From db8c3d606ed23dfb6b2408c4ddbf0af91d33f3de Mon Sep 17 00:00:00 2001
From: kraflab <kraflab@gmail.com>
Date: Fri, 23 Apr 2021 16:22:27 +0200
Subject: [PATCH] Track scrolling for ledgeblock

---
 prboom2/src/p_map.c  | 7 +++++--
 prboom2/src/p_mobj.c | 1 +
 prboom2/src/p_mobj.h | 1 +
 prboom2/src/p_spec.c | 3 +++
 4 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/prboom2/src/p_map.c b/prboom2/src/p_map.c
index 0b241dc2e..4a28f3427 100644
--- a/prboom2/src/p_map.c
+++ b/prboom2/src/p_map.c
@@ -1021,7 +1021,10 @@ dboolean P_TryMove(mobj_t* thing,fixed_t x,fixed_t y,
      */
     if (!(thing->flags & (MF_DROPOFF|MF_FLOAT)))
     {
-      if (comp[comp_dropoff] || comp[comp_ledgeblock])
+      dboolean ledgeblock = comp[comp_ledgeblock] &&
+                            !(mbf21 && thing->intflags & MIF_SCROLLING);
+
+      if (comp[comp_dropoff] || ledgeblock)
       {
         // e6y
         // Fix demosync bug in mbf compatibility mode
@@ -1033,7 +1036,7 @@ dboolean P_TryMove(mobj_t* thing,fixed_t x,fixed_t y,
         // http://www.doomworld.com/idgames/index.php?id=11138
         if (
           (
-            comp[comp_ledgeblock] ||
+            ledgeblock ||
             !dropoff ||
             (
               !prboom_comp[PC_NO_DROPOFF].state &&
diff --git a/prboom2/src/p_mobj.c b/prboom2/src/p_mobj.c
index f116dcf8e..ff07aa064 100644
--- a/prboom2/src/p_mobj.c
+++ b/prboom2/src/p_mobj.c
@@ -993,6 +993,7 @@ void P_MobjThinker (mobj_t* mobj)
   if (mobj->momx | mobj->momy || mobj->flags & MF_SKULLFLY)
   {
     P_XYMovement(mobj);
+    mobj->intflags &= ~MIF_SCROLLING;
     if (mobj->thinker.function != P_MobjThinker) // cph - Must've been removed
       return;       // killough - mobj was removed
   }
diff --git a/prboom2/src/p_mobj.h b/prboom2/src/p_mobj.h
index de3df8435..b52ac551f 100644
--- a/prboom2/src/p_mobj.h
+++ b/prboom2/src/p_mobj.h
@@ -238,6 +238,7 @@
 enum {
   MIF_FALLING = 1,      // Object is falling
   MIF_ARMED = 2,        // Object is armed (for MF_TOUCHY objects)
+  MIF_SCROLLING = 4,    // Object is affected by scroller / pusher / puller
 };
 
 // heretic
diff --git a/prboom2/src/p_spec.c b/prboom2/src/p_spec.c
index 363e28325..dbdb8a927 100644
--- a/prboom2/src/p_spec.c
+++ b/prboom2/src/p_spec.c
@@ -2938,6 +2938,7 @@ void T_Scroll(scroll_t *s)
             // non-floating, and clipped.
             thing->momx += dx;
             thing->momy += dy;
+            thing->intflags |= MIF_SCROLLING;
           }
       break;
 
@@ -3446,6 +3447,7 @@ static dboolean PIT_PushThing(mobj_t* thing)
           pushangle >>= ANGLETOFINESHIFT;
           thing->momx += FixedMul(speed,finecosine[pushangle]);
           thing->momy += FixedMul(speed,finesine[pushangle]);
+          thing->intflags |= MIF_SCROLLING;
         }
     }
   return true;
@@ -3575,6 +3577,7 @@ void T_Pusher(pusher_t *p)
             }
         thing->momx += xspeed<<(FRACBITS-PUSH_FACTOR);
         thing->momy += yspeed<<(FRACBITS-PUSH_FACTOR);
+        thing->intflags |= MIF_SCROLLING;
         }
 }