From ebb63499e031f277062a7b8a382ffc54d956651b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gustaf=20Alh=C3=A4ll?= <gustaf@hanicef.me>
Date: Mon, 4 Nov 2024 21:07:15 +0100
Subject: [PATCH] Fix polyobject midtextures being stretched into infinity

---
 src/hardware/hw_main.c | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/src/hardware/hw_main.c b/src/hardware/hw_main.c
index 4741c6a46..e58b62113 100644
--- a/src/hardware/hw_main.c
+++ b/src/hardware/hw_main.c
@@ -954,6 +954,7 @@ static boolean HWR_BlendMidtextureSurface(FSurfaceInfo *pSurf)
 
 static void HWR_RenderMidtexture(INT32 gl_midtexture, float cliplow, float cliphigh, fixed_t worldtop, fixed_t worldbottom, fixed_t worldhigh, fixed_t worldlow, fixed_t worldtopslope, fixed_t worldbottomslope, fixed_t worldhighslope, fixed_t worldlowslope, UINT32 lightnum, FOutVector *inWallVerts)
 {
+	sector_t *front, *back;
 	FOutVector wallVerts[4];
 
 	FSurfaceInfo Surf;
@@ -963,6 +964,16 @@ static void HWR_RenderMidtexture(INT32 gl_midtexture, float cliplow, float cliph
 	if (!HWR_BlendMidtextureSurface(&Surf))
 		return;
 
+	if (gl_linedef->frontsector->heightsec != -1)
+		front = &sectors[gl_linedef->frontsector->heightsec];
+	else
+		front = gl_linedef->frontsector;
+
+	if (gl_linedef->backsector->heightsec != -1)
+		back = &sectors[gl_linedef->backsector->heightsec];
+	else
+		back = gl_linedef->backsector;
+
 	fixed_t texheight = FixedDiv(textureheight[gl_midtexture], abs(gl_sidedef->scaley_mid));
 	INT32 repeats;
 
@@ -972,15 +983,15 @@ static void HWR_RenderMidtexture(INT32 gl_midtexture, float cliplow, float cliph
 	{
 		fixed_t high, low;
 
-		if (gl_frontsector->ceilingheight > gl_backsector->ceilingheight)
-			high = gl_backsector->ceilingheight;
+		if (front->ceilingheight > back->ceilingheight)
+			high = back->ceilingheight;
 		else
-			high = gl_frontsector->ceilingheight;
+			high = front->ceilingheight;
 
-		if (gl_frontsector->floorheight > gl_backsector->floorheight)
-			low = gl_frontsector->floorheight;
+		if (front->floorheight > back->floorheight)
+			low = front->floorheight;
 		else
-			low = gl_backsector->floorheight;
+			low = back->floorheight;
 
 		repeats = (high - low) / texheight;
 		if ((high - low) % texheight)
@@ -1007,8 +1018,8 @@ static void HWR_RenderMidtexture(INT32 gl_midtexture, float cliplow, float cliph
 	if (gl_curline->polyseg)
 	{
 		// Change this when polyobjects support slopes
-		popentop = popentopslope = gl_curline->backsector->ceilingheight;
-		popenbottom = popenbottomslope = gl_curline->backsector->floorheight;
+		popentop = popentopslope = back->ceilingheight;
+		popenbottom = popenbottomslope = back->floorheight;
 	}
 	else
 	{