From 4674ec0e4b833ab0d0365225ba99228df14abe87 Mon Sep 17 00:00:00 2001
From: Mattias Andrée <maandree@kth.se>
Date: Fri, 13 Jan 2017 09:05:08 +0100
Subject: Rename to blind
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Signed-off-by: Mattias Andrée <maandree@kth.se>
---
 src/blind-stack.c | 80 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 80 insertions(+)
 create mode 100644 src/blind-stack.c

(limited to 'src/blind-stack.c')

diff --git a/src/blind-stack.c b/src/blind-stack.c
new file mode 100644
index 0000000..a03fd91
--- /dev/null
+++ b/src/blind-stack.c
@@ -0,0 +1,80 @@
+/* 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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