diff --git a/src/gl/scene/gl_walls.cpp b/src/gl/scene/gl_walls.cpp
index db16a941a..30e10b73f 100644
--- a/src/gl/scene/gl_walls.cpp
+++ b/src/gl/scene/gl_walls.cpp
@@ -1654,7 +1654,10 @@ void GLWall::Process(seg_t *seg, sector_t * frontsector, sector_t * backsector)
 
 
 		/* mid texture */
-		bool drawfogboundary = gl_CheckFog(frontsector, backsector);
+		bool isportal = seg->linedef->isVisualPortal() && seg->sidedef == seg->linedef->sidedef[0];
+		sector_t *backsec = isportal? seg->linedef->getPortalDestination()->frontsector : backsector;
+
+		bool drawfogboundary = gl_CheckFog(frontsector, backsec);
 		FTexture *tex = TexMan(seg->sidedef->GetTexture(side_t::mid));
 		if (tex != NULL)
 		{
@@ -1672,7 +1675,7 @@ void GLWall::Process(seg_t *seg, sector_t * frontsector, sector_t * backsector)
 				fch1, fch2, ffh1, ffh2, bch1, bch2, bfh1, bfh2);
 		}
 
-		if (seg->linedef->isVisualPortal() && seg->sidedef == seg->linedef->sidedef[0])
+		if (isportal)
 		{
 			lineportal = linePortalToGL[seg->linedef->portalindex];
 			ztop[0] = bch1;
diff --git a/src/p_enemy.cpp b/src/p_enemy.cpp
index da4e3cc45..4b99a5f52 100644
--- a/src/p_enemy.cpp
+++ b/src/p_enemy.cpp
@@ -3061,7 +3061,7 @@ void A_Face(AActor *self, AActor *other, DAngle max_turn, DAngle max_pitch, DAng
 		double dist_z = target_z - source_z;
 		double ddist = g_sqrt(dist.X*dist.X + dist.Y*dist.Y + dist_z*dist_z);
 
-		DAngle other_pitch = DAngle::ToDegrees(g_asin(dist_z / ddist)).Normalized180();
+		DAngle other_pitch = -DAngle::ToDegrees(g_asin(dist_z / ddist)).Normalized180();
 		
 		if (max_pitch != 0)
 		{
diff --git a/src/p_pspr.cpp b/src/p_pspr.cpp
index 2bd3696d4..3ef74da73 100644
--- a/src/p_pspr.cpp
+++ b/src/p_pspr.cpp
@@ -390,13 +390,14 @@ void DPSprite::SetState(FState *newstate, bool pending)
 
 		if (ID != PSP_FLASH)
 		{ // It's still possible to set the flash layer's offsets with the action function.
+			// Anything going through here cannot be reliably interpolated so this has to reset the interpolation coordinates if it changes the values.
 			if (newstate->GetMisc1())
 			{ // Set coordinates.
-				x = newstate->GetMisc1();
+				oldx = x = newstate->GetMisc1();
 			}
 			if (newstate->GetMisc2())
 			{
-				y = newstate->GetMisc2();
+				oldy = y = newstate->GetMisc2();
 			}
 		}
 
@@ -1041,6 +1042,7 @@ enum WOFFlags
 	WOF_KEEPX =		1,
 	WOF_KEEPY =		1 << 1,
 	WOF_ADD =		1 << 2,
+	WOF_INTERPOLATE = 1 << 3,
 };
 
 void A_OverlayOffset(AActor *self, int layer, double wx, double wy, int flags)
@@ -1069,6 +1071,7 @@ void A_OverlayOffset(AActor *self, int layer, double wx, double wy, int flags)
 			else
 			{
 				psp->x = wx;
+				if (!(flags & WOF_INTERPOLATE)) psp->oldx = psp->x;
 			}
 		}
 		if (!(flags & WOF_KEEPY))
@@ -1080,6 +1083,7 @@ void A_OverlayOffset(AActor *self, int layer, double wx, double wy, int flags)
 			else
 			{
 				psp->y = wy;
+				if (!(flags & WOF_INTERPOLATE)) psp->oldy = psp->y;
 			}
 		}
 	}
diff --git a/src/r_data/sprites.cpp b/src/r_data/sprites.cpp
index 80c2d9488..3e0cb80cc 100644
--- a/src/r_data/sprites.cpp
+++ b/src/r_data/sprites.cpp
@@ -26,10 +26,8 @@ DWORD			NumStdSprites;		// The first x sprites that don't belong to skins.
 struct spriteframewithrotate : public spriteframe_t
 {
 	int rotate;
-}
-sprtemp[MAX_SPRITE_FRAMES];
-int 			maxframe;
-char*			spritename;
+};
+
 
