--- ray/src/gen/gensky.c	1989/02/02 11:16:29	1.1
+++ ray/src/gen/gensky.c	1992/03/20 12:23:38	2.4
@@ -17,7 +17,11 @@ static char SCCSid[] = "$SunId$ LBL";
 
 #include  <math.h>
 
+#include  "color.h"
 
+#ifndef atof
+extern double  atof();
+#endif
 extern char  *strcpy(), *strcat(), *malloc();
 extern double  stadj(), sdec(), sazi(), salt();
 
@@ -31,10 +35,11 @@ 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;					/* standard time */
+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  turbidity = 2.75;
@@ -53,7 +58,7 @@ main(argc, argv)
 int  argc;
 char  *argv[];
 {
-	extern double  atof();
+	extern double  fabs();
 	int  i;
 
 	progname = argv[0];
@@ -63,9 +68,15 @@ 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]);
+		day = atoi(argv[2]);
+		hour = atof(argv[3]);
+	}
 	for (i = 4; i < argc; i++)
 		if (argv[i][0] == '-' || argv[i][0] == '+')
 			switch (argv[i][1]) {
@@ -74,7 +85,7 @@ char  *argv[];
 				dosun = argv[i][0] == '+';
 				break;
 			case 'c':
-				cloudy = 1;
+				cloudy = argv[i][0] == '+' ? 2 : 1;
 				dosun = 0;
 				break;
 			case 't':
@@ -102,6 +113,11 @@ 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();
@@ -111,15 +127,17 @@ char  *argv[];
 
 computesky()			/* compute sky parameters */
 {
-	int  jd;
-	double  sd, st;
-	double  altitude, azimuth;
 					/* 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 */
+		st = hour + stadj(jd);		/* solar time */
+		altitude = salt(sd, st);
+		azimuth = sazi(sd, st);
+	}
 	sundir[0] = -sin(azimuth)*cos(altitude);
 	sundir[1] = -cos(azimuth)*cos(altitude);
 	sundir[2] = sin(altitude);
@@ -128,14 +146,19 @@ computesky()			/* compute sky parameters */
 	if (zenithbr <= 0.0)
 		if (cloudy) {
 			zenithbr = 8.6*sundir[2] + .123;
-			zenithbr *= 1000.0/683.0;
+			zenithbr *= 1000.0/SKYEFFICACY;
 		} else {
 			zenithbr = (1.376*turbidity-1.81)*tan(altitude)+0.38;
-			zenithbr *= 1000.0/683.0;
+			zenithbr *= 1000.0/SKYEFFICACY;
 		}
+	if (zenithbr < 0.0)
+		zenithbr = 0.0;
 					/* Compute horizontal radiance */
 	if (cloudy) {
-		groundbr = zenithbr*0.777778;
+		if (cloudy == 2)
+			groundbr = zenithbr;
+		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)) +
@@ -144,9 +167,10 @@ computesky()			/* compute sky parameters */
 		printf("# Ground ambient level: %f\n", groundbr);
 		if (sundir[2] > 0.0) {
 			if (sundir[2] > .16)
-				solarbr = 2.47e6 - 3.15e5/sundir[2];
+				solarbr = (1.5e9/SUNEFFICACY) *
+					(1.147 - .147/sundir[2]);
 			else
-				solarbr = 5e5;
+				solarbr = 1.5e9/SUNEFFICACY*(1.147-.147/.16);
 			groundbr += solarbr*6e-5*sundir[2]/PI;
 		} else
 			dosun = 0;
@@ -157,12 +181,10 @@ computesky()			/* compute sky parameters */
 
 printsky()			/* print out sky */
 {
-	register int  i;
-
 	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 +194,19 @@ 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 +228,7 @@ 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);
 }