static void
combine(void) /* combine pictures */
{
EPNODE *coldef[3], *brtdef;
COLOR *scanout;
double d;
register int i, j;
/* check defined variables */
for (j = 0; j < 3; j++) {
if (vardefined(vcolout[j]))
coldef[j] = eparse(vcolout[j]);
else
coldef[j] = NULL;
}
if (vardefined(vbrtout))
brtdef = eparse(vbrtout);
else
brtdef = NULL;
/* allocate scanline */
scanout = (COLOR *)emalloc(xres*sizeof(COLOR));
/* set input position */
yscan = ymax+MIDSCN;
/* combine files */
for (ypos = yres-1; ypos >= 0; ypos--) {
advance();
varset(vypos, '=', (double)ypos);
for (xpos = 0; xpos < xres; xpos++) {
xscan = (xpos+.5)*xmax/xres;
varset(vxpos, '=', (double)xpos);
eclock++;
if (brtdef != NULL) {
d = evalue(brtdef);
if (d < 0.0)
d = 0.0;
setcolor(scanout[xpos], d, d, d);
} else {
for (j = 0; j < 3; j++) {
if (coldef[j] != NULL) {
d = evalue(coldef[j]);
} else {
d = 0.0;
for (i = 0; i < nfiles; i++)
d += colval(input[i].scan[MIDSCN][xscan],j);
}
if (d < 0.0)
d = 0.0;
colval(scanout[xpos],j) = d;
}
}
}
if (fwritescan(scanout, xres, stdout) < 0) {
perror("write error");
quit(1);
}
}
efree((char *)scanout);
}
double
eval( /* evaluate an expression string */
char *expr
)
{
EPNODE *ep;
double rval;
ep = eparse(expr);
rval = evalue(ep);
epfree(ep);
return(rval);
}
static void
readfmt( /* read record format */
char *spec,
int output
)
{
int fd;
char *inptr;
struct field fmt;
int res;
register struct field *f;
/* check for inline format */
for (inptr = spec; *inptr; inptr++)
if (*inptr == '$')
break;
if (*inptr) /* inline */
inptr = spec;
else { /* from file */
if ((fd = open(spec, 0)) == -1) {
eputs(spec);
eputs(": cannot open\n");
quit(1);
}
res = read(fd, inpbuf+2, INBSIZ-2);
if (res <= 0 || res >= INBSIZ-1) {
eputs(spec);
if (res < 0)
eputs(": read error\n");
else if (res == 0)
eputs(": empty file\n");
else if (res >= INBSIZ-1)
eputs(": format too long\n");
quit(1);
}
close(fd);
(inptr=inpbuf+2)[res] = '\0';
}
f = &fmt; /* get fields */
while ((res = readfield(&inptr)) != F_NUL) {
f->next = (struct field *)emalloc(sizeof(struct field));
f = f->next;
f->type = res;
switch (res & F_TYP) {
case T_LIT:
f->f.sl = savqstr(inpbuf);
break;
case T_STR:
f->f.sv = getsvar(inpbuf);
break;
case T_NUM:
if (output)
f->f.ne = eparse(inpbuf);
else
f->f.nv = savestr(inpbuf);
break;
}
/* add final newline if necessary */
if (!igneol && *inptr == '\0' && inptr[-1] != '\n')
inptr = "\n";
}
f->next = NULL;
if (output)
outfmt = fmt.next;
else
inpfmt = fmt.next;
}
