From 583734861ed49d22ba7d147c1601070ccd8496a9 Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <coelckers@users.noreply.github.com>
Date: Sun, 12 Jan 2020 13:21:15 +0100
Subject: [PATCH] - compatibility workaround for using Scroll_Texture_Model
 with a line id of 0.

This would do very bad things if not being checked for.
---
 src/maploader/specials.cpp | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/src/maploader/specials.cpp b/src/maploader/specials.cpp
index b30baba49..64f3ea7b8 100644
--- a/src/maploader/specials.cpp
+++ b/src/maploader/specials.cpp
@@ -1325,11 +1325,18 @@ void MapLoader::SpawnScrollers()
 			// (same direction and speed as scrolling floors)
 		case Scroll_Texture_Model:
 		{
-			auto itr = Level->GetLineIdIterator(l->args[0]);
-			while ((s = itr.Next()) >= 0)
+			if (l->args[0] != 0)
 			{
-				if (s != (int)i)
-					Level->CreateThinker<DScroller>(dx, dy, &Level->lines[s], control, accel);
+				auto itr = Level->GetLineIdIterator(l->args[0]);
+				while ((s = itr.Next()) >= 0)
+				{
+					if (s != (int)i)
+						Level->CreateThinker<DScroller>(dx, dy, &Level->lines[s], control, accel);
+				}
+			}
+			else
+			{
+				Level->CreateThinker<DScroller>(dx, dy, l, control, accel);
 			}
 			break;
 		}