Fix dancing sprites due to texture coordinate calculations not taking pixel centers into account

Merge R_DrawMaskedColumn and R_DrawMaskedColumnHoriz into one function to remove code duplication

src/r_draw.h

@@ -116,7 +116,6 @@ extern void (*R_DrawSpanMaskedAddClamp)(void);
 
 // [RH] Span blit into an interleaved intermediate buffer
 extern void (*R_DrawColumnHoriz)(void);
-void R_DrawMaskedColumnHoriz (const BYTE *column, const FTexture::Span *spans);
 
 // [RH] Initialize the above pointers
 void R_InitColumnDrawers ();
@@ -183,6 +182,7 @@ extern void (*rt_map4cols)(int sx, int yl, int yh);
 #define rt_addclamp4cols	rt_addclamp4cols_c
 #endif
 
+void rt_flip_posts();
 void rt_draw4cols (int sx);
 
 // [RH] Preps the temporary horizontal buffer.

src/r_drawt.cpp

@@ -838,6 +838,21 @@ void rt_tlaterevsubclamp4cols (int sx, int yl, int yh)
 	rt_revsubclamp4cols(sx, yl, yh);
 }
 
+// Reorder the posts so that they get drawn top-to-bottom instead of bottom-to-top.
+void rt_flip_posts()
+{
+	unsigned int *front = horizspan[dc_x & 3];
+	unsigned int *back = dc_ctspan[dc_x & 3] - 2;
+
+	while (front < back)
+	{
+		swapvalues(front[0], back[0]);
+		swapvalues(front[1], back[1]);
+		front += 2;
+		back -= 2;
+	}
+}
+
 // Copies all spans in all four columns to the screen starting at sx.
 // sx should be dword-aligned.
 void rt_draw4cols (int sx)
@@ -1103,101 +1118,3 @@ void R_FillColumnHorizP (void)
 		dest += 8;
 	} while (--count);
 }
-
-// Same as R_DrawMaskedColumn() except that it always uses R_DrawColumnHoriz().
-
-void R_DrawMaskedColumnHoriz (const BYTE *column, const FTexture::Span *span)
-{
-	const fixed_t texturemid = FLOAT2FIXED(dc_texturemid);
-	while (span->Length != 0)
-	{
-		const int length = span->Length;
-		const int top = span->TopOffset;
-
-		// calculate unclipped screen coordinates for post
-		dc_yl = xs_RoundToInt(sprtopscreen + spryscale * top);
-		dc_yh = xs_RoundToInt(sprtopscreen + spryscale * (top + length) - 1);
-
-		if (sprflipvert)
-		{
-			swapvalues (dc_yl, dc_yh);
-		}
-
-		if (dc_yh >= mfloorclip[dc_x])
-		{
-			dc_yh = mfloorclip[dc_x] - 1;
-		}
-		if (dc_yl < mceilingclip[dc_x])
-		{
-			dc_yl = mceilingclip[dc_x];
-		}
-
-		if (dc_yl <= dc_yh)
-		{
-			if (sprflipvert)
-			{
-				dc_texturefrac = (dc_yl*dc_iscale) - (top << FRACBITS)
-					- fixed_t(CenterY * dc_iscale) - texturemid;
-				const fixed_t maxfrac = length << FRACBITS;
-				while (dc_texturefrac >= maxfrac)
-				{
-					if (++dc_yl > dc_yh)
-						goto nextpost;
-					dc_texturefrac += dc_iscale;
-				}
-				fixed_t endfrac = dc_texturefrac + (dc_yh-dc_yl)*dc_iscale;
-				while (endfrac < 0)
-				{
-					if (--dc_yh < dc_yl)
-						goto nextpost;
-					endfrac -= dc_iscale;
-				}
-			}
-			else
-			{
-				dc_texturefrac = texturemid - (top << FRACBITS)
-					+ (dc_yl*dc_iscale) - fixed_t((CenterY-1) * dc_iscale);
-				while (dc_texturefrac < 0)
-				{
-					if (++dc_yl > dc_yh)
-						goto nextpost;
-					dc_texturefrac += dc_iscale;
-				}
-				fixed_t endfrac = dc_texturefrac + (dc_yh-dc_yl)*dc_iscale;
-				const fixed_t maxfrac = length << FRACBITS;
-				if (dc_yh < mfloorclip[dc_x]-1 && endfrac < maxfrac - dc_iscale)
-				{
-					dc_yh++;
-				}
-				else while (endfrac >= maxfrac)
-				{
-					if (--dc_yh < dc_yl)
-						goto nextpost;
-					endfrac -= dc_iscale;
-				}
-			}
-			dc_source = column + top;
-			dc_dest = ylookup[dc_yl] + dc_x + dc_destorg;
-			dc_count = dc_yh - dc_yl + 1;
-			hcolfunc_pre ();
-		}
-nextpost:
-		span++;
-	}
-
-	if (sprflipvert)
-	{
-		unsigned int *front = horizspan[dc_x&3];
-		unsigned int *back = dc_ctspan[dc_x&3] - 2;
-
-		// Reorder the posts so that they get drawn top-to-bottom
-		// instead of bottom-to-top.
-		while (front < back)
-		{
-			swapvalues (front[0], back[0]);
-			swapvalues (front[1], back[1]);
-			front += 2;
-			back -= 2;
-		}
-	}
-}

