1 files changed, 134 insertions, 0 deletions
diff --git a/src/blind-spiral-gradient.c b/src/blind-spiral-gradient.c
new file mode 100644
index 0000000..31d9820
--- /dev/null
+++ b/src/blind-spiral-gradient.c
@@ -0,0 +1,134 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+USAGE("[-al] -w width -h height")
+
+static int anticlockwise = 0;
+static int logarithmic = 0;
+static size_t width = 0;
+static size_t height = 0;
+static int with_params;
+
+
+#define PROCESS(TYPE, SUFFIX)\
+	static void\
+	process_##SUFFIX(struct stream *stream)\
+	{\
+		typedef TYPE pixel_t[4];\
+		pixel_t buf[BUFSIZ / sizeof(pixel_t)];\
+		TYPE *params, x1, y1, x2, y2, b, r, u, v;\
+		TYPE x, y, a = 0, e = 1, p = 1, k = 1, ep = 1;\
+		size_t ix, iy, ptr = 0;\
+		for (;;) {\
+			while (stream->ptr < stream->frame_size) {\
+				if (!eread_stream(stream, stream->frame_size - stream->ptr)) {\
+					ewriteall(STDOUT_FILENO, buf, ptr * sizeof(*buf), "<stdout>");\
+					return;\
+				}\
+			}\
+			params = (TYPE *)stream->buf;\
+			x1 = (params)[0];\
+			y1 = (params)[1];\
+			x2 = (params)[4];\
+			y2 = (params)[5];\
+			if (with_params) {\
+				a = (params)[8];\
+				e = (params)[9];\
+				p = (params)[10];\
+				k = (params)[11];\
+				ep = 1 / (e * p);\
+			}\
+			memmove(stream->buf, stream->buf + stream->frame_size,\
+				stream->ptr -= stream->frame_size);\
+			\
+			x2 -= x1;\
+			y2 -= y1;\
+			u = atan2(y2, x2);\
+			b = sqrt(x2 * x2 + y2 * y2);\
+			if (logarithmic)\
+				b = log(b);\
+			b /= pow(2 * (TYPE)M_PI, e);\
+			\
+			for (iy = 0; iy < height; iy++) {\
+				y = (TYPE)iy - y1;\
+				for (ix = 0; ix < width; ix++) {\
+					x = (TYPE)ix - x1;\
+					v = atan2(y, x);\
+					if (anticlockwise)\
+						v = 1 - v;\
+					v -= u;\
+					v += 4 * (TYPE)M_PI;\
+					v = mod(v, 2 * (TYPE)M_PI);\
+					r = sqrt(x * x + y * y);\
+					r -= a;\
+					if (!logarithmic) {\
+						r = pow(r / b, ep);\
+						r = (r - v) / (2 * (TYPE)M_PI);\
+					} else if (r) {\
+						r = log(r / k);\
+						r = pow(r / b, ep);\
+						r = (r - v) / (2 * (TYPE)M_PI);\
+					}\
+					buf[ptr][0] = buf[ptr][1] = buf[ptr][2] = buf[ptr][3] = r;\
+					if (++ptr == ELEMENTSOF(buf)) {\
+						ewriteall(STDOUT_FILENO, buf, sizeof(buf), "<stdout>");\
+						ptr = 0;\
+					}\
+				}\
+			}\
+		}\
+	}
+
+PROCESS(double, lf)
+PROCESS(float, f)
+
+
+int
+main(int argc, char *argv[])
+{
+	struct stream stream;
+	void (*process)(struct stream *stream);
+
+	ARGBEGIN {
+	case 'a':
+		anticlockwise = 1;
+		break;
+	case 'l':
+		logarithmic = 1;
+		break;
+	case 'w':
+		width = etozu_flag('w', UARGF(), 1, SIZE_MAX);
+		break;
+	case 'h':
+		height = etozu_flag('h', UARGF(), 1, SIZE_MAX);
+		break;
+	default:
+		usage();
+	} ARGEND;
+
+	if (!width || !height || argc)
+		usage();
+
+	eopen_stream(&stream, NULL);
+
+	if (!strcmp(stream.pixfmt, "xyza"))
+		process = process_lf;
+	else if (!strcmp(stream.pixfmt, "xyza f"))
+		process = process_f;
+	else
+		eprintf("pixel format %s is not supported, try xyza\n", stream.pixfmt);
+
+	if (stream.width > 3 || stream.height > 3 ||
+	    stream.width * stream.height < 2 ||
+	    stream.width * stream.height > 3)
+		eprintf("<stdin>: each frame must contain exactly 2 or 3 pixels\n");
+
+	with_params = stream.width * stream.height == 3;
+
+	stream.width = width;
+	stream.height = height;
+	fprint_stream_head(stdout, &stream);
+	efflush(stdout, "<stdout>");
+	process(&stream);
+	return 0;
+}