Use sphere culling in the base vis.

Base vis was done first for testing. Optimized base vis is down to ~12.4s
from ~16s (29% faster?).

tools/qfvis/include/vis.h

@@ -69,6 +69,7 @@ typedef enum {
 typedef struct {
 	plane_t     plane;		// normal pointing into neighbor
 	int         cluster;	// neighbor
+	sphere_t    sphere;		// bounding sphere
 	winding_t  *winding;
 	vstatus_t   status;
 	set_t      *visbits;

tools/qfvis/source/base-vis.c

@@ -86,6 +86,20 @@ SimpleFlood (portal_t *srcportal, int clusternum)
     }
 }
 
+static inline int
+test_sphere (sphere_t *sphere, plane_t *plane, int test_front)
+{
+	float       d;
+	int         pass;
+
+	d = DotProduct (sphere->center, plane->normal) - plane->dist;
+	if (test_front)
+		pass = (d >= -sphere->radius);
+	else
+		pass = (d <= sphere->radius);
+	return pass;
+}
+
 void
 BasePortalVis (void)
 {
@@ -93,7 +107,10 @@ BasePortalVis (void)
 	float		d;
     portal_t   *tp, *portal;
     winding_t  *winding;
+	int         base_mightsee = 0;
+	double      start, end;
 
+	start = Sys_DoubleTime ();
 	portalsee = set_new_size (numportals * 2);
     for (i = 0, portal = portals; i < numportals * 2; i++, portal++) {
 		portal->mightsee = set_new_size (portalclusters);
@@ -104,6 +121,11 @@ BasePortalVis (void)
 			if (j == i)
 				continue;
 
+			if (!test_sphere (&tp->sphere, &portal->plane, 1))
+				continue;	// entirely behind
+			if (!test_sphere (&portal->sphere, &tp->plane, 0))
+				continue;	// entirely behind
+
 			winding = tp->winding;
 			for (k = 0; k < winding->numpoints; k++) {
 				d = DotProduct (winding->points[k],
@@ -130,6 +152,10 @@ BasePortalVis (void)
 		clustersee = 0;
 		SimpleFlood (portal, portal->cluster);
 		portal->nummightsee = clustersee;
+		base_mightsee += clustersee;
     }
 	set_delete (portalsee);
+	end = Sys_DoubleTime ();
+	if (options.verbosity > 0)
+		printf ("base_mightsee: %d %gs\n", base_mightsee, end - start);
 }

tools/qfvis/source/qfvis.c

@@ -765,6 +765,7 @@ LoadPortals (char *name)
 	plane_t     plane;
 	portal_t   *portal;
 	winding_t  *winding;
+	sphere_t    sphere;
 	QFile	   *f;
 
 	if (!strcmp (name, "-"))
@@ -884,6 +885,8 @@ LoadPortals (char *name)
 
 		// calc plane
 		PlaneFromWinding (winding, &plane);
+		sphere = SmallestEnclosingBall((const vec_t(*)[3])winding->points,
+									   winding->numpoints);
 
 		// create forward portal
 		cluster = &clusters[clusternums[0]];
@@ -896,6 +899,7 @@ LoadPortals (char *name)
 		VectorNegate (plane.normal, portal->plane.normal);
 		portal->plane.dist = -plane.dist;
 		portal->cluster = clusternums[1];
+		portal->sphere = sphere;
 		portal++;
 
 		// create backwards portal
@@ -908,6 +912,7 @@ LoadPortals (char *name)
 		portal->winding = winding;
 		portal->plane = plane;
 		portal->cluster = clusternums[0];
+		portal->sphere = sphere;
 		portal++;
 	}