src/r_segs.cpp

@@ -173,7 +173,7 @@ CVAR(Bool, r_drawmirrors, true, 0)
 float *MaskedSWall;
 float MaskedScaleY;
 
-static void BlastMaskedColumn (void (*blastfunc)(const BYTE *pixels, const FTexture::Span *spans), FTexture *tex)
+static void BlastMaskedColumn (FTexture *tex, bool useRt)
 {
 	// calculate lighting
 	if (fixedcolormap == NULL && fixedlightlev < 0)
@@ -198,7 +198,7 @@ static void BlastMaskedColumn (void (*blastfunc)(const BYTE *pixels, const FText
 	// draw the texture
 	const FTexture::Span *spans;
 	const BYTE *pixels = tex->GetColumn (maskedtexturecol[dc_x] >> FRACBITS, &spans);
-	blastfunc (pixels, spans);
+	R_DrawMaskedColumn(pixels, spans, useRt);
 	rw_light += rw_lightstep;
 	spryscale += rw_scalestep;
 }
@@ -441,7 +441,7 @@ void R_RenderMaskedSegRange (drawseg_t *ds, int x1, int x2)
 		{
 			for (dc_x = x1; dc_x < x2; ++dc_x)
 			{
-				BlastMaskedColumn (R_DrawMaskedColumn, tex);
+				BlastMaskedColumn (tex, false);
 			}
 		}
 		else
@@ -456,24 +456,24 @@ void R_RenderMaskedSegRange (drawseg_t *ds, int x1, int x2)
 
 			while ((dc_x < stop) && (dc_x & 3))
 			{
-				BlastMaskedColumn (R_DrawMaskedColumn, tex);
+				BlastMaskedColumn (tex, false);
 				dc_x++;
 			}
 
 			while (dc_x < stop)
 			{
 				rt_initcols();
-				BlastMaskedColumn (R_DrawMaskedColumnHoriz, tex); dc_x++;
+				BlastMaskedColumn (tex, true); dc_x++;
-				BlastMaskedColumn (R_DrawMaskedColumnHoriz, tex); dc_x++;
+				BlastMaskedColumn (tex, true); dc_x++;
-				BlastMaskedColumn (R_DrawMaskedColumnHoriz, tex); dc_x++;
+				BlastMaskedColumn (tex, true); dc_x++;
-				BlastMaskedColumn (R_DrawMaskedColumnHoriz, tex);
+				BlastMaskedColumn (tex, true);
 				rt_draw4cols (dc_x - 3);
 				dc_x++;
 			}
 
 			while (dc_x < x2)
 			{
-				BlastMaskedColumn (R_DrawMaskedColumn, tex);
+				BlastMaskedColumn (tex, false);
 				dc_x++;
 			}
 		}
@@ -3245,7 +3245,7 @@ static void R_RenderDecal (side_t *wall, DBaseDecal *decal, drawseg_t *clipper,
 				{ // calculate lighting
 					dc_colormap = usecolormap->Maps + (GETPALOOKUP (rw_light, wallshade) << COLORMAPSHIFT);
 				}
-				R_WallSpriteColumn (R_DrawMaskedColumn);
+				R_WallSpriteColumn (false);
 				dc_x++;
 			}
 
