From d20775286cd10331bc845b0feac69f300c231524 Mon Sep 17 00:00:00 2001
From: havoc <havoc@d7cf8633-e32d-0410-b094-e92efae38249>
Date: Sun, 4 Feb 2007 12:54:09 +0000
Subject: [PATCH] refactored end code in Collision_Trace*BrushFloat functions
 to fix a severe logic bug that caused players to get stuck inside eachother
 in nexuiz

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@6788 d7cf8633-e32d-0410-b094-e92efae38249
---
 collision.c | 80 ++++++++++++++++++++++++++++-------------------------
 1 file changed, 42 insertions(+), 38 deletions(-)

diff --git a/collision.c b/collision.c
index 87c10b73..50812e5e 100644
--- a/collision.c
+++ b/collision.c
@@ -668,31 +668,33 @@ void Collision_TraceBrushBrushFloat(trace_t *trace, const colbrushf_t *thisbrush
 	// at this point we know the trace overlaps the brush because it was not
 	// rejected at any point in the loop above
 
-	// see if this brush can block the trace or not according to contents
-	if (trace->hitsupercontentsmask & thatbrush_start->supercontents)
+	// see if the trace started outside the brush or not
+	if (enterfrac > -1)
 	{
-		if (enterfrac == -1)
+		// started outside, and overlaps, therefore there is a collision here
+		// store out the impact information
+		if (trace->hitsupercontentsmask & thatbrush_start->supercontents)
 		{
-			trace->startsupercontents |= thatbrush_start->supercontents;
-			trace->startsolid = true;
-			if (leavefrac < 1)
-				trace->allsolid = true;
+			trace->hitsupercontents = thatbrush_start->supercontents;
+			trace->hitq3surfaceflags = hitq3surfaceflags;
+			trace->hittexture = hittexture;
+			trace->realfraction = bound(0, enterfrac, 1);
+			trace->fraction = bound(0, enterfrac2, 1);
+			if (collision_prefernudgedfraction.integer)
+				trace->realfraction = trace->fraction;
+			VectorCopy(newimpactnormal, trace->plane.normal);
 		}
-		// store out the impact information
-		trace->hitsupercontents = thatbrush_start->supercontents;
-		trace->hitq3surfaceflags = hitq3surfaceflags;
-		trace->hittexture = hittexture;
-		trace->realfraction = bound(0, enterfrac, 1);
-		trace->fraction = bound(0, enterfrac2, 1);
-		if (collision_prefernudgedfraction.integer)
-			trace->realfraction = trace->fraction;
-		VectorCopy(newimpactnormal, trace->plane.normal);
 	}
 	else
 	{
-		// this brush can not block the trace, but it can update start contents
-		if (enterfrac == -1)
-			trace->startsupercontents |= thatbrush_start->supercontents;
+		// started inside, update startsolid and friends
+		trace->startsupercontents |= thatbrush_start->supercontents;
+		if (trace->hitsupercontentsmask & thatbrush_start->supercontents)
+		{
+			trace->startsolid = true;
+			if (leavefrac < 1)
+				trace->allsolid = true;
+		}
 	}
 }
 
@@ -785,31 +787,33 @@ void Collision_TraceLineBrushFloat(trace_t *trace, const vec3_t linestart, const
 	// at this point we know the trace overlaps the brush because it was not
 	// rejected at any point in the loop above
 
-	// see if this brush can block the trace or not according to contents
-	if (trace->hitsupercontentsmask & thatbrush_start->supercontents)
+	// see if the trace started outside the brush or not
+	if (enterfrac > -1)
 	{
-		if (enterfrac == -1)
+		// started outside, and overlaps, therefore there is a collision here
+		// store out the impact information
+		if (trace->hitsupercontentsmask & thatbrush_start->supercontents)
 		{
-			trace->startsupercontents |= thatbrush_start->supercontents;
-			trace->startsolid = true;
-			if (leavefrac < 1)
-				trace->allsolid = true;
+			trace->hitsupercontents = thatbrush_start->supercontents;
+			trace->hitq3surfaceflags = hitq3surfaceflags;
+			trace->hittexture = hittexture;
+			trace->realfraction = bound(0, enterfrac, 1);
+			trace->fraction = bound(0, enterfrac2, 1);
+			if (collision_prefernudgedfraction.integer)
+				trace->realfraction = trace->fraction;
+			VectorCopy(newimpactnormal, trace->plane.normal);
 		}
-		// store out the impact information
-		trace->hitsupercontents = thatbrush_start->supercontents;
-		trace->hitq3surfaceflags = hitq3surfaceflags;
-		trace->hittexture = hittexture;
-		trace->realfraction = bound(0, enterfrac, 1);
-		trace->fraction = bound(0, enterfrac2, 1);
-		if (collision_prefernudgedfraction.integer)
-			trace->realfraction = trace->fraction;
-		VectorCopy(newimpactnormal, trace->plane.normal);
 	}
 	else
 	{
-		// this brush can not block the trace, but it can update start contents
-		if (enterfrac == -1)
-			trace->startsupercontents |= thatbrush_start->supercontents;
+		// started inside, update startsolid and friends
+		trace->startsupercontents |= thatbrush_start->supercontents;
+		if (trace->hitsupercontentsmask & thatbrush_start->supercontents)
+		{
+			trace->startsolid = true;
+			if (leavefrac < 1)
+				trace->allsolid = true;
+		}
 	}
 }
 
-- 
2.39.2