mapmusposition = position;
+
+					S_ChangeMusicEx(mapmusname, mapmusflags, !(line->flags & ML_EFFECT4), position,
+						!(line->flags & ML_EFFECT2) ? prefadems : 0,
+						!(line->flags & ML_EFFECT2) ? postfadems : 0);
+
+					if ((line->flags & ML_EFFECT2) && fadetarget)
+					{
+						if (!postfadems)
+							S_SetInternalMusicVolume(fadetarget);
+						else
+							S_FadeMusicFromVolume(fadetarget, fadesource, postfadems);
+					}
+				}
 
 				// Except, you can use the ML_BLOCKMONSTERS flag to change this behavior.
 				// if (mapmusflags & MUSIC_RELOADRESET) then it will reset the music in G_PlayerReborn.