--- ray/src/gen/gensky.c	1990/03/12 09:49:25	1.3
+++ 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";
@@ -17,6 +17,7 @@ static char SCCSid[] = "$SunId$ LBL";
 
 #include  <math.h>
 
+#include  "color.h"
 
 extern char  *strcpy(), *strcat(), *malloc();
 extern double  stadj(), sdec(), sazi(), salt();
@@ -31,19 +32,23 @@ extern double  s_latitude;
 extern double  s_longitude;
 extern double  s_meridian;
 					/* required values */
-int  month, day;
-double  hour;
+int  month, day;				/* date */
+double  hour;					/* time */
+int  tsolar;					/* 0=standard, 1=solar */
+double  altitude, azimuth;			/* or solar angles */
 					/* default values */
-int  cloudy = 0;
+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];
@@ -53,7 +58,6 @@ main(argc, argv)
 int  argc;
 char  *argv[];
 {
-	extern double  atof();
 	int  i;
 
 	progname = argv[0];
@@ -63,9 +67,22 @@ char  *argv[];
 	}
 	if (argc < 4)
 		userror("arg count");
-	month = atoi(argv[1]);
-	day = atoi(argv[2]);
-	hour = atof(argv[3]);
+	if (!strcmp(argv[1], "-ang")) {
+		altitude = atof(argv[2]) * (PI/180);
+		azimuth = atof(argv[3]) * (PI/180);
+		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++)
 		if (argv[i][0] == '-' || argv[i][0] == '+')
 			switch (argv[i][1]) {
@@ -73,14 +90,21 @@ 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 = 1;
+				cloudy = argv[i][0] == '+' ? 2 : 1;
 				dosun = 0;
 				break;
 			case 't':
 				turbidity = atof(argv[++i]);
 				break;
 			case 'b':
+			case 'B':
+				u_zenith = argv[i][1]=='B' ? -1 : 1;
 				zenithbr = atof(argv[++i]);
 				break;
 			case 'g':
@@ -102,6 +126,11 @@ char  *argv[];
 		else
 			userror("bad option");
 
+	if (fabs(s_meridian-s_longitude) > 30*PI/180)
+		fprintf(stderr,
+	"%s: warning: %.1f hours btwn. standard meridian and longitude\n",
+			progname, (s_longitude-s_meridian)*12/PI);
+
 	printhead(argc, argv);
 
 	computesky();
@@ -111,48 +140,70 @@ char  *argv[];
 
 computesky()			/* compute sky parameters */
 {
-	int  jd;
-	double  sd, st;
-	double  altitude, azimuth;
+	double	normfactor;
 					/* compute solar direction */
-	jd = jdate(month, day);			/* Julian date */
-	sd = sdec(jd);				/* solar declination */
-	st = hour + stadj(jd);			/* solar time */
-	altitude = salt(sd, st);
-	azimuth = sazi(sd, st);
+	if (month) {			/* from date and time */
+		int  jd;
+		double  sd, st;
+
+		jd = jdate(month, day);		/* Julian date */
+		sd = sdec(jd);			/* solar declination */
+		if (tsolar)			/* solar time */
+			st = hour;
+		else
+			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 *= 1000.0/683.0;
-		} else {
+		else
 			zenithbr = (1.376*turbidity-1.81)*tan(altitude)+0.38;
-			zenithbr *= 1000.0/683.0;
-		}
-	if (zenithbr < 0.0)
-		zenithbr = 0.0;
-					/* Compute horizontal radiance */
-	if (cloudy) {
-		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(PI/2.0-altitude)/F2/PI;
-		printf("# Ground ambient level: %f\n", groundbr);
-		if (sundir[2] > 0.0) {
-			if (sundir[2] > .16)
-				solarbr = 2.47e6 - 3.15e5/sundir[2];
-			else
-				solarbr = 5e5;
-			groundbr += solarbr*6e-5*sundir[2]/PI;
-		} else
-			dosun = 0;
+		if (zenithbr < 0.0)
+			zenithbr = 0.0;
+		else
+			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;
 }
 
@@ -162,7 +213,7 @@ printsky()			/* print out sky */
 	if (dosun) {
 		printf("\nvoid light solar\n");
 		printf("0\n0\n");
-		printf("3 %f %f %f\n", solarbr, solarbr, solarbr);
+		printf("3 %.2e %.2e %.2e\n", solarbr, solarbr, solarbr);
 		printf("\nsolar source sun\n");
 		printf("0\n0\n");
 		printf("4 %f %f %f 0.5\n", sundir[0], sundir[1], sundir[2]);
@@ -172,17 +223,19 @@ printsky()			/* print out sky */
 	printf("2 skybright skybright.cal\n");
 	printf("0\n");
 	if (cloudy)
-		printf("3 1 %f %f\n", zenithbr, groundbr);
+		printf("3 %d %.2e %.2e\n", cloudy, zenithbr, groundbr);
 	else
-		printf("7 -1 %f %f %f %f %f %f\n", zenithbr, groundbr, F2,
-				sundir[0], sundir[1], sundir[2]);
+		printf("7 -1 %.2e %.2e %.2e %f %f %f\n", zenithbr, groundbr,
+				F2, sundir[0], sundir[1], sundir[2]);
 }
 
 
 printdefaults()			/* print default values */
 {
-	if (cloudy)
+	if (cloudy == 1)
 		printf("-c\t\t\t\t# Cloudy sky\n");
+	else if (cloudy == 2)
+		printf("+c\t\t\t\t# Uniform cloudy sky\n");
 	else if (dosun)
 		printf("+s\t\t\t\t# Sunny sky with sun\n");
 	else
@@ -204,6 +257,7 @@ char  *msg;
 	if (msg != NULL)
 		fprintf(stderr, "%s: Use error - %s\n", progname, msg);
 	fprintf(stderr, "Usage: %s month day hour [options]\n", progname);
+	fprintf(stderr, "   Or: %s -ang altitude azimuth [options]\n", progname);
 	fprintf(stderr, "   Or: %s -defaults\n", progname);
 	exit(1);
 }