@@ -3258,7 +3258,7 @@ static void R_RenderDecal (side_t *wall, DBaseDecal *decal, drawseg_t *clipper,
 				rt_initcols();
 				for (int zz = 4; zz; --zz)
 				{
-					R_WallSpriteColumn (R_DrawMaskedColumnHoriz);
+					R_WallSpriteColumn (true);
 					dc_x++;
 				}
 				rt_draw4cols (dc_x - 4);
@@ -3270,7 +3270,7 @@ static void R_RenderDecal (side_t *wall, DBaseDecal *decal, drawseg_t *clipper,
 				{ // calculate lighting
 					dc_colormap = usecolormap->Maps + (GETPALOOKUP (rw_light, wallshade) << COLORMAPSHIFT);
 				}
-				R_WallSpriteColumn (R_DrawMaskedColumn);
+				R_WallSpriteColumn (false);
 				dc_x++;
 			}
 		}

src/r_things.cpp

@@ -250,19 +250,17 @@ double	 		sprtopscreen;
 
 bool			sprflipvert;
 
-void R_DrawMaskedColumn (const BYTE *column, const FTexture::Span *span)
+void R_DrawMaskedColumn (const BYTE *column, const FTexture::Span *span, bool useRt)
 {
-	const fixed_t centeryfrac = FLOAT2FIXED(CenterY);
-	const fixed_t texturemid = FLOAT2FIXED(dc_texturemid);
 	while (span->Length != 0)
 	{
 		const int length = span->Length;
 		const int top = span->TopOffset;
 
 		// calculate unclipped screen coordinates for post
-		dc_yl = xs_RoundToInt(sprtopscreen + spryscale * top);
+		dc_yl = (int)(sprtopscreen + spryscale * top);
-		dc_yh = xs_RoundToInt(sprtopscreen + spryscale * (top + length)) - 1;
+		dc_yh = (int)(sprtopscreen + spryscale * (top + length)) - 1;
-
+		
 		if (sprflipvert)
 		{
 			swapvalues (dc_yl, dc_yh);
@@ -279,56 +277,20 @@ void R_DrawMaskedColumn (const BYTE *column, const FTexture::Span *span)
 
 		if (dc_yl <= dc_yh)
 		{
-			if (sprflipvert)
+			dc_texturefrac = FLOAT2FIXED((dc_yl + 0.5 - sprtopscreen) / spryscale);
-			{
+			dc_source = column;
-				dc_texturefrac = (dc_yl*dc_iscale) - (top << FRACBITS)
+			dc_dest = (ylookup[dc_yl] + dc_x) + dc_destorg;
-					- FixedMul (centeryfrac, dc_iscale) - texturemid;
-				const fixed_t maxfrac = length << FRACBITS;
-				while (dc_texturefrac >= maxfrac)
-				{
-					if (++dc_yl > dc_yh)
-						goto nextpost;
-					dc_texturefrac += dc_iscale;
-				}
-				fixed_t endfrac = dc_texturefrac + (dc_yh-dc_yl)*dc_iscale;
-				while (endfrac < 0)
-				{
-					if (--dc_yh < dc_yl)
-						goto nextpost;
-					endfrac -= dc_iscale;
-				}
-			}
-			else
-			{
-				dc_texturefrac = texturemid - (top << FRACBITS)
-					+ (dc_yl*dc_iscale) - FixedMul (centeryfrac-FRACUNIT, dc_iscale);
-				while (dc_texturefrac < 0)
-				{
-					if (++dc_yl > dc_yh)
-						goto nextpost;
-					dc_texturefrac += dc_iscale;
-				}
-				fixed_t endfrac = dc_texturefrac + (dc_yh-dc_yl)*dc_iscale;
-				const fixed_t maxfrac = length << FRACBITS;
-				if (dc_yh < mfloorclip[dc_x]-1 && endfrac < maxfrac - dc_iscale)
-				{
-					dc_yh++;
-				}
-				else while (endfrac >= maxfrac)
-				{
-					if (--dc_yh < dc_yl)
-						goto nextpost;
-					endfrac -= dc_iscale;
-				}
-			}
-			dc_source = column + top;
-			dc_dest = ylookup[dc_yl] + dc_x + dc_destorg;
 			dc_count = dc_yh - dc_yl + 1;
-			colfunc ();
+			if (useRt)
+				hcolfunc_pre();
+			else
+				colfunc ();
 		}
-nextpost:
 		span++;
 	}
+
+	if (sprflipvert && useRt)
+		rt_flip_posts();
 }
 
