--- ray/src/gen/mkillum2.c	1992/03/11 12:25:47	2.2
+++ ray/src/gen/mkillum2.c	1995/11/07 17:50:44	2.7
@@ -1,4 +1,4 @@
-/* Copyright (c) 1991 Regents of the University of California */
+/* Copyright (c) 1995 Regents of the University of California */
 
 #ifndef lint
 static char SCCSid[] = "$SunId$ LBL";
@@ -66,7 +66,21 @@ 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 ((r1 = DOT(u,u)) >= fa->area-FTINY)
+			break;
+	}
+	if (i < fa->nv) {	/* got one! -- let's align our axes */
+		r2 = 1.0/sqrt(r1);
+		u[0] *= r2; u[1] *= r2; u[2] *= r2;
+		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++) {
@@ -149,8 +163,8 @@ char  *nm;
 		nalt = nazi = 1;
 	else {
 		n = 4.*PI * il->sampdens;
-		nalt = sqrt(n/PI) + .5;
-		nazi = PI*nalt + .5;
+		nalt = sqrt(2./PI*n) + .5;
+		nazi = PI/2.*nalt + .5;
 	}
 	n = nalt*nazi;
 	distarr = (float *)calloc(n, 3*sizeof(float));
@@ -246,7 +260,7 @@ char  *nm;
 		    r1 = r3*cos(r2);
 		    r2 = r3*sin(r2);
 		    for (j = 0; j < 3; j++)
-			org[j] = CO_P0(co)[j] + r1*u[j] + r1*v[j] +
+			org[j] = CO_P0(co)[j] + r1*u[j] + r2*v[j] +
 					.001*co->ad[j];
 
 					/* send sample */