diff --git a/src/actor.h b/src/actor.h
index 862cf4087..8ff4b367a 100644
--- a/src/actor.h
+++ b/src/actor.h
@@ -407,9 +407,11 @@ enum ActorRenderFlag
 	RF_SPRITETYPEMASK	= 0x7000,	// ---Different sprite types, not all implemented
 	RF_FACESPRITE		= 0x0000,	// Face sprite
 	RF_WALLSPRITE		= 0x1000,	// Wall sprite
-	RF_FLOORSPRITE		= 0x2000,	// Floor sprite
+	RF_FLATSPRITE		= 0x2000,	// Flat sprite
 	RF_VOXELSPRITE		= 0x3000,	// Voxel object
 	RF_INVISIBLE		= 0x8000,	// Don't bother drawing this actor
+	RF_ROLLSPRITE		= 0x40000,	//[marrub]roll the sprite billboard
+	RF_DONTFLIP			= 0x80000,	// Don't flip it when viewed from behind.
 
 	RF_FORCEYBILLBOARD		= 0x10000,	// [BB] OpenGL only: draw with y axis billboard, i.e. anchored to the floor (overrides gl_billboard_mode setting)
 	RF_FORCEXYBILLBOARD		= 0x20000,	// [BB] OpenGL only: draw with xy axis billboard, i.e. unanchored (overrides gl_billboard_mode setting)
diff --git a/src/g_strife/a_strifestuff.cpp b/src/g_strife/a_strifestuff.cpp
index 8b5788d44..4e49121fa 100644
--- a/src/g_strife/a_strifestuff.cpp
+++ b/src/g_strife/a_strifestuff.cpp
@@ -317,7 +317,7 @@ DEFINE_ACTION_FUNCTION(AActor, A_CheckTerrain)
 			int anglespeed = tagManager.GetFirstSectorTag(sec) - 100;
 			double speed = (anglespeed % 10) / 16.;
 			DAngle an = (anglespeed / 10) * (360 / 8.);
-			self->VelFromAngle(an, speed);
+			self->Thrust(an, speed);
 		}
 	}
 	return 0;
diff --git a/src/thingdef/thingdef_codeptr.cpp b/src/thingdef/thingdef_codeptr.cpp
index 7a9ac1ce0..4f4d88779 100644
--- a/src/thingdef/thingdef_codeptr.cpp
+++ b/src/thingdef/thingdef_codeptr.cpp
@@ -7068,3 +7068,4 @@ DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_FaceMovementDirection)
 	}
 	ACTION_RETURN_BOOL(true);
 }
+
diff --git a/src/thingdef/thingdef_data.cpp b/src/thingdef/thingdef_data.cpp
index efb7be0c2..b9e6414ff 100644
--- a/src/thingdef/thingdef_data.cpp
+++ b/src/thingdef/thingdef_data.cpp
@@ -265,6 +265,11 @@ static FFlagDef ActorFlagDefs[]=
 	DEFINE_FLAG(RF, INVISIBLE, AActor, renderflags),
 	DEFINE_FLAG(RF, FORCEYBILLBOARD, AActor, renderflags),
 	DEFINE_FLAG(RF, FORCEXYBILLBOARD, AActor, renderflags),
+	DEFINE_FLAG(RF, ROLLSPRITE, AActor, renderflags), // [marrub] roll the sprite billboard 
+			// [fgsfds] Flat sprites
+	DEFINE_FLAG(RF, FLATSPRITE, AActor, renderflags),
+	DEFINE_FLAG(RF, WALLSPRITE, AActor, renderflags),
+	DEFINE_FLAG(RF, DONTFLIP, AActor, renderflags),
 
 	// Bounce flags
 	DEFINE_FLAG2(BOUNCE_Walls, BOUNCEONWALLS, AActor, BounceFlags),
diff --git a/wadsrc/static/actors/actor.txt b/wadsrc/static/actors/actor.txt
index a531838d0..901d7a553 100644
--- a/wadsrc/static/actors/actor.txt
+++ b/wadsrc/static/actors/actor.txt
@@ -34,8 +34,7 @@ ACTOR Actor native //: Thinker
 	DefThreshold 100
 	BloodType "Blood", "BloodSplatter", "AxeBlood"
 	ExplosionDamage 128
-	MissileHeight 32
-	
+	MissileHeight 32	
 
 	// Functions
 	native bool CheckClass(class<Actor> checkclass, int ptr_select = AAPTR_DEFAULT, bool match_superclass = false);