 // [ZZ]
@@ -470,7 +432,7 @@ void R_DrawVisSprite (vissprite_t *vis)
 			{
 				pixels = tex->GetColumn (frac >> FRACBITS, &spans);
 				if (ispsprite || !R_ClipSpriteColumnWithPortals(vis))
-					R_DrawMaskedColumn (pixels, spans);
+					R_DrawMaskedColumn (pixels, spans, false);
 				dc_x++;
 				frac += xiscale;
 			}
@@ -482,7 +444,7 @@ void R_DrawVisSprite (vissprite_t *vis)
 				{
 					pixels = tex->GetColumn (frac >> FRACBITS, &spans);
 					if (ispsprite || !R_ClipSpriteColumnWithPortals(vis))
-						R_DrawMaskedColumnHoriz (pixels, spans);
+						R_DrawMaskedColumn (pixels, spans, true);
 					dc_x++;
 					frac += xiscale;
 				}
@@ -493,7 +455,7 @@ void R_DrawVisSprite (vissprite_t *vis)
 			{
 				pixels = tex->GetColumn (frac >> FRACBITS, &spans);
 				if (ispsprite || !R_ClipSpriteColumnWithPortals(vis))
-					R_DrawMaskedColumn (pixels, spans);
+					R_DrawMaskedColumn (pixels, spans, false);
 				dc_x++;
 				frac += xiscale;
 			}
@@ -603,7 +565,7 @@ void R_DrawWallSprite(vissprite_t *spr)
 				dc_colormap = usecolormap->Maps + (GETPALOOKUP (rw_light, shade) << COLORMAPSHIFT);
 			}
 			if (!R_ClipSpriteColumnWithPortals(spr))
-				R_WallSpriteColumn(R_DrawMaskedColumn);
+				R_WallSpriteColumn(false);
 			dc_x++;
 		}
 
@@ -617,7 +579,7 @@ void R_DrawWallSprite(vissprite_t *spr)
 			for (int zz = 4; zz; --zz)
 			{
 				if (!R_ClipSpriteColumnWithPortals(spr))
-					R_WallSpriteColumn(R_DrawMaskedColumnHoriz);
+					R_WallSpriteColumn(true);
 				dc_x++;
 			}
 			rt_draw4cols(dc_x - 4);
@@ -630,14 +592,14 @@ void R_DrawWallSprite(vissprite_t *spr)
 				dc_colormap = usecolormap->Maps + (GETPALOOKUP (rw_light, shade) << COLORMAPSHIFT);
 			}
 			if (!R_ClipSpriteColumnWithPortals(spr))
-				R_WallSpriteColumn(R_DrawMaskedColumn);
+				R_WallSpriteColumn(false);
 			dc_x++;
 		}
 	}
 	R_FinishSetPatchStyle();
 }
 
-void R_WallSpriteColumn (void (*drawfunc)(const BYTE *column, const FTexture::Span *spans))
+void R_WallSpriteColumn (bool useRt)
 {
 	float iscale = swall[dc_x] * MaskedScaleY;
 	dc_iscale = FLOAT2FIXED(iscale);
@@ -651,7 +613,7 @@ void R_WallSpriteColumn (void (*drawfunc)(const BYTE *column, const FTexture::Sp
 	const FTexture::Span *spans;
 	column = WallSpriteTile->GetColumn (lwall[dc_x] >> FRACBITS, &spans);
 	dc_texturefrac = 0;
-	drawfunc (column, spans);
+	R_DrawMaskedColumn(column, spans, useRt);
 	rw_light += rw_lightstep;
 }
 