 // [RH] skin globals
 FPlayerSkin		*skins;
@@ -46,7 +44,7 @@ PalEntry		OtherGameSkinPalette[256];
 // [RH] Removed checks for coexistance of rotation 0 with other
 //		rotations and made it look more like BOOM's version.
 //
-static bool R_InstallSpriteLump (FTextureID lump, unsigned frame, char rot, bool flipped)
+static bool R_InstallSpriteLump (FTextureID lump, unsigned frame, char rot, bool flipped, spriteframewithrotate *sprtemp, int &maxframe)
 {
 	unsigned rotation;
 
@@ -119,7 +117,7 @@ static bool R_InstallSpriteLump (FTextureID lump, unsigned frame, char rot, bool
 
 
 // [RH] Seperated out of R_InitSpriteDefs()
-static void R_InstallSprite (int num)
+static void R_InstallSprite (int num, spriteframewithrotate *sprtemp, int &maxframe)
 {
 	int frame;
 	int framestart;
@@ -267,6 +265,8 @@ void R_InitSpriteDefs ()
 	unsigned int i, j, smax, vmax;
 	DWORD intname;
 
+	spriteframewithrotate sprtemp[MAX_SPRITE_FRAMES];
+
 	// Create a hash table to speed up the process
 	smax = TexMan.NumTextures();
 	hashes = new Hasher[smax];
@@ -348,7 +348,7 @@ void R_InitSpriteDefs ()
 			sprtemp[j].Voxel = NULL;
 		}
 				
-		maxframe = -1;
+		int maxframe = -1;
 		intname = sprites[i].dwName;
 
 		// scan the lumps, filling in the frames for whatever is found
@@ -358,10 +358,10 @@ void R_InitSpriteDefs ()
 			FTexture *tex = TexMan[hash];
 			if (TEX_DWNAME(tex) == intname)
 			{
-				bool res = R_InstallSpriteLump (FTextureID(hash), tex->Name[4] - 'A', tex->Name[5], false);
+				bool res = R_InstallSpriteLump (FTextureID(hash), tex->Name[4] - 'A', tex->Name[5], false, sprtemp, maxframe);
 
 				if (tex->Name[6] && res)
-					R_InstallSpriteLump (FTextureID(hash), tex->Name[6] - 'A', tex->Name[7], true);
+					R_InstallSpriteLump (FTextureID(hash), tex->Name[6] - 'A', tex->Name[7], true, sprtemp, maxframe);
 			}
 			hash = hashes[hash].Next;
 		}
@@ -398,7 +398,7 @@ void R_InitSpriteDefs ()
 			hash = vh->Next;
 		}
 		
-		R_InstallSprite ((int)i);
+		R_InstallSprite ((int)i, sprtemp, maxframe);
 	}
 
 	delete[] hashes;
@@ -762,13 +762,14 @@ void R_InitSkins (void)
 
 			for(int spr = 0; spr<2; spr++)
 			{
+				spriteframewithrotate sprtemp[MAX_SPRITE_FRAMES];
 				memset (sprtemp, 0xFFFF, sizeof(sprtemp));
 				for (k = 0; k < MAX_SPRITE_FRAMES; ++k)
 				{
 					sprtemp[k].Flip = 0;
 					sprtemp[k].Voxel = NULL;
 				}
-				maxframe = -1;
+				int maxframe = -1;
 
 				if (spr == 1)
 				{
@@ -792,10 +793,10 @@ void R_InitSkins (void)
 					if (lnameint == intname)
 					{
 						FTextureID picnum = TexMan.CreateTexture(k, FTexture::TEX_SkinSprite);
-						bool res = R_InstallSpriteLump (picnum, lname[4] - 'A', lname[5], false);
+						bool res = R_InstallSpriteLump (picnum, lname[4] - 'A', lname[5], false, sprtemp, maxframe);
 
 						if (lname[6] && res)
-							R_InstallSpriteLump (picnum, lname[6] - 'A', lname[7], true);
+							R_InstallSpriteLump (picnum, lname[6] - 'A', lname[7], true, sprtemp, maxframe);
 					}
 				}
 
@@ -811,7 +812,7 @@ void R_InitSkins (void)
 				int sprno = (int)sprites.Push (temp);
 				if (spr==0)	skins[i].sprite = sprno;
 				else skins[i].crouchsprite = sprno;
-				R_InstallSprite (sprno);
+				R_InstallSprite (sprno, sprtemp, maxframe);
 			}
 		}
 
diff --git a/wadsrc/static/zscript/constants.txt b/wadsrc/static/zscript/constants.txt
index 147b23e4e..6597f8323 100644
--- a/wadsrc/static/zscript/constants.txt
+++ b/wadsrc/static/zscript/constants.txt
@@ -703,6 +703,7 @@ enum EWeaponOffsetFlags
 	WOF_KEEPX =		1,
 	WOF_KEEPY =		1 << 1,
 	WOF_ADD =		1 << 2,
+	WOF_INTERPOLATE = 1 << 3,
 };
 
 // Flags for psprite layers