--- ray/src/common/instance.c	1991/05/29 17:11:32	1.7
+++ ray/src/common/instance.c	1993/02/02 13:24:50	2.3
@@ -16,6 +16,8 @@ static char SCCSid[] = "$SunId$ LBL";
 
 #include  "instance.h"
 
+#define  IO_ILLEGAL	(IO_FILES|IO_INFO)
+
 static SCENE  *slist = NULL;		/* list of loaded octrees */
 
 
@@ -28,7 +30,7 @@ int  flags;
 	char  *pathname;
 	register SCENE  *sc;
 
-	flags &= ~(IO_FILES|IO_INFO);		/* not allowed */
+	flags &= ~IO_ILLEGAL;		/* not allowed */
 	for (sc = slist; sc != NULL; sc = sc->next)
 		if (!strcmp(sname, sc->name)) {
 			if ((sc->ldflags & flags) == flags)
@@ -41,6 +43,11 @@ int  flags;
 			error(SYSTEM, "out of memory in getscene");
 		sc->name = savestr(sname);
 		sc->ldflags = 0;
+		sc->scube.cutree = EMPTY;
+		sc->scube.cuorg[0] = sc->scube.cuorg[1] =
+				sc->scube.cuorg[2] = 0.;
+		sc->scube.cusize = 0.;
+		sc->firstobj = sc->nobjs = 0;
 		sc->next = slist;
 		slist = sc;
 	}
@@ -48,7 +55,12 @@ int  flags;
 		sprintf(errmsg, "cannot find octree file \"%s\"", sname);
 		error(USER, errmsg);
 	}
-	readoct(pathname, flags & ~sc->ldflags, &sc->scube, NULL);
+	flags &= ~sc->ldflags;		/* skip what's already loaded */
+	if (flags & IO_SCENE)
+		sc->firstobj = nobjects;
+	readoct(pathname, flags, &sc->scube, NULL);
+	if (flags & IO_SCENE)
+		sc->nobjs = nobjects - sc->firstobj;
 	sc->ldflags |= flags;
 	return(sc);
 }
@@ -61,6 +73,7 @@ int  flags;
 {
 	register INSTANCE  *in;
 
+	flags &= ~IO_ILLEGAL;		/* not allowed */
 	if ((in = (INSTANCE *)o->os) == NULL) {
 		if ((in = (INSTANCE *)malloc(sizeof(INSTANCE))) == NULL)
 			error(SYSTEM, "out of memory in getinstance");
@@ -85,5 +98,8 @@ int  flags;
 freeinstance(o)		/* free memory associated with instance */
 OBJREC  *o;
 {
+	if (o->os == NULL)
+		return;
 	free(o->os);
+	o->os = NULL;
 }