From 58269a18f0359da2f0ba3ab4da80ca87c6be1f8d Mon Sep 17 00:00:00 2001
From: Randy Heit <rheit@zdoom.fake>
Date: Sun, 1 Aug 2010 05:16:09 +0000
Subject: [PATCH] - Use a flood-fill algorithm to define polyobjects with
 PolyObj_StartLine instead of a simple   loop-following algorithm. This fixes
 the polyobjects in http://www.doomworld.com/idgames/index.php?id=6291

SVN r2482 (trunk)
---
 src/p_setup.cpp | 30 ++++++-------------------
 src/p_setup.h   | 23 +++++++++++++++++++
 src/po_man.cpp  | 60 ++++++++++++++++++++++++++++++++-----------------
 3 files changed, 69 insertions(+), 44 deletions(-)

diff --git a/src/p_setup.cpp b/src/p_setup.cpp
index 452cb0dcf5..4df7a367e0 100644
--- a/src/p_setup.cpp
+++ b/src/p_setup.cpp
@@ -128,27 +128,8 @@ FLightStack*	LightStacks;
 TArray<FMapThing> MapThingsConverted;
 
 int sidecount;
-struct sidei_t	// [RH] Only keep BOOM sidedef init stuff around for init
-{
-	union
-	{
-		// Used when unpacking sidedefs and assigning
-		// properties based on linedefs.
-		struct
-		{
-			short tag, special;
-			short alpha;
-			DWORD map;
-		} a;
+sidei_t *sidetemp;
 
-		// Used when grouping sidedefs into loops.
-		struct
-		{
-			DWORD first, next;
-			char lineside;
-		} b;
-	};
-}				*sidetemp;
 TArray<int>		linemap;
 
 bool			UsingGLNodes;
@@ -2261,9 +2242,8 @@ static void P_LoopSidedefs ()
 		sides[right].LeftSide = i;
 	}
 
-	// Throw away sidedef init info now that we're done with it
-	delete[] sidetemp;
-	sidetemp = NULL;
+	// We keep the sidedef init info around until after polyobjects are initialized,
+	// so don't delete just yet.
 }
 
 int P_DetermineTranslucency (int lumpnum)
@@ -3866,6 +3846,10 @@ void P_SetupLevel (char *lumpname, int position)
 	PO_Init ();	// Initialize the polyobjs
 	times[16].Unclock();
 
+	assert(sidetemp != NULL);
+	delete[] sidetemp;
+	sidetemp = NULL;
+
 	// if deathmatch, randomly spawn the active players
 	if (deathmatch)
 	{
diff --git a/src/p_setup.h b/src/p_setup.h
index c751c989ca..80196e3173 100644
--- a/src/p_setup.h
+++ b/src/p_setup.h
@@ -111,4 +111,27 @@ int P_TranslateSectorSpecial (int);
 int GetUDMFInt(int type, int index, const char *key);
 fixed_t GetUDMFFixed(int type, int index, const char *key);
 
+struct sidei_t	// [RH] Only keep BOOM sidedef init stuff around for init
+{
+	union
+	{
+		// Used when unpacking sidedefs and assigning
+		// properties based on linedefs.
+		struct
+		{
+			short tag, special;
+			short alpha;
+			DWORD map;
+		} a;
+
+		// Used when grouping sidedefs into loops.
+		struct
+		{
+			DWORD first, next;
+			char lineside;
+		} b;
+	};
+};
+extern sidei_t *sidetemp;
+
 #endif
diff --git a/src/po_man.cpp b/src/po_man.cpp
index c240e28fa2..93662f64ea 100644
--- a/src/po_man.cpp
+++ b/src/po_man.cpp
@@ -27,6 +27,7 @@
 #include "r_interpolate.h"
 #include "g_level.h"
 #include "po_man.h"
+#include "p_setup.h"
 
 // MACROS ------------------------------------------------------------------
 
@@ -1334,41 +1335,58 @@ static void KillSideLists ()
 	KnownPolySides.ShrinkToFit ();
 }
 
+//==========================================================================
+//
+// AddPolyVert
+//
+// Helper function for IterFindPolySides()
+//
+//==========================================================================
+
+static void AddPolyVert(TArray<DWORD> &vnum, DWORD vert)
+{
+	for (unsigned int i = vnum.Size() - 1; i-- != 0; )
+	{
+		if (vnum[i] == vert)
+		{ // Already in the set. No need to add it.
+			return;
+		}
+	}
+	vnum.Push(vert);
+}
+
 //==========================================================================
 //
 // IterFindPolySides
 //
+// Beginning with the first vertex of the starting side, for each vertex
+// in vnum, add all the sides that use it as a first vertex to the polyobj,
+// and add all their second vertices to vnum. This continues until there
+// are no new vertices in vnum.
+//
 //==========================================================================
 
 static void IterFindPolySides (FPolyObj *po, side_t *side)
 {
-	SDWORD j;
-	int i;
-	vertex_t *v1 = side->V1();
+	static TArray<DWORD> vnum;
+	unsigned int vnumat;
 
-	po->Sidedefs.Push(side);
+	assert(sidetemp != NULL);
 
-	// This for loop exists solely to avoid infinitely looping on badly
-	// formed polyobjects.
-	for (i = 0; i < numsides; i++)
+	vnum.Clear();
+	vnum.Push(DWORD(side->V1() - vertexes));
+	vnumat = 0;
+
+	while (vnum.Size() != vnumat)
 	{
-		int v2 = int(side->V2() - vertexes);
-		j = side->RightSide;
-
-		if (j == NO_SIDE)
+		DWORD sidenum = sidetemp[vnum[vnumat++]].b.first;
+		while (sidenum != NO_SIDE)
 		{
-			break;
+			po->Sidedefs.Push(&sides[sidenum]);
+			AddPolyVert(vnum, DWORD(sides[sidenum].V2() - vertexes));
+			sidenum = sidetemp[sidenum].b.next;
 		}
-		side = &sides[j];
-
-		if (side->V1() == v1)
-		{
-			return;
-		}
-		po->Sidedefs.Push(side);
 	}
-	I_Error ("IterFindPolySides: Non-closed Polyobj at linedef %d.\n",
-		side->linedef-lines);
 }