--- ray/src/gen/mkillum2.c	1991/11/08 13:17:47	1.14
+++ ray/src/gen/mkillum2.c	1992/08/13 10:03:19	2.4
@@ -26,8 +26,7 @@ char  *nm;
 	sprintf(errmsg, "(%s): cannot make illum for %s \"%s\"",
 			nm, ofun[ob->otype].funame, ob->oname);
 	error(WARNING, errmsg);
-	if (!(il->flags & IL_LIGHT))
-		printobj(il->altmat, ob);
+	printobj(il->altmat, ob);
 }
 
 
@@ -67,7 +66,20 @@ char  *nm;
 	distarr = (float *)calloc(n, 3*sizeof(float));
 	if (distarr == NULL)
 		error(SYSTEM, "out of memory in o_face");
-	mkaxes(u, v, fa->norm);
+				/* take first edge longer than sqrt(area) */
+	for (j = fa->nv-1, i = 0; i < fa->nv; j = i++) {
+		u[0] = VERTEX(fa,i)[0] - VERTEX(fa,j)[0];
+		u[1] = VERTEX(fa,i)[1] - VERTEX(fa,j)[1];
+		u[2] = VERTEX(fa,i)[2] - VERTEX(fa,j)[2];
+		if (DOT(u,u) >= fa->area-FTINY)
+			break;
+	}
+	if (i < fa->nv) {	/* got one! -- let's align our axes */
+		normalize(u);
+		fcross(v, fa->norm, u);
+	} else			/* oh well, we'll just have to wing it */
+		mkaxes(u, v, fa->norm);
+				/* now, find limits in (u,v) coordinates */
 	ur[0] = vr[0] = FHUGE;
 	ur[1] = vr[1] = -FHUGE;
 	for (i = 0; i < fa->nv; i++) {
@@ -120,7 +132,7 @@ char  *nm;
 		if (il->sampdens > 0)
 			flatout(il, distarr, nalt, nazi, u, v, fa->norm);
 		illumout(il, ob);
-	} else if (!(il->flags & IL_LIGHT))
+	} else
 		printobj(il->altmat, ob);
 				/* clean up */
 	freeface(ob);
@@ -191,7 +203,7 @@ char  *nm;
 		else
 			objerror(ob, WARNING, "diffuse distribution");
 		illumout(il, ob);
-	} else if (!(il->flags & IL_LIGHT))
+	} else
 		printobj(il->altmat, ob);
 				/* clean up */
 	free((char *)distarr);
@@ -259,7 +271,7 @@ char  *nm;
 		if (il->sampdens > 0)
 			flatout(il, distarr, nalt, nazi, u, v, co->ad);
 		illumout(il, ob);
-	} else if (!(il->flags & IL_LIGHT))
+	} else
 		printobj(il->altmat, ob);
 				/* clean up */
 	freecone(ob);