Fixed:

- Issues with negative texture scales in the OpenGL renderer
- Regression related to horizontal texture scaling
- Regression related to the rendering of vertically flipped textures

src/hardware/hw_main.c

@@ -1167,10 +1167,21 @@ static void HWR_ProcessSeg(void) // Sort of like GLWall::Process in GZDoom
 		if ((worldhighslope < worldtopslope || worldhigh < worldtop) && gl_toptexture)
 		{
 			grTex = HWR_GetTexture(gl_toptexture);
-			xscale = FixedToFloat(gl_sidedef->scalex_top);
+			xscale = FixedToFloat(abs(gl_sidedef->scalex_top));
-			yscale = FixedToFloat(gl_sidedef->scaley_top);
+			yscale = FixedToFloat(abs(gl_sidedef->scaley_top));
 
-			fixed_t texheight = FixedDiv(textureheight[gl_toptexture], gl_sidedef->scaley_top);
+			fixed_t offsetx_top = gl_sidedef->offsetx_top;
+
+			float left = cliplow * xscale;
+			float right = cliphigh * xscale;
+			if (gl_sidedef->scalex_top < 0)
+			{
+				left = -left;
+				right = -right;
+				offsetx_top = -offsetx_top;
+			}
+
+			fixed_t texheight = FixedDiv(textureheight[gl_toptexture], abs(gl_sidedef->scaley_top));
 
 			// PEGGING
 			if (gl_linedef->flags & ML_DONTPEGTOP)
@@ -1182,15 +1193,18 @@ static void HWR_ProcessSeg(void) // Sort of like GLWall::Process in GZDoom
 
 			texturevpeg *= yscale;
 
-			texturevpeg += gl_sidedef->rowoffset + gl_sidedef->offsety_top;
+			if (gl_sidedef->scaley_top < 0)
+				texturevpeg -= gl_sidedef->rowoffset + gl_sidedef->offsety_top;
+			else
+				texturevpeg += gl_sidedef->rowoffset + gl_sidedef->offsety_top;
 
 			// This is so that it doesn't overflow and screw up the wall, it doesn't need to go higher than the texture's height anyway
 			texturevpeg %= texheight;
 
 			wallVerts[3].t = wallVerts[2].t = texturevpeg * grTex->scaleY;
 			wallVerts[0].t = wallVerts[1].t = (texturevpeg + (gl_frontsector->ceilingheight - gl_backsector->ceilingheight) * yscale) * grTex->scaleY;
-			wallVerts[0].s = wallVerts[3].s = ((cliplow * xscale) + gl_sidedef->offsetx_top) * grTex->scaleX;
+			wallVerts[0].s = wallVerts[3].s = (left + offsetx_top) * grTex->scaleX;
-			wallVerts[2].s = wallVerts[1].s = ((cliphigh * xscale) + gl_sidedef->offsetx_top) * grTex->scaleX;
+			wallVerts[2].s = wallVerts[1].s = (right + offsetx_top) * grTex->scaleX;
 
 			// Adjust t value for sloped walls
 			if (!(gl_linedef->flags & ML_SKEWTD))
@@ -1215,6 +1229,14 @@ static void HWR_ProcessSeg(void) // Sort of like GLWall::Process in GZDoom
 				wallVerts[2].t = wallVerts[1].t - (worldtopslope - worldhighslope) * yscale * grTex->scaleY;
 			}
 
