From a0b2915b8fd4c253f156eb2d376ca56637ef4752 Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <c.oelckers@zdoom.fake>
Date: Sun, 6 Mar 2016 02:07:04 +0100
Subject: [PATCH] - added a heightsec change when aborting the main trace due
 to having found a target in a subtrace. - be a bit smarter about what to copy
 from a subtrace. There's 3 distinct pieces of information here: The hit
 itself, the CrossedWater setting for Boom-transfers and the CrossedWater
 setting for 3D floors.

Note: Ideally this should return all water hits it can detect, not just the first one.
---
 src/p_trace.cpp | 28 ++++++++++++++++++++--------
 src/p_trace.h   | 25 +++++++++++++++++++++++--
 2 files changed, 43 insertions(+), 10 deletions(-)

diff --git a/src/p_trace.cpp b/src/p_trace.cpp
index d8c5aa781e..ad2bb269c2 100644
--- a/src/p_trace.cpp
+++ b/src/p_trace.cpp
@@ -227,13 +227,7 @@ void FTraceInfo::EnterSectorPortal(int position, fixed_t frac, sector_t *enterse
 
 	if (newtrace.TraceTraverse(ActorMask ? PT_ADDLINES | PT_ADDTHINGS | PT_COMPATIBLE : PT_ADDLINES))
 	{
-		if (newtrace.Results->HitType != TRACE_HitNone)
-		{
-			if (newtrace.Results->Fraction < TempResults->Fraction)
-			{
-				*TempResults = *newtrace.Results;
-			}
-		}
+		Results->CopyIfCloser(TempResults);
 	}
 }
 
@@ -855,7 +849,25 @@ bool FTraceInfo::TraceTraverse (int ptflags)
 	if (TempResults->HitType != TRACE_HitNone && 
 		(Results->HitType == TRACE_HitNone || Results->Fraction > TempResults->Fraction))
 	{
-		*Results = *TempResults;
+		// We still need to do a water check here or this may get missed on occasion
+		if (Results->CrossedWater == NULL &&
+			CurSector->heightsec != NULL &&
+			CurSector->heightsec->floorplane.ZatPoint(Results->X, Results->Y) >= Results->Z)
+		{
+			// Save the result so that the water check doesn't destroy it.
+			FTraceResults *res = Results;
+			FTraceResults hsecResult;
+			Results = &hsecResult;
+
+			if (CheckSectorPlane(CurSector->heightsec, true))
+			{
+				Results->CrossedWater = &sectors[CurSector->sectornum];
+				Results->CrossedWaterPos = { Results->X, Results->Y, Results->Z };
+			}
+			Results = res;
+		}
+
+		Results->CopyIfCloser(TempResults);
 		return true;
 	}
 	else if (Results->HitType == TRACE_HitNone)
diff --git a/src/p_trace.h b/src/p_trace.h
index d02498133d..641a8c0077 100644
--- a/src/p_trace.h
+++ b/src/p_trace.h
@@ -36,6 +36,7 @@
 
 #include <stddef.h>
 #include "actor.h"
+#include "cmdlib.h"
 #include "textures/textures.h"
 
 struct sector_t;
@@ -70,7 +71,7 @@ struct FTraceResults
 
 	fixed_t Distance;
 	fixed_t Fraction;
-	
+
 	AActor *Actor;		// valid if hit an actor
 
 	line_t *Line;		// valid if hit a line
@@ -78,12 +79,32 @@ struct FTraceResults
 	BYTE Tier;
 	bool unlinked;		// passed through a portal without static offset.
 	ETraceResult HitType;
+	F3DFloor *ffloor;
+
 	sector_t *CrossedWater;		// For Boom-style, Transfer_Heights-based deep water
 	fixedvec3 CrossedWaterPos;	// remember the position so that we can use it for spawning the splash
 	F3DFloor *Crossed3DWater;	// For 3D floor-based deep water
 	fixedvec3 Crossed3DWaterPos;
-	F3DFloor *ffloor;
+
+	void CopyIfCloser(FTraceResults *other)
+	{
+		if (other->Distance < Distance || HitType == TRACE_HitNone)
+		{
+			memcpy(this, other, myoffsetof(FTraceResults, CrossedWater));
+		}
+		if (CrossedWater == NULL && other->CrossedWater != NULL)
+		{
+			CrossedWater = other->CrossedWater;
+			CrossedWaterPos = other->CrossedWaterPos;
+		}
+		if (Crossed3DWater == NULL && other->Crossed3DWater != NULL)
+		{
+			Crossed3DWater = other->Crossed3DWater;
+			Crossed3DWaterPos = other->Crossed3DWaterPos;
+		}
+	}
 };
+	
 
 enum
 {