From 7fd7cad52c2e6e29da01a147d261c977deb57810 Mon Sep 17 00:00:00 2001
From: NepDisk <nepdisk@noreply.codeberg.org>
Date: Mon, 22 Dec 2025 14:14:40 -0500
Subject: [PATCH] Fix usage of 502 in v1 kart maps

---
 src/p_setup.c |  6 ++++++
 src/p_spec.c  | 28 ++++++++++++++++++++++++----
 2 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/src/p_setup.c b/src/p_setup.c
index 34b4f344b..3b2392ffd 100644
--- a/src/p_setup.c
+++ b/src/p_setup.c
@@ -6647,6 +6647,12 @@ static void P_ConvertBinaryLinedefTypes(void)
 				lines[i].args[2] = lines[i].dx >> FRACBITS;
 				lines[i].args[3] = lines[i].dy >> FRACBITS;
 			}
+
+			if (mapnamespace == MNS_SRB2KART && lines[i].special == 502)
+				lines[i].args[5] = 1;
+			else
+				lines[i].args[5] = 0;
+
 			lines[i].args[4] = lines[i].special - 502;
 			lines[i].special = 502;
 			break;
diff --git a/src/p_spec.c b/src/p_spec.c
index 10b44223a..39fd9b935 100644
--- a/src/p_spec.c
+++ b/src/p_spec.c
@@ -8512,6 +8512,18 @@ static void P_SpawnPlaneScroller(line_t *l, fixed_t dx, fixed_t dy, INT32 contro
 	}
 }
 
+// Only used for compat with kart v1 maps....
+static void Add_WallScroller(fixed_t dx, fixed_t dy, const line_t *l, INT32 control, INT32 accel)
+{
+	fixed_t x = abs(l->dx), y = abs(l->dy), d;
+	if (y > x)
+		d = x, x = y, y = d;
+	d = FixedDiv(x, FINESINE((tantoangle[FixedDiv(y, x) >> DBITS] + ANGLE_90) >> ANGLETOFINESHIFT));
+	x = -FixedDiv(FixedMul(dy, l->dy) + FixedMul(dx, l->dx), d);
+	y = -FixedDiv(FixedMul(dx, l->dy) - FixedMul(dy, l->dx), d);
+	Add_Scroller(sc_side, x, y, control, *l->sidenum, accel, 0);
+}
+
 /** Initializes the scrollers.
   *
   * \todo Get rid of all the magic numbers.
@@ -8566,10 +8578,18 @@ static void P_SpawnScrollers(void)
 				TAG_ITER_LINES(l->args[0], s)
 					if (s != (INT32)i)
 					{
-						if (l->args[1] != TMSD_BACK)
-							Add_Scroller(sc_side, l->args[2] << (FRACBITS - SCROLL_SHIFT), l->args[3] << (FRACBITS - SCROLL_SHIFT), control, lines[s].sidenum[0], accel, 0);
-						if (l->args[1] != TMSD_FRONT && lines[s].sidenum[1] != 0xffff)
-							Add_Scroller(sc_side, l->args[2] << (FRACBITS - SCROLL_SHIFT), l->args[3] << (FRACBITS - SCROLL_SHIFT), control, lines[s].sidenum[1], accel, 0);
+						if (l->args[5] == 1)
+						{
+							// Legacy v1 support....
+							Add_WallScroller(l->args[2] << (FRACBITS - SCROLL_SHIFT), l->args[3] << (FRACBITS - SCROLL_SHIFT), lines+s, control, accel);
+						}
+						else
+						{
+							if (l->args[1] != TMSD_BACK)
+								Add_Scroller(sc_side, l->args[2] << (FRACBITS - SCROLL_SHIFT), l->args[3] << (FRACBITS - SCROLL_SHIFT), control, lines[s].sidenum[0], accel, 0);
+							if (l->args[1] != TMSD_FRONT && lines[s].sidenum[1] != 0xffff)
+								Add_Scroller(sc_side, l->args[2] << (FRACBITS - SCROLL_SHIFT), l->args[3] << (FRACBITS - SCROLL_SHIFT), control, lines[s].sidenum[1], accel, 0);
+						}
 					}
 				break;
 			}