@@ -984,21 +946,23 @@ void R_ProjectSprite (AActor *thing, int fakeside, F3DFloor *fakefloor, F3DFloor
 		const double thingxscalemul = spriteScale.X / tex->Scale.X;
 
 		tx -= ((renderflags & RF_XFLIP) ? (tex->GetWidth() - tex->LeftOffset - 1) : tex->LeftOffset) * thingxscalemul;
-		x1 = centerx + xs_RoundToInt(tx * xscale);
+		double dtx1 = tx * xscale;
+		x1 = centerx + xs_RoundToInt(dtx1);
 
 		// off the right side?
 		if (x1 >= WindowRight)
 			return;
 
 		tx += tex->GetWidth() * thingxscalemul;
-		x2 = centerx + xs_RoundToInt(tx * xscale);
+		double dtx2 = tx * xscale;
+		x2 = centerx + xs_RoundToInt(dtx2);
 
 		// off the left side or too small?
 		if ((x2 < WindowLeft || x2 <= x1))
 			return;
 
 		xscale = spriteScale.X * xscale / tex->Scale.X;
-		iscale = (tex->GetWidth() << FRACBITS) / (x2 - x1);
+		iscale = (fixed_t)(tex->GetWidth() / (dtx2 - dtx1) * FRACUNIT);
 
 		double yscale = spriteScale.Y / tex->Scale.Y;
 
@@ -1026,8 +990,7 @@ void R_ProjectSprite (AActor *thing, int fakeside, F3DFloor *fakefloor, F3DFloor
 			vis->xiscale = iscale;
 		}
 
-		if (vis->x1 > x1)
+		vis->startfrac += (fixed_t)(vis->xiscale * (vis->x1 - centerx - dtx1 + 0.5 * thingxscalemul));
-			vis->startfrac += vis->xiscale * (vis->x1 - x1);
 	}
 	else
 	{

src/r_things.h

@@ -124,8 +124,8 @@ extern double			pspriteyscale;
 extern FTexture			*WallSpriteTile;
 
 
-void R_DrawMaskedColumn (const BYTE *column, const FTexture::Span *spans);
+void R_DrawMaskedColumn (const BYTE *column, const FTexture::Span *spans, bool useRt);
-void R_WallSpriteColumn (void (*drawfunc)(const BYTE *column, const FTexture::Span *spans));
+void R_WallSpriteColumn (bool useRt);
 
 void R_CacheSprite (spritedef_t *sprite);
 void R_SortVisSprites (int (*compare)(const void *, const void *), size_t first);

src/v_draw.cpp

@@ -299,7 +299,7 @@ void DCanvas::DrawTextureParms(FTexture *img, DrawParms &parms)
 			while ((dc_x < stop4) && (dc_x & 3))
 			{
 				pixels = img->GetColumn(frac >> FRACBITS, spanptr);
-				R_DrawMaskedColumn(pixels, spans);
+				R_DrawMaskedColumn(pixels, spans, false);
 				dc_x++;
 				frac += xiscale_i;
 			}
@@ -310,7 +310,7 @@ void DCanvas::DrawTextureParms(FTexture *img, DrawParms &parms)
 				for (int zz = 4; zz; --zz)
 				{
 					pixels = img->GetColumn(frac >> FRACBITS, spanptr);
-					R_DrawMaskedColumnHoriz(pixels, spans);
+					R_DrawMaskedColumn(pixels, spans, true);
 					dc_x++;
 					frac += xiscale_i;
 				}
@@ -320,7 +320,7 @@ void DCanvas::DrawTextureParms(FTexture *img, DrawParms &parms)
 			while (dc_x < x2_i)
 			{
 				pixels = img->GetColumn(frac >> FRACBITS, spanptr);
-				R_DrawMaskedColumn(pixels, spans);
+				R_DrawMaskedColumn(pixels, spans, false);
 				dc_x++;
 				frac += xiscale_i;
 			}