--- ray/src/rt/lookamb.c	1991/11/12 17:08:36	2.1
+++ ray/src/rt/lookamb.c	1992/07/16 12:08:44	2.3
@@ -18,7 +18,7 @@ static char SCCSid[] = "$SunId$ LBL";
 
 
 int  dataonly = 0;
-
+int  header = 1;
 int  reverse = 0;
 
 AMBVAL  av;
@@ -39,6 +39,9 @@ char  *argv[];
 			case 'r':
 				reverse = 1;
 				break;
+			case 'h':
+				header = 0;
+				break;
 			default:
 				fprintf(stderr, "%s: unknown option '%s'\n",
 						argv[0], argv[i]);
@@ -53,19 +56,39 @@ char  *argv[];
 		fprintf(stderr, "%s: file not found\n", argv[i]);
 		return(1);
 	}
-	if (reverse)
+	if (reverse) {
+		if (header) {
+			if (checkheader(fp, "ascii", stdout) < 0)
+				goto formaterr;
+		} else
+			printargs(argc, argv, stdout);
+		fputformat(AMBFMT, stdout);
+		putchar('\n');
+		putambmagic(stdout);
 		writamb(fp);
-	else
+	} else {
+		if (checkheader(fp, AMBFMT, header ? stdout : (FILE *)NULL) < 0)
+			goto formaterr;
+		if (!hasambmagic(fp))
+			goto formaterr;
+		if (header) {
+			fputformat("ascii", stdout);
+			putchar('\n');
+		}
 		lookamb(fp);
+	}
 	fclose(fp);
 	return(0);
+formaterr:
+	fprintf(stderr, "%s: format error on input\n", argv[0]);
+	exit(1);
 }
 
 
 lookamb(fp)			/* get ambient values from a file */
 FILE  *fp;
 {
-	while (fread((char *)&av, sizeof(AMBVAL), 1, fp) == 1) {
+	while (readambval(&av, fp)) {
 		if (dataonly) {
 			printf("%f\t%f\t%f\t", av.pos[0], av.pos[1], av.pos[2]);
 			printf("%f\t%f\t%f\t", av.dir[0], av.dir[1], av.dir[2]);
@@ -132,7 +155,7 @@ FILE  *fp;
 				&av.gdir[0], &av.gdir[1], &av.gdir[2]) != 3)
 			return;
 		av.next = NULL;
-		fwrite((char *)&av, sizeof(AMBVAL), 1, stdout);
+		writambval(&av, stdout);
 		if (ferror(stdout))
 			exit(1);
 	}