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/* See LICENSE file for copyright and license details. */
#include "stream.h"
#include "util.h"
#include <string.h>
#include <unistd.h>
USAGE("alpha-stream")
static int first = 1;
static void
process_xyza(char *output, char *restrict cbuf, char *restrict abuf,
struct stream *colour, struct stream *alpha, size_t cn, size_t an)
{
typedef double pixel_t[4];
pixel_t *restrict clr = (pixel_t *)cbuf;
pixel_t *restrict alf = (pixel_t *)abuf;
pixel_t *img = (pixel_t *)output;
size_t i, n = cn / sizeof(pixel_t);
double a1, a2;
if (first) {
memcpy(output, cbuf, cn);
first = 0;
return;
}
for (i = 0; i < n; i++, clr++, alf++, img++) {
a1 = (*img)[3];
a2 = (*clr)[3] * (*alf)[1] * (*alf)[3];
a1 *= (1 - a2);
(*img)[0] = (*img)[0] * a1 + (*clr)[0] * a2;
(*img)[1] = (*img)[1] * a1 + (*clr)[1] * a2;
(*img)[2] = (*img)[2] * a1 + (*clr)[2] * a2;
(*img)[3] = a1 + a2;
}
(void) colour;
(void) alpha;
(void) an;
}
int
main(int argc, char *argv[])
{
struct stream colour, alpha;
void (*process)(char *restrict output, char *restrict cbuf, char *restrict abuf,
struct stream *colour, struct stream *alpha, size_t cn, size_t an);
ARGBEGIN {
default:
usage();
} ARGEND;
if (argc != 1)
usage();
eopen_stream(&colour, NULL);
eopen_stream(&alpha, argv[0]);
if (!strcmp(colour.pixfmt, "xyza"))
process = process_xyza;
else
eprintf("pixel format %s is not supported, try xyza\n", colour.pixfmt);
echeck_compat(&colour, &alpha);
fprint_stream_head(stdout, &colour);
efflush(stdout, "<stdout>");
process_each_frame_two_streams(&colour, &alpha, STDOUT_FILENO, "<stdout>", process);
return 0;
}
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