- fixed: It was not possible to step through a ceiling portal into the upper sector.

src/p_checkposition.h

@@ -33,8 +33,9 @@ struct FCheckPosition
 	AActor			*stepthing;
 	// [RH] These are used by PIT_CheckThing and P_XYMovement to apply
 	// ripping damage once per tic instead of once per move.
-	bool			DoRipping;
 	TMap<AActor*, bool> LastRipped;
+	bool			DoRipping;
+	bool			portalstep;
 
 	int				PushTime;
 

src/p_map.cpp

@@ -728,6 +728,22 @@ bool PIT_CheckLine(FMultiBlockLinesIterator &mit, FMultiBlockLinesIterator::Chec
 			// Since a one-sided line does not have an opening there's nothing left to do about it.
 			return true;
 		}
+
+		// check if the actor can step through the ceiling portal. In this case one-sided lines in the current area should not block
+		if (!cres.line->frontsector->PortalBlocksMovement(sector_t::ceiling))
+		{
+			double portz = cres.line->frontsector->GetPortalPlaneZ(sector_t::ceiling);
+			if (tm.thing->Z() < portz && tm.thing->Z() + tm.thing->MaxStepHeight >= portz && tm.floorz < portz)
+			{
+				tm.floorz = portz;
+				tm.floorsector = cres.line->frontsector;
+				tm.floorpic = cres.line->sidedef[0]->GetTexture(side_t::mid);
+				tm.floorterrain = 0;
+				tm.portalstep = true;
+				return true;
+			}
+		}
+
 		if (tm.thing->flags2 & MF2_BLASTED)
 		{
 			P_DamageMobj(tm.thing, NULL, NULL, tm.thing->Mass >> 5, NAME_Melee);
@@ -1974,6 +1990,7 @@ bool P_TryMove(AActor *thing, const DVector2 &pos,
 	sector_t*	newsec;
 
 	tm.floatok = false;
+	tm.portalstep = false;
 	oldz = thing->Z();
 	if (onfloor)
 	{
@@ -2246,6 +2263,7 @@ bool P_TryMove(AActor *thing, const DVector2 &pos,
 				thing->LinkToWorld();
 				P_FindFloorCeiling(thing);
 				portalcrossed = true;
+				tm.portalstep = false;
 			}
 			else if (!portalcrossed)
 			{
@@ -2271,6 +2289,7 @@ bool P_TryMove(AActor *thing, const DVector2 &pos,
 				P_FindFloorCeiling(thing);
 				thing->ClearInterpolation();
 				portalcrossed = true;
+				tm.portalstep = false;
 			}
 			// if this is the current camera we need to store the point where the portal was crossed and the exit
 			// so that the renderer can properly calculate an interpolated position along the movement path.
@@ -2410,6 +2429,20 @@ bool P_TryMove(AActor *thing, const DVector2 &pos,
 		}
 	}
 
+	// If the actor stepped through a ceiling portal we need to reacquire the actual position info after the transition
+	if (tm.portalstep)
+	{
+		DVector3 oldpos = thing->Pos();
+		thing->UnlinkFromWorld();
+		thing->SetXYZ(thing->PosRelative(thing->Sector->GetOppositePortalGroup(sector_t::ceiling)));
+		thing->Prev = thing->Pos() - oldpos;
+		thing->Sector = P_PointInSector(thing->Pos());
+		thing->PrevPortalGroup = thing->Sector->PortalGroup;
+		thing->LinkToWorld();
+
+		P_FindFloorCeiling(thing);
+	}
+
 	// [RH] If changing sectors, trigger transitions
 	thing->CheckSectorTransition(oldsec);
 	thing->flags6 &= ~MF6_INTRYMOVE;

src/p_mobj.cpp

@@ -2117,21 +2117,23 @@ explode:
 			if (mo->Pos().XY() != ptry)
 			{
 				// If the new position does not match the desired position, the player
-				// must have gone through a teleporter, so stop moving right now if it
+				// must have gone through a teleporter or portal.
-				// was a regular teleporter. If it was a line-to-line or fogless teleporter,
+				
-				// the move should continue, but start and move need to change.
 				if (mo->Vel.X == 0 && mo->Vel.Y == 0)
 				{
+					// Stop moving right now if it was a regular teleporter.
 					step = steps;
 				}
 				else
 				{
+					// It was a portal, line-to-line or fogless teleporter, so the move should continue.
+					// For that we need to adjust the start point, and the movement vector.
 					DAngle anglediff = deltaangle(oldangle, mo->Angles.Yaw);
 
 					if (anglediff != 0)
 					{
 						move = move.Rotated(anglediff);
-						oldangle = mo->Angles.Yaw;	// in case more moves are needed this needs to be updated.
+						oldangle = mo->Angles.Yaw;
 					}
 					start = mo->Pos() - move * step / steps;
 				}
@@ -3225,7 +3227,7 @@ DVector3 AActor::GetPortalTransition(double byoffset, sector_t **pSec)
 
 	while (!sec->PortalBlocksMovement(sector_t::ceiling))
 	{
-		if (testz > sec->GetPortalPlaneZ(sector_t::ceiling))
+		if (testz >= sec->GetPortalPlaneZ(sector_t::ceiling))
 		{
 			pos = PosRelative(sec->GetOppositePortalGroup(sector_t::ceiling));
 			sec = P_PointInSector(pos);
@@ -3237,7 +3239,7 @@ DVector3 AActor::GetPortalTransition(double byoffset, sector_t **pSec)
 	{
 		while (!sec->PortalBlocksMovement(sector_t::floor))
 		{
-			if (testz <= sec->GetPortalPlaneZ(sector_t::floor))
+			if (testz < sec->GetPortalPlaneZ(sector_t::floor))
 			{
 				pos = PosRelative(sec->GetOppositePortalGroup(sector_t::floor));
 				sec = P_PointInSector(pos);
@@ -3256,7 +3258,7 @@ void AActor::CheckPortalTransition(bool islinked)
 	bool moved = false;
 	while (!Sector->PortalBlocksMovement(sector_t::ceiling))
 	{
-		if (Z() > Sector->GetPortalPlaneZ(sector_t::ceiling))
+		if (Z() >= Sector->GetPortalPlaneZ(sector_t::ceiling))
 		{
 			DVector3 oldpos = Pos();
 			if (islinked && !moved) UnlinkFromWorld();