+			if (gl_sidedef->scaley_top < 0)
+			{
+				wallVerts[0].t = -wallVerts[0].t;
+				wallVerts[1].t = -wallVerts[1].t;
+				wallVerts[2].t = -wallVerts[2].t;
+				wallVerts[3].t = -wallVerts[3].t;
+			}
+
 			// set top/bottom coords
 			wallVerts[3].y = FIXED_TO_FLOAT(worldtop);
 			wallVerts[0].y = FIXED_TO_FLOAT(worldhigh);
@@ -1233,8 +1255,19 @@ static void HWR_ProcessSeg(void) // Sort of like GLWall::Process in GZDoom
 		if ((worldlowslope > worldbottomslope || worldlow > worldbottom) && gl_bottomtexture)
 		{
 			grTex = HWR_GetTexture(gl_bottomtexture);
-			xscale = FixedToFloat(gl_sidedef->scalex_bottom);
+			xscale = FixedToFloat(abs(gl_sidedef->scalex_bottom));
-			yscale = FixedToFloat(gl_sidedef->scaley_bottom);
+			yscale = FixedToFloat(abs(gl_sidedef->scaley_bottom));
+
+			fixed_t offsetx_bottom = gl_sidedef->offsetx_bottom;
+
+			float left = cliplow * xscale;
+			float right = cliphigh * xscale;
+			if (gl_sidedef->scalex_bottom < 0)
+			{
+				left = -left;
+				right = -right;
+				offsetx_bottom = -offsetx_bottom;
+			}
 
 			// PEGGING
 			if (!(gl_linedef->flags & ML_DONTPEGBOTTOM))
@@ -1246,15 +1279,18 @@ static void HWR_ProcessSeg(void) // Sort of like GLWall::Process in GZDoom
 
 			texturevpeg *= yscale;
 
-			texturevpeg += gl_sidedef->rowoffset + gl_sidedef->offsety_bottom;
+			if (gl_sidedef->scaley_bottom < 0)
+				texturevpeg -= gl_sidedef->rowoffset + gl_sidedef->offsety_bottom;
+			else
+				texturevpeg += gl_sidedef->rowoffset + gl_sidedef->offsety_bottom;
 
 			// This is so that it doesn't overflow and screw up the wall, it doesn't need to go higher than the texture's height anyway
-			texturevpeg %= FixedDiv(textureheight[gl_bottomtexture], gl_sidedef->scaley_bottom);
+			texturevpeg %= FixedDiv(textureheight[gl_bottomtexture], abs(gl_sidedef->scaley_bottom));
 
 			wallVerts[3].t = wallVerts[2].t = texturevpeg * grTex->scaleY;
 			wallVerts[0].t = wallVerts[1].t = (texturevpeg + (gl_backsector->floorheight - gl_frontsector->floorheight) * yscale) * grTex->scaleY;
-			wallVerts[0].s = wallVerts[3].s = ((cliplow * xscale) + gl_sidedef->offsetx_bottom) * grTex->scaleX;
+			wallVerts[0].s = wallVerts[3].s = (left + offsetx_bottom) * grTex->scaleX;
-			wallVerts[2].s = wallVerts[1].s = ((cliphigh * xscale) + gl_sidedef->offsetx_bottom) * grTex->scaleX;
+			wallVerts[2].s = wallVerts[1].s = (right + offsetx_bottom) * grTex->scaleX;
 
 			// Adjust t value for sloped walls
 			if (!(gl_linedef->flags & ML_SKEWTD))
@@ -1278,6 +1314,14 @@ static void HWR_ProcessSeg(void) // Sort of like GLWall::Process in GZDoom
 				wallVerts[1].t = (texturevpeg + (worldlowslope - worldbottomslope) * yscale) * grTex->scaleY;
 			}
 
+			if (gl_sidedef->scaley_bottom < 0)
+			{
+				wallVerts[0].t = -wallVerts[0].t;
+				wallVerts[1].t = -wallVerts[1].t;
+				wallVerts[2].t = -wallVerts[2].t;
+				wallVerts[3].t = -wallVerts[3].t;
+			}
+
 			// set top/bottom coords
 			wallVerts[3].y = FIXED_TO_FLOAT(worldlow);
 			wallVerts[0].y = FIXED_TO_FLOAT(worldbottom);
@@ -1296,7 +1340,7 @@ static void HWR_ProcessSeg(void) // Sort of like GLWall::Process in GZDoom
 		if (gl_midtexture && HWR_BlendMidtextureSurface(&Surf))
 		{
 			sector_t *front, *back;
-			fixed_t texheight = FixedDiv(textureheight[gl_midtexture], gl_sidedef->scaley_mid);
+			fixed_t texheight = FixedDiv(textureheight[gl_midtexture], abs(gl_sidedef->scaley_mid));
 			INT32 repeats;
 
