As requested by Nev3r and VAda, seperating MF_PAPER into FF_PAPERSPRITE and MF_PAPERCOLLISION.

src/dehacked.c

@@ -7045,6 +7045,7 @@ struct {
 
 	// Frame settings
 	{"FF_FRAMEMASK",FF_FRAMEMASK},
+	{"FF_PAPERSPRITE",FF_PAPERSPRITE},
 	{"FF_ANIMATE",FF_ANIMATE},
 	{"FF_FULLBRIGHT",FF_FULLBRIGHT},
 	{"FF_TRANSMASK",FF_TRANSMASK},

src/doomdef.h

@@ -498,7 +498,7 @@ extern const char *compdate, *comptime, *comprevision, *compbranch;
 /// \note	You should leave this enabled unless you're working with a future SRB2 version.
 #define MUSICSLOT_COMPATIBILITY
 
-/// Experimental attempts at preventing MF_PAPER objects from getting stuck in walls.
+/// Experimental attempts at preventing MF_PAPERCOLLISION objects from getting stuck in walls.
 //#define PAPER_COLLISIONCORRECTION
 
 #endif // __DOOMDEF__

src/p_map.c

@@ -498,7 +498,7 @@ static boolean PIT_CheckThing(mobj_t *thing)
 	if (abs(thing->x - tmx) >= blockdist || abs(thing->y - tmy) >= blockdist)
 		return true; // didn't hit it
 
-	if (thing->flags & MF_PAPER) // CAUTION! Very easy to get stuck inside MF_SOLID objects. Giving the player MF_PAPER is a bad idea unless you know what you're doing.
+	if (thing->flags & MF_PAPERCOLLISION) // CAUTION! Very easy to get stuck inside MF_SOLID objects. Giving the player MF_PAPERCOLLISION is a bad idea unless you know what you're doing.
 	{
 		fixed_t cosradius, sinradius;
 		vertex_t v1, v2; // fake vertexes
@@ -517,7 +517,7 @@ static boolean PIT_CheckThing(mobj_t *thing)
 		junk.dx = v2.x - v1.x;
 		junk.dy = v2.y - v1.y;
 
-		if (tmthing->flags & MF_PAPER) // more strenuous checking to prevent clipping issues
+		if (tmthing->flags & MF_PAPERCOLLISION) // more strenuous checking to prevent clipping issues
 		{
 			INT32 check1, check2, check3, check4;
 			cosradius = FixedMul(tmthing->radius, FINECOSINE(tmthing->angle>>ANGLETOFINESHIFT));
@@ -538,7 +538,7 @@ static boolean PIT_CheckThing(mobj_t *thing)
 				return true; // the line doesn't cross between either pair of opposite corners
 		}
 	}
-	else if (tmthing->flags & MF_PAPER)
+	else if (tmthing->flags & MF_PAPERCOLLISION)
 	{
 		fixed_t cosradius, sinradius;
 		vertex_t v1, v2; // fake vertexes
@@ -557,7 +557,7 @@ static boolean PIT_CheckThing(mobj_t *thing)
 		junk.dx = v2.x - v1.x;
 		junk.dy = v2.y - v1.y;
 
-		// no need to check whether thing has MF_PAPER, since checked above
+		// no need to check whether thing has MF_PAPERCOLLISION, since checked above
 
 		if ((P_PointOnLineSide(thing->x - thing->radius, thing->y - thing->radius, &junk)
 		== P_PointOnLineSide(thing->x + thing->radius, thing->y + thing->radius, &junk))
@@ -1230,7 +1230,7 @@ static boolean PIT_CheckLine(line_t *ld)
 	if (P_BoxOnLineSide(tmbbox, ld) != -1)
 		return true;
 
