--- ray/src/util/dctimestep.c	2022/03/11 02:28:51	2.48
+++ ray/src/util/dctimestep.c	2025/06/07 05:09:46	2.55
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: dctimestep.c,v 2.48 2022/03/11 02:28:51 greg Exp $";
+static const char RCSid[] = "$Id: dctimestep.c,v 2.55 2025/06/07 05:09:46 greg Exp $";
 #endif
 /*
  * Compute time-step result using Daylight Coefficient method.
@@ -14,12 +14,11 @@ static const char RCSid[] = "$Id: dctimestep.c,v 2.48 
 #include "platform.h"
 #include "resolu.h"
 
-char	*progname;			/* global argv[0] */
-
 /* Sum together a set of images and write result to fout */
 static int
 sum_images(const char *fspec, const CMATRIX *cv, FILE *fout)
 {
+	static int	runcnt = 0;
 	int	myDT = DTfromHeader;
 	COLR	*scanline = NULL;
 	CMATRIX	*pmat = NULL;
@@ -28,8 +27,9 @@ sum_images(const char *fspec, const CMATRIX *cv, FILE 
 
 	if (cv->ncols != 1)
 		error(INTERNAL, "expected vector in sum_images()");
-	for (i = 0; i < cv->nrows; i++) {
-		const COLORV	*scv = cv_lval(cv,i);
+	for (i = cv->nrows; i-- > 0; ) {
+		const int	r = runcnt&1 ? i : cv->nrows-1 - i;
+		const COLORV	*scv = cv_lval(cv,r);
 		int		flat_file = 0;
 		char		fname[1024];
 		FILE		*fp;
@@ -39,14 +39,17 @@ sum_images(const char *fspec, const CMATRIX *cv, FILE 
 		char		*err;
 							/* check for zero */
 		if ((scv[RED] == 0) & (scv[GRN] == 0) & (scv[BLU] == 0) &&
-				(myDT != DTfromHeader) | (i < cv->nrows-1))
+				(myDT != DTfromHeader) | (i > 0))
 			continue;
 							/* open next picture */
-		sprintf(fname, fspec, i);
+		sprintf(fname, fspec, r);
 		if ((fp = fopen(fname, "rb")) == NULL) {
 			sprintf(errmsg, "cannot open picture '%s'", fname);
 			error(SYSTEM, errmsg);
 		}
+#ifdef getc_unlocked
+		flockfile(fp);
+#endif
 		dt = DTfromHeader;
 		if ((err = cm_getheader(&dt, NULL, NULL, NULL, NULL, fp)) != NULL)
 			error(USER, err);
@@ -74,7 +77,7 @@ sum_images(const char *fspec, const CMATRIX *cv, FILE 
 		}
 							/* flat file check */
 		if ((data_start = ftell(fp)) > 0 && fseek(fp, 0L, SEEK_END) == 0) {
-			flat_file = (ftell(fp) == data_start + sizeof(COLR)*xr*yr);
+			flat_file = (ftell(fp) >= data_start + sizeof(COLR)*xr*yr);
 			if (fseek(fp, data_start, SEEK_SET) < 0) {
 				sprintf(errmsg, "cannot seek on picture '%s'", fname);
 				error(SYSTEM, errmsg);
@@ -104,9 +107,39 @@ sum_images(const char *fspec, const CMATRIX *cv, FILE 
 	free(scanline);
 	i = cm_write(pmat, myDT, fout);			/* write picture */
 	cm_free(pmat);					/* free data */
+	++runcnt;					/* for zig-zagging */
 	return(i);
 }
 
