--- ray/src/cv/lampcolor.c	1991/09/12 13:26:16	1.5
+++ ray/src/cv/lampcolor.c	2003/02/22 02:07:23	2.6
@@ -1,19 +1,19 @@
-/* Copyright (c) 1991 Regents of the University of California */
-
 #ifndef lint
-static char SCCSid[] = "$SunId$ LBL";
+static const char	RCSid[] = "$Id: lampcolor.c,v 2.6 2003/02/22 02:07:23 greg Exp $";
 #endif
-
 /*
  * Program to convert lamp color from table and compute radiance.
  */
 
 #include <stdio.h>
 
+#include <math.h>
+
+#include "color.h"
+
 #define PI	3.14159265358979323846
 
 extern char	*gets(), *strcpy();
-extern double	atof();
 extern float	*matchlamp();
 
 				/* lamp parameters */
@@ -27,7 +27,7 @@ int	typecheck(), unitcheck(), geomcheck(), outpcheck()
 
 float	*lampcolor;		/* the lamp color (RGB) */
 double	unit2meter;		/* conversion from units to meters */
-double	projarea;		/* projected area for this geometry */
+double	area;			/* radiating area for this geometry */
 double	lumens;			/* total lamp lumens */
 
 struct {
@@ -36,9 +36,9 @@ struct {
 	int	(*check)();
 	char	*help;
 } param[NPARAMS] = {
-	{ "lamp type", "white", typecheck,
+	{ "lamp type", "WHITE", typecheck,
 "The lamp type is a string which corresponds to one of the types registered\n\
-in the lamp table file.  A value of \"white\" means an uncolored source,\n\
+in the lamp table file.  A value of \"WHITE\" means an uncolored source,\n\
 which may be preferable because it results in a color balanced image." },
 	{ "length unit", "meter", unitcheck,
 "Unit must be one of:  \"meter\", \"centimeter\", \"foot\", or \"inch\".\n\
@@ -173,7 +173,7 @@ compute()			/* compute lamp radiance */
 {
 	double	whiteval;
 
-	whiteval = lumens/470./projarea;
+	whiteval = lumens/area/(WHTEFFICACY*PI);
 
 	printf("Lamp color (RGB) = %f %f %f\n",
 			lampcolor[0]*whiteval,
@@ -182,13 +182,20 @@ compute()			/* compute lamp radiance */
 }
 
 
-getd(dp)			/* get a positive double from stdin */
+getd(name, dp, help)		/* get a positive double from stdin */
+char	*name;
 double	*dp;
+char	*help;
 {
 	char	buf[32];
-
+again:
+	printf("%s [%g]: ", name, *dp);
 	if (gets(buf) == NULL)
 		return(0);
+	if (buf[0] == '?') {
+		puts(help);
+		goto again;
+	}
 	if ((buf[0] < '0' || buf[0] > '9') && buf[0] != '.')
 		return(0);
 	*dp = atof(buf);
@@ -198,11 +205,11 @@ double	*dp;
 
 getpolygon()			/* get projected area for a polygon */
 {
-	static double	area = 1.0;
+	static double	parea = 1.0;
 
-	printf("Polygon area [%g]: ", area);
-	getd(&area);
-	projarea = PI*unit2meter*unit2meter * area;
+	getd("Polygon area", &parea,
+		"Enter the total radiating area of the polygon.");
+	area = unit2meter*unit2meter * parea;
 	return(1);
 }
 
@@ -211,9 +218,9 @@ getsphere()			/* get projected area for a sphere */
 {
 	static double	radius = 1.0;
 
-	printf("Sphere radius [%g]: ", radius);
-	getd(&radius);
-	projarea = 4.*PI*PI*unit2meter*unit2meter * radius*radius;
+	getd("Sphere radius", &radius,
+		"Enter the distance from the sphere's center to its surface.");
+	area = 4.*PI*unit2meter*unit2meter * radius*radius;
 	return(1);
 }
 
@@ -222,11 +229,11 @@ getcylinder()			/* get projected area for a cylinder *
 {
 	static double	length = 1.0, radius = 0.1;
 
-	printf("Cylinder length [%g]: ", length);
-	getd(&length);
-	printf("Cylinder radius [%g]: ", radius);
-	getd(&radius);
-	projarea = PI*PI*2.*PI*unit2meter*unit2meter * radius*length;
+	getd("Cylinder length", &length,
+		"Enter the length of the cylinder.");
+	getd("Cylinder radius", &radius,
+		"Enter the distance from the cylinder's axis to its surface.");
+	area = 2.*PI*unit2meter*unit2meter * radius*length;
 	return(1);
 }
 
@@ -235,8 +242,9 @@ getring()			/* get projected area for a ring */
 {
 	static double	radius = 1.0;
 
-	printf("Disk radius [%g]: ", radius);
-	getd(&radius);
-	projarea = PI*PI*unit2meter*unit2meter * radius*radius;
+	getd("Disk radius", &radius,
+"Enter the distance from the ring's center to its outer edge.\n\
+The inner radius must be zero.");
+	area = PI*unit2meter*unit2meter * radius*radius;
 	return(1);
 }