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/* See LICENSE file for copyright and license details. */
#include "stream.h"
#include "util.h"
#include <fcntl.h>
#include <inttypes.h>
#include <string.h>
#include <unistd.h>
USAGE("[-b] bottom-stream ... top-stream")
#define PROCESS_LINEAR_3CH_ALPHA(TYPE, BLEND)\
do {\
TYPE x1, y1, z1, a1;\
TYPE x2, y2, z2, a2;\
size_t i, j;\
for (i = 0; i < n; i += streams->pixel_size) {\
x1 = ((TYPE *)(streams[0].buf + i))[0];\
y1 = ((TYPE *)(streams[0].buf + i))[1];\
z1 = ((TYPE *)(streams[0].buf + i))[2];\
a1 = ((TYPE *)(streams[0].buf + i))[3];\
for (j = 1; j < n_streams; j++) {\
x2 = ((TYPE *)(streams[j].buf + i))[0];\
y2 = ((TYPE *)(streams[j].buf + i))[1];\
z2 = ((TYPE *)(streams[j].buf + i))[2];\
a2 = ((TYPE *)(streams[j].buf + i))[3];\
if (BLEND)\
a2 /= j + 1;\
x1 = x1 * a1 * (1 - a2) + x2 * a2;\
y1 = y1 * a1 * (1 - a2) + y2 * a2;\
z1 = z1 * a1 * (1 - a2) + z2 * a2;\
a1 = a1 * (1 - a2) + a2;\
}\
((TYPE *)(streams[0].buf + i))[0] = x1;\
((TYPE *)(streams[0].buf + i))[1] = y1;\
((TYPE *)(streams[0].buf + i))[2] = z1;\
((TYPE *)(streams[0].buf + i))[3] = a1;\
}\
} while (0)
static void process_xyza (struct stream *streams, size_t n_streams, size_t n) { PROCESS_LINEAR_3CH_ALPHA(double, 0); }
static void process_xyza_b(struct stream *streams, size_t n_streams, size_t n) { PROCESS_LINEAR_3CH_ALPHA(double, 1); }
int
main(int argc, char *argv[])
{
struct stream *streams;
size_t n_streams, i;
int blend = 0;
void (*process)(struct stream *streams, size_t n_streams, size_t n) = NULL;
ARGBEGIN {
case 'b':
blend = 1;
break;
default:
usage();
} ARGEND;
if (argc < 2)
usage();
n_streams = (size_t)argc;
streams = ecalloc(n_streams, sizeof(*streams));
for (i = 0; i < n_streams; i++) {
streams[i].file = argv[i];
streams[i].fd = eopen(streams[i].file, O_RDONLY);
}
if (!strcmp(streams->pixfmt, "xyza"))
process = blend ? process_xyza_b : process_xyza;
else
eprintf("pixel format %s is not supported, try xyza\n", streams->pixfmt);
process_multiple_streams(streams, n_streams, STDOUT_FILENO, "<stdout>", process);
free(streams);
return 0;
}
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