 			if (gl_linedef->frontsector->heightsec != -1)
@@ -1363,7 +1407,7 @@ static void HWR_ProcessSeg(void) // Sort of like GLWall::Process in GZDoom
 			// Find the wall's coordinates
 			fixed_t midtexheight = texheight * repeats;
 
-			fixed_t rowoffset = FixedDiv(gl_sidedef->rowoffset + gl_sidedef->offsety_mid, gl_sidedef->scaley_mid);
+			fixed_t rowoffset = FixedDiv(gl_sidedef->rowoffset + gl_sidedef->offsety_mid, abs(gl_sidedef->scaley_mid));
 
 			// Texture is not skewed
 			if (gl_linedef->flags & ML_NOSKEW)

src/r_segs.c

@@ -1424,20 +1424,20 @@ static void R_RenderSegLoop (void)
 {
 	angle_t angle;
 	fixed_t textureoffset;
-	size_t  pindex;
+	size_t pindex;
-	INT32     yl;
+	INT32 yl;
-	INT32     yh;
+	INT32 yh;
 
-	INT32     mid;
+	INT32 mid;
 	fixed_t texturecolumn = 0;
 	fixed_t toptexturecolumn = 0;
 	fixed_t bottomtexturecolumn = 0;
 	fixed_t oldtexturecolumn = -1;
 	fixed_t oldtexturecolumn_top = -1;
 	fixed_t oldtexturecolumn_bottom = -1;
-	INT32     top;
+	INT32 top;
-	INT32     bottom;
+	INT32 bottom;
-	INT32     i;
+	INT32 i;
 
 	fixed_t topscaley = rw_toptexturescaley;
 	fixed_t midscaley = rw_midtexturescaley;
@@ -1838,8 +1838,11 @@ static void R_RenderSegLoop (void)
 		{
 			if (oldtexturecolumn != -1)
 			{
-				rw_midtexturemid += FixedMul(rw_midtextureslide, oldtexturecolumn-texturecolumn);
+				INT32 diff = oldtexturecolumn-texturecolumn;
-				rw_midtextureback += FixedMul(rw_midtexturebackslide, oldtexturecolumn-texturecolumn);
+				if (rw_invmidtexturescalex < 0)
+					diff = -diff;
+				rw_midtexturemid += FixedMul(rw_midtextureslide, diff);
+				rw_midtextureback += FixedMul(rw_midtexturebackslide, diff);
 			}
 
 			oldtexturecolumn = texturecolumn;
@@ -1878,8 +1881,11 @@ static void R_RenderSegLoop (void)
 
 				if (oldoverlaycolumn[i] != -1)
 				{
-					rw_overlay[i].mid += FixedMul(rw_overlay[i].slide, oldoverlaycolumn[i]-overlaycolumn[i]);
+					INT32 diff = oldoverlaycolumn[i]-overlaycolumn[i];
-					rw_overlay[i].back += FixedMul(rw_overlay[i].backslide, oldoverlaycolumn[i]-overlaycolumn[i]);
+					if (rw_overlay[i].scalex < 0)
+						diff = -diff;
+					rw_overlay[i].mid += FixedMul(rw_overlay[i].slide, diff);
+					rw_overlay[i].back += FixedMul(rw_overlay[i].backslide, diff);
 				}
 
 				oldoverlaycolumn[i] = overlaycolumn[i];
@@ -2059,7 +2065,7 @@ static void R_AddOverlayTextures(fixed_t ceilingfrontslide, fixed_t floorfrontsl
 			rw_overlay[i].offsetx = sidedef->overlays[i].offsetx;
 			rw_overlay[i].offsety = sidedef->overlays[i].offsety;
 
