--- ray/src/gen/gensky.c	1992/03/20 15:29:10	2.5
+++ ray/src/gen/gensky.c	1993/06/04 14:30:24	2.10
@@ -1,4 +1,4 @@
-/* Copyright (c) 1986 Regents of the University of California */
+/* Copyright (c) 1992 Regents of the University of California */
 
 #ifndef lint
 static char SCCSid[] = "$SunId$ LBL";
@@ -19,9 +19,6 @@ static char SCCSid[] = "$SunId$ LBL";
 
 #include  "color.h"
 
-#ifndef atof
-extern double  atof();
-#endif
 extern char  *strcpy(), *strcat(), *malloc();
 extern double  stadj(), sdec(), sazi(), salt();
 
@@ -49,7 +46,7 @@ double  gprefl = 0.2;
 double  sundir[3];
 double  groundbr;
 double  F2;
-double  solarbr;
+double  solarbr = -1.0;
 
 char  *progname;
 char  errmsg[128];
@@ -59,7 +56,6 @@ main(argc, argv)
 int  argc;
 char  *argv[];
 {
-	extern double  fabs();
 	int  i;
 
 	progname = argv[0];
@@ -75,8 +71,14 @@ char  *argv[];
 		month = 0;
 	} else {
 		month = atoi(argv[1]);
+		if (month < 1 || month > 12)
+			userror("bad month");
 		day = atoi(argv[2]);
+		if (day < 1 || day > 31)
+			userror("bad day");
 		hour = atof(argv[3]);
+		if (hour < 0 || hour >= 24)
+			userror("bad hour");
 		tsolar = argv[3][0] == '+';
 	}
 	for (i = 4; i < argc; i++)
@@ -86,6 +88,9 @@ char  *argv[];
 				cloudy = 0;
 				dosun = argv[i][0] == '+';
 				break;
+			case 'r':
+				solarbr = atof(argv[++i]);
+				break;
 			case 'c':
 				cloudy = argv[i][0] == '+' ? 2 : 1;
 				dosun = 0;
@@ -143,6 +148,14 @@ computesky()			/* compute sky parameters */
 		altitude = salt(sd, st);
 		azimuth = sazi(sd, st);
 	}
+	if (!cloudy && altitude > 87.*PI/180.) {
+		fprintf(stderr,
+"%s: warning - sun too close to zenith, reducing altitude to 87 degrees\n",
+				progname);
+		printf(
+"# warning - sun too close to zenith, reducing altitude to 87 degrees\n");
+		altitude = 87.*PI/180.;
+	}
 	sundir[0] = -sin(azimuth)*cos(altitude);
 	sundir[1] = -cos(azimuth)*cos(altitude);
 	sundir[2] = sin(altitude);
@@ -151,7 +164,7 @@ computesky()			/* compute sky parameters */
 	if (zenithbr <= 0.0)
 		if (cloudy) {
 			zenithbr = 8.6*sundir[2] + .123;
-			zenithbr *= 1000.0/SKYEFFICACY;
+			zenithbr *= 1000.0/WHTEFFICACY;
 		} else {
 			zenithbr = (1.376*turbidity-1.81)*tan(altitude)+0.38;
 			zenithbr *= 1000.0/SKYEFFICACY;
@@ -168,14 +181,12 @@ computesky()			/* compute sky parameters */
 	} else {
 		F2 = 0.274*(0.91 + 10.0*exp(-3.0*(PI/2.0-altitude)) +
 				0.45*sundir[2]*sundir[2]);
-		groundbr = zenithbr*normsc(PI/2.0-altitude)/F2/PI;
+		groundbr = zenithbr*normsc(altitude)/F2/PI;
 		printf("# Ground ambient level: %f\n", groundbr);
-		if (sundir[2] > 0.0) {
-			if (sundir[2] > .16)
-				solarbr = (1.5e9/SUNEFFICACY) *
-					(1.147 - .147/sundir[2]);
-			else
-				solarbr = 1.5e9/SUNEFFICACY*(1.147-.147/.16);
+		if (sundir[2] > 0.0 && solarbr != 0.0) {
+			if (solarbr < 0.0)
+				solarbr = 1.5e9/SUNEFFICACY *
+				(1.147 - .147/(sundir[2]>.16?sundir[2]:.16));
 			groundbr += solarbr*6e-5*sundir[2]/PI;
 		} else
 			dosun = 0;