From: Rudolf Polzer <divverent@xonotic.org>
Date: Wed, 23 Nov 2011 08:44:05 +0000 (+0100)
Subject: audit all uses of ClipWindingEpsilon and choose the strict variant or not, and explai... 
X-Git-Tag: xonotic-v0.6.0~52
X-Git-Url: https://git.rm.cloudns.org/?a=commitdiff_plain;h=6b01d68ba6e22e65795a25225a5b5ae30a38bd95;p=xonotic%2Fnetradiant.git

audit all uses of ClipWindingEpsilon and choose the strict variant or not, and explain why
---

diff --git a/tools/quake3/q3map2/brush.c b/tools/quake3/q3map2/brush.c
index b7c50f4c..eefaa75f 100644
--- a/tools/quake3/q3map2/brush.c
+++ b/tools/quake3/q3map2/brush.c
@@ -1027,8 +1027,8 @@ void SplitBrush( brush_t *brush, int planenum, brush_t **front, brush_t **back )
 		w = s->winding;
 		if (!w)
 			continue;
-		ClipWindingEpsilon (w, plane->normal, plane->dist,
-			0 /*PLANESIDE_EPSILON*/, &cw[0], &cw[1]);
+		ClipWindingEpsilonStrict (w, plane->normal, plane->dist,
+			0 /*PLANESIDE_EPSILON*/, &cw[0], &cw[1]); /* strict, in parallel case we get the face back because it also is the midwinding */
 		for (j=0 ; j<2 ; j++)
 		{
 			if (!cw[j])
diff --git a/tools/quake3/q3map2/decals.c b/tools/quake3/q3map2/decals.c
index a130334f..b500eefd 100644
--- a/tools/quake3/q3map2/decals.c
+++ b/tools/quake3/q3map2/decals.c
@@ -594,7 +594,7 @@ static void ProjectDecalOntoWinding( decalProjector_t *dp, mapDrawSurface_t *ds,
 	for( i = 0; i < dp->numPlanes; i++ )
 	{
 		/* chop winding by the plane */
-		ClipWindingEpsilon( w, dp->planes[ i ], dp->planes[ i ][ 3 ], 0.0625f, &front, &back );
+		ClipWindingEpsilonStrict( w, dp->planes[ i ], dp->planes[ i ][ 3 ], 0.0625f, &front, &back ); /* strict, if identical plane we don't want to keep it */
 		FreeWinding( w );
 		
 		/* lose the front fragment */
diff --git a/tools/quake3/q3map2/facebsp.c b/tools/quake3/q3map2/facebsp.c
index 16997842..2e4ffffe 100644
--- a/tools/quake3/q3map2/facebsp.c
+++ b/tools/quake3/q3map2/facebsp.c
@@ -295,8 +295,8 @@ void BuildFaceTree_r( node_t *node, face_t *list )
 		/* switch on side */
 		if( side == SIDE_CROSS )
 		{
-			ClipWindingEpsilon( split->w, plane->normal, plane->dist, CLIP_EPSILON * 2,
-				&frontWinding, &backWinding );
+			ClipWindingEpsilonStrict( split->w, plane->normal, plane->dist, CLIP_EPSILON * 2,
+				&frontWinding, &backWinding ); /* strict; if no winding is left, we have a "virtually identical" plane and don't want to split by it */
 			if( frontWinding ) {
 				newFace = AllocBspFace();
 				newFace->w = frontWinding;
diff --git a/tools/quake3/q3map2/fog.c b/tools/quake3/q3map2/fog.c
index c9ee6e25..ed59d7eb 100644
--- a/tools/quake3/q3map2/fog.c
+++ b/tools/quake3/q3map2/fog.c
@@ -408,7 +408,7 @@ qboolean ChopFaceSurfaceByBrush( entity_t *e, mapDrawSurface_t *ds, brush_t *b )
 			continue;
 		
 		/* general case */
-		ClipWindingEpsilon( w, plane->normal, plane->dist, ON_EPSILON, &front, &back );
+		ClipWindingEpsilonStrict( w, plane->normal, plane->dist, ON_EPSILON, &front, &back ); /* strict; if plane is "almost identical" to face, both ways to continue can be wrong, so we better not fog it */
 		FreeWinding( w );
 		
 		if( back == NULL )
diff --git a/tools/quake3/q3map2/portals.c b/tools/quake3/q3map2/portals.c
index 2efc1db4..e16c12c7 100644
--- a/tools/quake3/q3map2/portals.c
+++ b/tools/quake3/q3map2/portals.c
@@ -410,7 +410,7 @@ void SplitNodePortals (node_t *node)
 // cut the portal into two portals, one on each side of the cut plane
 //
 		ClipWindingEpsilon (p->winding, plane->normal, plane->dist,
-			SPLIT_WINDING_EPSILON, &frontwinding, &backwinding);
+			SPLIT_WINDING_EPSILON, &frontwinding, &backwinding); /* not strict, we want to always keep one of them even if coplanar */
 
 		if (frontwinding && WindingIsTiny(frontwinding))
 		{
diff --git a/tools/quake3/q3map2/surface.c b/tools/quake3/q3map2/surface.c
index 5914c40f..e2ec8909 100644
--- a/tools/quake3/q3map2/surface.c
+++ b/tools/quake3/q3map2/surface.c
@@ -1356,7 +1356,7 @@ static void SubdivideFace_r( entity_t *e, brush_t *brush, side_t *side, winding_
 		if( (subCeil - subFloor) > subdivisions )
 		{
 			/* clip the winding */
-			ClipWindingEpsilon( w, planeNormal, d, epsilon, &frontWinding, &backWinding );
+			ClipWindingEpsilon( w, planeNormal, d, epsilon, &frontWinding, &backWinding ); /* not strict; we assume we always keep a winding */
 
 			/* the clip may not produce two polygons if it was epsilon close */
 			if( frontWinding == NULL )
@@ -1498,8 +1498,14 @@ void ClipSideIntoTree_r( winding_t *w, side_t *side, node_t *node )
 		}
 
 		plane = &mapplanes[ node->planenum ];
-		ClipWindingEpsilon ( w, plane->normal, plane->dist,
-				ON_EPSILON, &front, &back );
+		ClipWindingEpsilonStrict ( w, plane->normal, plane->dist,
+				ON_EPSILON, &front, &back ); /* strict, we handle the "winding disappeared" case */
+		if(!front && !back)
+		{
+			/* in doubt, register it in both nodes */
+			front = CopyWinding(w);
+			back = CopyWinding(w);
+		}
 		FreeWinding( w );
 
 		ClipSideIntoTree_r( front, side, node->children[0] );
@@ -2108,7 +2114,7 @@ int FilterWindingIntoTree_r( winding_t *w, mapDrawSurface_t *ds, node_t *node )
 		}
 		
 		/* clip the winding by this plane */
-		ClipWindingEpsilonStrict( w, plane1, plane1[ 3 ], ON_EPSILON, &front, &back );
+		ClipWindingEpsilonStrict( w, plane1, plane1[ 3 ], ON_EPSILON, &front, &back ); /* strict; we handle the "winding disappeared" case */
 		
 		/* filter by this plane */
 		refs = 0;