-			rw_overlay[i].invscalex = FixedDiv(FRACUNIT, abs(rw_overlay[i].scalex));
+			rw_overlay[i].invscalex = FixedDiv(FRACUNIT, rw_overlay[i].scalex);
 
 			if (sidedef->flags & GET_SIDEFLAG_EDGENOSKEW(i))
 			{
@@ -2333,7 +2339,7 @@ void R_StoreWallRange(INT32 start, INT32 stop)
 
 	rw_midtexturescalex = sidedef->scalex_mid;
 	rw_midtexturescaley = sidedef->scaley_mid;
-	rw_invmidtexturescalex = FixedDiv(FRACUNIT, abs(rw_midtexturescalex));
+	rw_invmidtexturescalex = FixedDiv(FRACUNIT, rw_midtexturescalex);
 
 	if (!backsector)
 	{
@@ -2578,7 +2584,7 @@ void R_StoreWallRange(INT32 start, INT32 stop)
 			rw_toptexturescalex = sidedef->scalex_top;
 			rw_toptexturescaley = sidedef->scaley_top;
 
-			rw_invtoptexturescalex = FixedDiv(FRACUNIT, abs(rw_toptexturescalex));
+			rw_invtoptexturescalex = FixedDiv(FRACUNIT, rw_toptexturescalex);
 
 			if (rw_toptexturescaley < 0)
 				toprowoffset = -toprowoffset;
@@ -2618,7 +2624,7 @@ void R_StoreWallRange(INT32 start, INT32 stop)
 			rw_bottomtexturescalex = sidedef->scalex_bottom;
 			rw_bottomtexturescaley = sidedef->scaley_bottom;
 
-			rw_invbottomtexturescalex = FixedDiv(FRACUNIT, abs(rw_bottomtexturescalex));
+			rw_invbottomtexturescalex = FixedDiv(FRACUNIT, rw_bottomtexturescalex);
 
 			if (rw_bottomtexturescaley < 0)
 				botrowoffset = -botrowoffset;

src/r_things.c

@@ -704,8 +704,6 @@ static size_t flippedcolsize;
 
 void R_DrawFlippedPost(UINT8 *source, unsigned length, void (*drawcolfunc)(void))
 {
-	UINT8 *d, *s;
-
 	if (!length)
 		return;
 
@@ -717,8 +715,8 @@ void R_DrawFlippedPost(UINT8 *source, unsigned length, void (*drawcolfunc)(void)
 
 	dc_source = flippedcol;
 
-	for (s = (UINT8 *)source+length, d = flippedcol; d < flippedcol+length; --s)
+	for (UINT8 *s = (UINT8 *)source, *d = flippedcol+length-1; d >= flippedcol; s++)
-		*d++ = *s;
+		*d-- = *s;
 
 	drawcolfunc();
 }
@@ -729,7 +727,6 @@ void R_DrawFlippedMaskedColumn(column_t *column)
 	INT32 bottomscreen;
 	fixed_t basetexturemid = dc_texturemid;
 	INT32 topdelta, prevdelta = -1;
-	UINT8 *d,*s;
 
 	for (; column->topdelta != 0xff ;)
 	{
@@ -769,7 +766,7 @@ void R_DrawFlippedMaskedColumn(column_t *column)
 			dc_texturemid = basetexturemid - (topdelta<<FRACBITS);
 
 			// Still drawn by R_DrawColumn.
-			R_DrawFlippedPost((UINT8 *)column+2, column->length, colfunc);
+			R_DrawFlippedPost((UINT8 *)column+3, column->length, colfunc);
 		}
 		column = (column_t *)((UINT8 *)column + column->length + 4);
 	}