From 3da906441cc03acf05084b4ce25b9ec700cd3c34 Mon Sep 17 00:00:00 2001
From: rambetter <rambetter>
Date: Tue, 4 Jan 2011 06:48:32 +0000
Subject: [PATCH] Fixing SnapWeldVectorAccu().  By the way, the original
 SnapWeldVector() appears to be significantly broken, but I don't think it
 should be fixed at this point. I'm beginning to think that FixWinding()
 should not be called during the chop winding procedure.

git-svn-id: svn://svn.icculus.org/gtkradiant/GtkRadiant/branches/Rambetter-math-fix-experiments@407 8a3a26a2-13c4-0310-b231-cf6edde360e5
---
 tools/quake3/q3map2/brush.c | 37 ++++++++++++++++++++++---------------
 1 file changed, 22 insertions(+), 15 deletions(-)

diff --git a/tools/quake3/q3map2/brush.c b/tools/quake3/q3map2/brush.c
index bb38f83..596da29 100644
--- a/tools/quake3/q3map2/brush.c
+++ b/tools/quake3/q3map2/brush.c
@@ -277,15 +277,18 @@ void SnapWeldVector( vec3_t a, vec3_t b, vec3_t out )
 	}
 }
 
+/*
+SnapWeldVectorAccu()
+welds two vec3_accu_t's into a third, taking into account nearest-to-integer
+instead of averaging
+*/
 void SnapWeldVectorAccu(vec3_accu_t a, vec3_accu_t b, vec3_accu_t out)
 {
-	// I have very serious concerns about this function.
-	// This is a first pass where I just copy the original SnapWeldVector()
-	// and make sure it works with the higher resolution data types.
-	// TODO: Examine this function with a fine-toothed comb.
-
+	// I'm just preserving what I think was the intended logic of the original
+	// SnapWeldVector().  I'm not actually sure where this function should even
+	// be used.
 	int		i;
-	vec_accu_t	ai, bi, outi;
+	vec_accu_t	ai, bi, ad, bd;
 	
 	if (a == NULL || b == NULL || out == NULL)
 		Error("SnapWeldVectorAccu: NULL argument");
@@ -293,16 +296,20 @@ void SnapWeldVectorAccu(vec3_accu_t a, vec3_accu_t b, vec3_accu_t out)
 	for (i = 0; i < 3; i++)
 	{
 		ai = Q_rintAccu(a[i]);
-		bi = Q_rintAccu(a[i]); // Note, it's using a[i].  This is from legacy code.
+		bi = Q_rintAccu(b[i]);
+		ad = fabs(ai - a[i]);
+		bd = fabs(bi - b[i]);
 		
-		if (ai == a[i])					out[i] = a[i];
-		else if (bi == b[i])				out[i] = b[i];
-
-		else if (fabs(ai - a[i]) < fabs(bi < b[i]))	out[i] = a[i];
-		else						out[i] = b[i];
-		
-		outi = Q_rintAccu(out[i]);
-		if (fabs(outi - out[i]) <= SNAP_EPSILON)	out[i] = outi;
+		if (ad < bd)
+		{
+			if (ad < SNAP_EPSILON)	out[i] = ai;
+			else			out[i] = a[i];
+		}
+		else
+		{
+			if (bd < SNAP_EPSILON)	out[i] = bi;
+			else			out[i] = b[i];
+		}
 	}
 }