-	if (tmthing->flags & MF_PAPER) // Caution! Turning whilst up against a wall will get you stuck. You probably shouldn't give the player this flag.
+	if (tmthing->flags & MF_PAPERCOLLISION) // Caution! Turning whilst up against a wall will get you stuck. You probably shouldn't give the player this flag.
 	{
 		fixed_t cosradius, sinradius;
 		cosradius = FixedMul(tmthing->radius, FINECOSINE(tmthing->angle>>ANGLETOFINESHIFT));

src/p_mobj.h

@@ -107,8 +107,8 @@ typedef enum
 	MF_NOSECTOR         = 1<<3,
 	// Don't use the blocklinks (inert but displayable)
 	MF_NOBLOCKMAP       = 1<<4,
-	// Paper-thin. Drawn like a midtexture, has a flat collision bound.
-	MF_PAPER            = 1<<5,
+	// Thin, paper-like collision bound (for visual equivalent, see FF_PAPERSPRITE)
+	MF_PAPERCOLLISION            = 1<<5,
 	// You can push this object. It can activate switches and things by pushing it on top.
 	MF_PUSHABLE         = 1<<6,
 	// Object is a boss.

src/p_pspr.h

@@ -36,7 +36,9 @@
 #endif
 
 /// \brief Frame flags: only the frame number
-#define FF_FRAMEMASK 0x3fff
+#define FF_FRAMEMASK 0x1ff
+/// \brief Frame flags: Thin, paper-like sprite (for collision equivalent, see MF_PAPERCOLLISION)
+#define FF_PAPERSPRITE 0x800
 /// \brief Frame flags: Simple stateless animation
 #define FF_ANIMATE 0x4000
 /// \brief Frame flags: frame always appears full bright

src/r_things.c

@@ -1123,7 +1123,7 @@ static void R_ProjectSprite(mobj_t *thing)
 	fixed_t iscale;
 	fixed_t scalestep; // toast '16
 	fixed_t offset, offset2;
-	boolean flatsprite = (thing->flags & MF_PAPER);
+	boolean papersprite = (thing->frame & FF_PAPERSPRITE);
 
 	//SoM: 3/17/2000
 	fixed_t gz, gzt;
@@ -1143,7 +1143,7 @@ static void R_ProjectSprite(mobj_t *thing)
 	tz = gxt-gyt;
 
 	// thing is behind view plane?
-	if (!(flatsprite) && (tz < FixedMul(MINZ, this_scale))) // flatsprite clipping is handled later
+	if (!(papersprite) && (tz < FixedMul(MINZ, this_scale))) // papersprite clipping is handled later
 		return;
 
 	gxt = -FixedMul(tr_x, viewsin);
@@ -1203,10 +1203,10 @@ static void R_ProjectSprite(mobj_t *thing)
 		I_Error("R_ProjectSprite: sprframes NULL for sprite %d\n", thing->sprite);
 #endif
 
-	if (sprframe->rotate != SRF_SINGLE || flatsprite)
+	if (sprframe->rotate != SRF_SINGLE || papersprite)
 	{
 		ang = R_PointToAngle (thing->x, thing->y) - thing->angle;
-		if (flatsprite)
+		if (papersprite)
 			ang_scale = abs(FINESINE(ang>>ANGLETOFINESHIFT));
 	}
 
@@ -1260,7 +1260,7 @@ static void R_ProjectSprite(mobj_t *thing)
 	if (x2 < 0)
 		return;
 
-	if (flatsprite)
+	if (papersprite)
 	{
 		fixed_t yscale2, cosmul, sinmul, tz2;
 		INT32 range;
@@ -1290,7 +1290,7 @@ static void R_ProjectSprite(mobj_t *thing)
 		yscale2 = FixedDiv(projectiony, tz2);
 		if (yscale2 < 64) return; // ditto
 
-		if (max(tz, tz2) < FixedMul(MINZ, this_scale)) // non-flatsprite clipping is handled earlier
+		if (max(tz, tz2) < FixedMul(MINZ, this_scale)) // non-papersprite clipping is handled earlier
 			return;
 
 		if (x2 > x1)