--- ray/src/ot/sphere.c	1989/02/02 10:33:06	1.1
+++ ray/src/ot/sphere.c	1991/05/22 17:01:43	1.3
@@ -64,9 +64,16 @@ register CUBE  *cu;
 #define  cent		fa
 #define  rad		fa[3]
 					/* get arguments */
+	if (o->oargs.nfargs != 4)
+		objerror(o, USER, "bad # arguments");
 	fa = o->oargs.farg;
-	if (o->oargs.nfargs != 4 || rad <= FTINY)
-		objerror(o, USER, "bad arguments");
+	if (rad < -FTINY) {
+		objerror(o, WARNING, "negative radius");
+		o->otype = o->otype == OBJ_SPHERE ?
+				OBJ_BUBBLE : OBJ_SPHERE;
+		rad = -rad;
+	} else if (rad <= FTINY)
+		objerror(o, USER, "zero radius");
 
 	d1 = ROOT3/2.0 * cu->cusize;	/* bounding radius for cube */
 
@@ -76,14 +83,14 @@ register CUBE  *cu;
 	d2 = DOT(v1,v1);
 
 	if (d2 > (rad+d1+FTINY)*(rad+d1+FTINY))	/* quick test */
-		return(0);			/* cube outside */
+		return(O_MISS);			/* cube outside */
 	
 					/* check sphere interior */
 	if (d1 < rad) {
 		if (d2 < (rad-d1-FTINY)*(rad-d1-FTINY))
-			return(0);		/* cube inside sphere */
+			return(O_MISS);		/* cube inside sphere */
 		if (d2 < (rad+FTINY)*(rad+FTINY))
-			return(1);		/* cube center inside */
+			return(O_HIT);		/* cube center inside */
 	}
 					/* find closest distance */
 	for (i = 0; i < 3; i++)
@@ -95,7 +102,7 @@ register CUBE  *cu;
 			v1[i] = 0;
 					/* final intersection check */
 	if (DOT(v1,v1) <= (rad+FTINY)*(rad+FTINY))
-		return(1);
+		return(O_HIT);
 	else
-		return(0);
+		return(O_MISS);
 }