From 27b4013c185722ff1a2089e86324d2621c76d269 Mon Sep 17 00:00:00 2001
From: James R <justsomejames2@gmail.com>
Date: Fri, 9 Feb 2024 19:46:45 -0800
Subject: [PATCH] R_DrawColumn_Template: fix non-po2 column drawing

- Fix for efd017085
- To preserve tutti-frutti fix, offset drawing with
  texheight, but detect po2 with sourcelength
---
 src/r_draw_column.cpp | 21 +++++----------------
 src/r_plane.cpp       |  1 +
 src/r_segs.cpp        |  4 ++--
 src/r_things.cpp      |  2 --
 4 files changed, 8 insertions(+), 20 deletions(-)

diff --git a/src/r_draw_column.cpp b/src/r_draw_column.cpp
index 58aa7cf59..d9c1cf244 100644
--- a/src/r_draw_column.cpp
+++ b/src/r_draw_column.cpp
@@ -221,24 +221,13 @@ static void R_DrawColumnTemplate(drawcolumndata_t *dc)
 
 		// Inner loop that does the actual texture mapping, e.g. a DDA-like scaling.
 		// This is as fast as it gets.
-		heightmask = dc->texheight-1;
-		if (dc->sourcelength <= 0)
-		{
-			// Note: we need to unconditionally clamp in npow2 draw loop to avoid a CPU branch
-			// This is to just render it effectively the identity function.
-			npow2min = INT32_MIN;
-			npow2max = INT32_MAX;
-		}
-		else
-		{
-			npow2min = -1;
-			npow2max = dc->sourcelength;
-		}
+		heightmask = dc->sourcelength-1;
+		npow2min = -1;
+		npow2max = dc->sourcelength;
 
-		if (dc->texheight & heightmask)   // not a power of 2 -- killough
+		if (dc->sourcelength & heightmask)   // not a power of 2 -- killough
 		{
-			heightmask++;
-			heightmask <<= FRACBITS;
+			heightmask = dc->texheight << FRACBITS;
 
 			if (frac < 0)
 			{
diff --git a/src/r_plane.cpp b/src/r_plane.cpp
index 5f43a5872..fba7de8a3 100644
--- a/src/r_plane.cpp
+++ b/src/r_plane.cpp
@@ -707,6 +707,7 @@ static void R_DrawSkyPlane(visplane_t *pl, void(*colfunc)(drawcolumndata_t*), bo
 	dc.texturemid = skytexturemid;
 	dc.texheight = textureheight[skytexture]
 		>>FRACBITS;
+	dc.sourcelength = dc.texheight;
 
 	x = pl->minx;
 
diff --git a/src/r_segs.cpp b/src/r_segs.cpp
index f27875f6f..6f0ca5224 100644
--- a/src/r_segs.cpp
+++ b/src/r_segs.cpp
@@ -131,7 +131,7 @@ static void R_Render2sidedMultiPatchColumn(drawcolumndata_t* dc, column_t *colum
 	if (dc->yl <= dc->yh && dc->yh < vid.height && dc->yh > 0)
 	{
 		dc->source = (UINT8 *)column + 3;
-		dc->sourcelength = 0;
+		dc->sourcelength = lengthcol;
 		if (brightmap != NULL)
 		{
 			dc->brightmap = (UINT8 *)brightmap + 3;
@@ -1378,7 +1378,7 @@ static void R_DrawWallColumn(drawcolumndata_t* dc, INT32 yl, INT32 yh, fixed_t m
 	dc->source = R_GetColumn(texture, texturecolumn);
 	dc->brightmap = (brightmapped ? R_GetBrightmapColumn(texture, texturecolumn) : NULL);
 	dc->texheight = textureheight[texture] >> FRACBITS;
-	dc->sourcelength = 0;
+	dc->sourcelength = dc->texheight;
 	R_SetColumnFunc(colfunctype, dc->brightmap != NULL);
 	coldrawfunc_t* colfunccopy = colfunc;
 	drawcolumndata_t dc_copy = *dc;
diff --git a/src/r_things.cpp b/src/r_things.cpp
index 3c2e9576f..2e948db57 100644
--- a/src/r_things.cpp
+++ b/src/r_things.cpp
@@ -689,7 +689,6 @@ void R_DrawMaskedColumn(drawcolumndata_t* dc, column_t *column, column_t *bright
 		{
 			dc->source = (UINT8 *)column + 3;
 			dc->sourcelength = column->length;
-			dc->texheight = column->length;
 			if (brightmap != NULL)
 			{
 				dc->brightmap = (UINT8 *)brightmap + 3;
@@ -776,7 +775,6 @@ void R_DrawFlippedMaskedColumn(drawcolumndata_t* dc, column_t *column, column_t
 		{
 			dc->source = static_cast<UINT8*>(ZZ_Alloc(column->length));
 			dc->sourcelength = column->length;
-			dc->texheight = column->length;
 			for (s = (UINT8 *)column+2+column->length, d = dc->source; d < dc->source+column->length; --s)
 				*d++ = *s;