Added A_SpriteOffset. (#895)

- Coordinates work akin to A_OverlayOffset: +X shifts to the right, +Y shifts down.

src/playsim/actor.h

@@ -995,6 +995,7 @@ public:
 
 	DVector3		OldRenderPos;
 	DVector3		Vel;
+	DVector2		SpriteOffset;
 	double			Speed;
 	double			FloatSpeed;
 

src/playsim/p_mobj.cpp

@@ -365,6 +365,7 @@ void AActor::Serialize(FSerializer &arc)
 		A("spawntime", SpawnTime)
 		A("spawnorder", SpawnOrder)
 		A("friction", Friction)
+		A("SpriteOffset", SpriteOffset)
 		A("userlights", UserLights);
 
 		SerializeTerrain(arc, "floorterrain", floorterrain, &def->floorterrain);

src/rendering/hwrenderer/scene/hw_sprites.cpp

@@ -899,11 +899,10 @@ void HWSprite::Process(HWDrawInfo *di, AActor* thing, sector_t * sector, area_t
 
 		r.Scale(sprscale.X, sprscale.Y);
 		
-		float rightfac = -r.left;
+		float SpriteOffY = thing->SpriteOffset.Y;
+		float rightfac = -r.left - thing->SpriteOffset.X;
 		float leftfac = rightfac - r.width;
-		float bottomfac = -r.top;
-		float topfac = bottomfac - r.height;
-		z1 = z - r.top;
+		z1 = z - r.top - SpriteOffY;
 		z2 = z1 - r.height;
 
 		float spriteheight = sprscale.Y * r.height;
@@ -914,31 +913,39 @@ void HWSprite::Process(HWDrawInfo *di, AActor* thing, sector_t * sector, area_t
 			PerformSpriteClipAdjustment(thing, thingpos, spriteheight);
 		}
 
-		float viewvecX;
-		float viewvecY;
 		switch (spritetype)
 		{
 		case RF_FACESPRITE:
-			viewvecX = vp.ViewVector.X;
-			viewvecY = vp.ViewVector.Y;
+		{
+			float viewvecX = vp.ViewVector.X;
+			float viewvecY = vp.ViewVector.Y;
 
 			x1 = x - viewvecY*leftfac;
 			x2 = x - viewvecY*rightfac;
 			y1 = y + viewvecX*leftfac;
 			y2 = y + viewvecX*rightfac;
 			break;
-
+		}
 		case RF_FLATSPRITE:
 		{
+			float bottomfac = -r.top - SpriteOffY;
+			float topfac = bottomfac - r.height;
+
 			x1 = x + leftfac;
 			x2 = x + rightfac;
 			y1 = y - topfac;
 			y2 = y - bottomfac;
+			// [MC] Counteract in case of any potential problems. Tests so far haven't
+			// shown any outstanding issues but that doesn't mean they won't appear later
+			// when more features are added.
+			z1 += SpriteOffY;
+			z2 += SpriteOffY;
+			break;
 		}
-		break;
 		case RF_WALLSPRITE:
-			viewvecX = Angles.Yaw.Cos();
-			viewvecY = Angles.Yaw.Sin();
+		{
+			float viewvecX = Angles.Yaw.Cos();
+			float viewvecY = Angles.Yaw.Sin();
 
 			x1 = x + viewvecY*leftfac;
 			x2 = x + viewvecY*rightfac;
@@ -946,6 +953,7 @@ void HWSprite::Process(HWDrawInfo *di, AActor* thing, sector_t * sector, area_t
 			y2 = y - viewvecX*rightfac;
 			break;
 		}
+		}
 	}
 	else
 	{

src/rendering/swrenderer/scene/r_opaque_pass.cpp

@@ -1004,9 +1004,9 @@ namespace swrenderer
 
 	bool RenderOpaquePass::GetThingSprite(AActor *thing, ThingSprite &sprite)
 	{
+		// The X offsetting (SpriteOffset.X) is performed in r_sprite.cpp, in RenderSprite::Project().
 		sprite.pos = thing->InterpolatedPosition(Thread->Viewport->viewpoint.TicFrac);
-		sprite.pos.Z += thing->GetBobOffset(Thread->Viewport->viewpoint.TicFrac);
-
+		sprite.pos.Z += thing->GetBobOffset(Thread->Viewport->viewpoint.TicFrac) - thing->SpriteOffset.Y;
 		sprite.spritenum = thing->sprite;
 		sprite.tex = nullptr;
 		sprite.voxel = nullptr;

src/rendering/swrenderer/things/r_sprite.cpp

@@ -81,8 +81,11 @@ namespace swrenderer
 		const double thingxscalemul = spriteScale.X / tex->GetScale().X;
 
 		// Calculate billboard line for the sprite
+		double SpriteOffX = (thing) ? thing->SpriteOffset.X : 0.;
 		DVector2 dir = { viewport->viewpoint.Sin, -viewport->viewpoint.Cos };
-		DVector2 pt1 = pos.XY() - viewport->viewpoint.Pos.XY() - dir * (((renderflags & RF_XFLIP) ? (tex->GetWidth() - tex->GetLeftOffsetSW() - 1) : tex->GetLeftOffsetSW()) * thingxscalemul);
+		DVector2 trs = pos.XY() - viewport->viewpoint.Pos.XY();
+		trs = { trs.X + SpriteOffX * dir.X, trs.Y + SpriteOffX * dir.Y };
+		DVector2 pt1 = trs - dir * (((renderflags & RF_XFLIP) ? (tex->GetWidth() - tex->GetLeftOffsetSW() - 1) : tex->GetLeftOffsetSW()) * thingxscalemul);
 		DVector2 pt2 = pt1 + dir * (tex->GetWidth() * thingxscalemul);
 
 		FWallCoords wallc;

src/scripting/vmthunks_actors.cpp

@@ -1775,6 +1775,7 @@ DEFINE_FIELD_NAMED(AActor, __Pos, pos)
 DEFINE_FIELD_NAMED(AActor, __Pos.X, x)
 DEFINE_FIELD_NAMED(AActor, __Pos.Y, y)
 DEFINE_FIELD_NAMED(AActor, __Pos.Z, z)
+DEFINE_FIELD(AActor, SpriteOffset)
 DEFINE_FIELD(AActor, Prev)
 DEFINE_FIELD(AActor, SpriteAngle)
 DEFINE_FIELD(AActor, SpriteRotation)

wadsrc/static/zscript/actors/actions.zs

@@ -95,4 +95,9 @@ extend class Actor
 		}
 	}
 
+	void A_SpriteOffset(double ox = 0.0, double oy = 0.0)
+	{
+		SpriteOffset.X = ox;
+		SpriteOffset.Y = oy;
+	}
 }

wadsrc/static/zscript/actors/actor.zs

@@ -89,6 +89,7 @@ class Actor : Thinker native
 	native PlayerInfo Player;
 	native readonly vector3 Pos;
 	native vector3 Prev;
+	native vector2 SpriteOffset;
 	native double spriteAngle;
 	native double spriteRotation;
 	native double VisibleStartAngle;