--- ray/src/gen/gensky.c	1992/10/02 16:11:53	2.7
+++ ray/src/gen/gensky.c	1993/06/14 13:54:26	2.12
@@ -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();
 
@@ -42,14 +39,16 @@ double  altitude, azimuth;			/* or solar angles */
 					/* default values */
 int  cloudy = 0;				/* 1=standard, 2=uniform */
 int  dosun = 1;
-double  zenithbr = -1.0;
+double  zenithbr = 0.0;
+int	u_zenith = 0;				/* -1=irradiance, 1=radiance */
 double  turbidity = 2.75;
 double  gprefl = 0.2;
 					/* computed values */
 double  sundir[3];
 double  groundbr;
 double  F2;
-double  solarbr;
+double  solarbr = 0.0;
+int	u_solar = 0;				/* -1=irradiance, 1=radiance */
 
 char  *progname;
 char  errmsg[128];
@@ -91,6 +90,11 @@ char  *argv[];
 				cloudy = 0;
 				dosun = argv[i][0] == '+';
 				break;
+			case 'r':
+			case 'R':
+				u_solar = argv[i][1]=='R' ? -1 : 1;
+				solarbr = atof(argv[++i]);
+				break;
 			case 'c':
 				cloudy = argv[i][0] == '+' ? 2 : 1;
 				dosun = 0;
@@ -99,6 +103,8 @@ char  *argv[];
 				turbidity = atof(argv[++i]);
 				break;
 			case 'b':
+			case 'B':
+				u_zenith = argv[i][1]=='B' ? -1 : 1;
 				zenithbr = atof(argv[++i]);
 				break;
 			case 'g':
@@ -134,6 +140,7 @@ char  *argv[];
 
 computesky()			/* compute sky parameters */
 {
+	double	normfactor;
 					/* compute solar direction */
 	if (month) {			/* from date and time */
 		int  jd;
@@ -147,44 +154,56 @@ computesky()			/* compute sky parameters */
 			st = hour + stadj(jd);
 		altitude = salt(sd, st);
 		azimuth = sazi(sd, st);
+		printf("# Solar altitude and azimuth: %f %f\n",
+				180./PI*altitude, 180./PI*azimuth);
 	}
+	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);
 
+					/* Compute normalization factor */
+	if (cloudy == 2)
+		normfactor = 1.0;
+	else if (cloudy == 1)
+		normfactor = 0.777778;
+	else {
+		F2 = 0.274*(0.91 + 10.0*exp(-3.0*(PI/2.0-altitude)) +
+				0.45*sundir[2]*sundir[2]);
+		normfactor = normsc(altitude)/F2/PI;
+	}
 					/* Compute zenith brightness */
-	if (zenithbr <= 0.0)
-		if (cloudy) {
+	if (u_zenith == -1)
+		zenithbr /= normfactor*PI;
+	else if (u_zenith == 0) {
+		if (cloudy)
 			zenithbr = 8.6*sundir[2] + .123;
-			zenithbr *= 1000.0/WHTEFFICACY;
-		} else {
+		else
 			zenithbr = (1.376*turbidity-1.81)*tan(altitude)+0.38;
-			zenithbr *= 1000.0/SKYEFFICACY;
-		}
-	if (zenithbr < 0.0)
-		zenithbr = 0.0;
-					/* Compute horizontal radiance */
-	if (cloudy) {
-		if (cloudy == 2)
-			groundbr = zenithbr;
+		if (zenithbr < 0.0)
+			zenithbr = 0.0;
 		else
-			groundbr = zenithbr*0.777778;
-		printf("# Ground ambient level: %f\n", groundbr);
-	} else {
-		F2 = 0.274*(0.91 + 10.0*exp(-3.0*(PI/2.0-altitude)) +
-				0.45*sundir[2]*sundir[2]);
-		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);
-			groundbr += solarbr*6e-5*sundir[2]/PI;
-		} else
-			dosun = 0;
+			zenithbr *= 1000.0/SKYEFFICACY;
 	}
+					/* Compute horizontal radiance */
+	groundbr = zenithbr*normfactor;
+	printf("# Ground ambient level: %f\n", groundbr);
+	if (sundir[2] > 0.0 && (!u_solar || solarbr > 0.0)) {
+		if (u_solar == -1)
+			solarbr /= 6e-5*sundir[2];
+		else if (u_solar == 0)
+			solarbr = 1.5e9/SUNEFFICACY *
+			(1.147 - .147/(sundir[2]>.16?sundir[2]:.16));
+		groundbr += 6e-5/PI*solarbr*sundir[2];
+	} else
+		dosun = 0;
 	groundbr *= gprefl;
 }