+/* adjust matrix dimensions according to user size(s) */
+static int
+alt_dim(CMATRIX *cm, int nr, int nc)
+{
+	if ((nr <= 0) & (nc <= 0))
+		return(0);
+	if ((nr == cm->nrows) & (nc == cm->ncols))
+		return(0);
+	if (nr > 0) {
+		if (nc <= 0)
+			nc = cm->nrows*cm->ncols/nr;
+		if (nr*nc != cm->nrows*cm->ncols) {
+			fprintf(stderr, "Bad dimensions: %dx%d != %dx%d\n",
+					nr, nc, cm->nrows, cm->ncols);
+			return(-1);
+		}
+	} else /* nc > 0 */ {
+		nr = cm->nrows*cm->ncols/nc;
+		if (nc*nr != cm->nrows*cm->ncols) {
+			fprintf(stderr, "Bad dimensions: %d does not divide %dx%d evenly\n",
+					nc, cm->nrows, cm->ncols);
+			return(-1);
+		}
+	}
+	cm->nrows = nr;
+	cm->ncols = nc;
+	return(1);
+}
+
 /* check to see if a string contains a %d or %o specification */
 static int
 hasNumberFormat(const char *s)
@@ -145,8 +178,8 @@ main(int argc, char *argv[])
 	CMATRIX		*cmtx;		/* component vector/matrix result */
 	char		fnbuf[256];
 	int		a, i;
-
-	progname = argv[0];
+					/* set global progname */
+	fixargv0(argv[0]);
 					/* get options */
 	for (a = 1; a < argc && argv[a][0] == '-'; a++)
 		switch (argv[a][1]) {
@@ -215,7 +248,7 @@ main(int argc, char *argv[])
 		nsteps = smtx->ncols;
 						/* load BSDF */
 		if (argv[a+1][0] != '!' &&
-				(ccp = strrchr(argv[a+1], '.')) != NULL &&
+				(ccp = strrchr(argv[a+1], '.')) > argv[a+1] &&
 				!strcasecmp(ccp+1, "XML"))
 			Tmat = cm_loadBTDF(argv[a+1]);
 		else
@@ -235,7 +268,7 @@ main(int argc, char *argv[])
 	}
 						/* prepare output stream */
 	if ((ofspec != NULL) & (nsteps == 1) && hasNumberFormat(ofspec)) {
-		sprintf(fnbuf, ofspec, 1);
+		sprintf(fnbuf, ofspec, 0);
 		ofspec = fnbuf;
 	}
 	if (ofspec != NULL && !hasNumberFormat(ofspec)) {
@@ -246,7 +279,7 @@ main(int argc, char *argv[])
 		}
 		ofspec = NULL;			/* only need to open once */
 	}
-	if (hasNumberFormat(argv[a])) {		/* generating image(s) */
+	if (hasNumberFormat(argv[a])) {		/* loading image vector(s) */
 		if (outfmt != DTrgbe) {
 			error(WARNING, "changing output type to -oc");
 			outfmt = DTrgbe;
@@ -288,7 +321,7 @@ main(int argc, char *argv[])
 			}
 		else if (!sum_images(argv[a], cmtx, ofp))
 			return(1);
-	} else {				/* generating vector/matrix */
+	} else {				/* loading view matrix */
 		CMATRIX	*Vmat = cm_load(argv[a], 0, cmtx->nrows, DTfromHeader);
 		CMATRIX	*rmtx = cm_multiply(Vmat, cmtx);
 		cm_free(Vmat);
@@ -296,27 +329,8 @@ main(int argc, char *argv[])
 			const char	*wtype = (outfmt==DTascii) ? "w" : "wb";
 			for (i = 0; i < nsteps; i++) {
 				CMATRIX	*rvec = cm_column(rmtx, i);
-				if (yres > 0) {
-					if (xres <= 0)
-						xres = rvec->nrows/yres;
-					if (xres*yres != rvec->nrows) {
-						fprintf(stderr, "Bad resolution: %d != %dx%d\n",
-								rvec->nrows, xres, yres);
-						return(1);
-					}
-					rvec->nrows = yres;
-					rvec->ncols = xres;
-				} else if (xres > 0) {
-					yres = rvec->nrows/xres;
-					if (xres*yres != rvec->nrows) {
-						fprintf(stderr,
-							"Bad resolution: %d does not divide %d evenly\n",
-									xres, rvec->nrows);
-						return(1);
-					}
-					rvec->nrows = yres;
-					rvec->ncols = xres;
-				}
+				if (alt_dim(rvec, yres, xres) < 0)
+					return(1);
 				sprintf(fnbuf, ofspec, i);
 				if ((ofp = fopen(fnbuf, wtype)) == NULL) {
 					fprintf(stderr,
@@ -335,7 +349,7 @@ main(int argc, char *argv[])
 					if ((outfmt != DTrgbe) & (outfmt != DTxyze)) {
 						fprintf(ofp, "NROWS=%d\n", rvec->nrows);
 						fprintf(ofp, "NCOLS=%d\n", rvec->ncols);
-						fputs("NCOMP=3\n", ofp);
+						fputncomp(3, ofp);
 					}
 					if ((outfmt == DTfloat) | (outfmt == DTdouble))
 						fputendian(ofp);
@@ -358,6 +372,8 @@ main(int argc, char *argv[])
 #endif
 			if (outfmt != DTascii)
 				SET_FILE_BINARY(ofp);
+			if (alt_dim(rmtx, yres, xres) < 0)
+				return(1);
 			if (headout) {		/* header output */
 				newheader("RADIANCE", ofp);
 				printargs(argc, argv, ofp);
@@ -365,7 +381,7 @@ main(int argc, char *argv[])
 				if ((outfmt != DTrgbe) & (outfmt != DTxyze)) {
 					fprintf(ofp, "NROWS=%d\n", rmtx->nrows);
 					fprintf(ofp, "NCOLS=%d\n", rmtx->ncols);
-					fputs("NCOMP=3\n", ofp);
+					fputncomp(3, ofp);
 				}
 				if ((outfmt == DTfloat) | (outfmt == DTdouble))
 					fputendian(ofp);