Add dragon

A demonstration of aligned-path stroking.

3 files changed, 231 insertions, 1 deletions

diff --git a/.gitignore b/.gitignore
index 116f3c0..c7d4f7e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,5 @@
 chart-demo
+dragon-demo
 fish-demo
 flowers-demo
 gears-demo
diff --git a/Makefile b/Makefile
index b172918..2d80825 100644
--- a/Makefile
+++ b/Makefile
@@ -38,7 +38,7 @@ else
 DEFINES+=-DHAVE_COGL=0
 endif
 
-all: spinner-demo spiral-demo slideshow-demo tiger-demo fish-demo flowers-demo gears-demo gradient-demo chart-demo waterfall-demo
+all: spinner-demo spiral-demo slideshow-demo tiger-demo fish-demo flowers-demo gears-demo gradient-demo chart-demo waterfall-demo dragon-demo
 
 ifeq ($(shell pkg-config --exists poppler-glib && echo 1), 1)
 all: poppler-demo
@@ -72,6 +72,8 @@ chart-demo: chart-demo.c $(SOURCES) demo.h Makefile
 	$(CC) $(DEFINES) $(CFLAGS) -o $@ chart-demo.c $(SOURCES) $(LIBS)
 waterfall-demo: waterfall-demo.c $(SOURCES) demo.h list.h Makefile
 	$(CC) $(DEFINES) $(CFLAGS) -o $@ waterfall-demo.c $(SOURCES) $(LIBS)
+dragon-demo: dragon-demo.c $(SOURCES) demo.h list.h Makefile
+	$(CC) $(DEFINES) $(CFLAGS) -o $@ dragon-demo.c $(SOURCES) $(LIBS)
 clean:
 	rm -f *-demo
 
diff --git a/dragon-demo.c b/dragon-demo.c
new file mode 100644
index 0000000..cb31575
--- /dev/null
+++ b/dragon-demo.c
@@ -0,0 +1,227 @@
+/*
+ * Copyright © 2007 Chris Wilson
+ *
+ * Permission to use, copy, modify, distribute, and sell this software
+ * and its documentation for any purpose is hereby granted without
+ * fee, provided that the above copyright notice appear in all copies
+ * and that both that copyright notice and this permission notice
+ * appear in supporting documentation, and that the name of
+ * Chris Wilson not be used in advertising or publicity pertaining to
+ * distribution of the software without specific, written prior
+ * permission. Chris Wilson makes no representations about the
+ * suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * CHRIS WILSON DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL CHRIS WILSON BE LIABLE FOR ANY SPECIAL,
+ * INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
+ * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
+ * IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ * Author: Chris Wilson <chris@chris-wilson.co.uk>
+ *
+ * Inspiration (and path!) taken from
+ * http://labs.trolltech.com/blogs/2007/08/31/rasterizing-dragons/
+ */
+
+#include "demo.h"
+#include <string.h>
+#include <sys/time.h>
+
+#ifndef MIN
+#define MIN(a,b) (((a) < (b)) ? (a) : (b))
+#endif
+
+#ifndef MAX
+#define MAX(a,b) (((a) > (b)) ? (a) : (b))
+#endif
+
+static inline int
+next_pot (int v)
+{
+	v--;
+	v |= v >> 1;
+	v |= v >> 2;
+	v |= v >> 4;
+	v |= v >> 8;
+	v |= v >> 16;
+	v++;
+	return v;
+}
+
+static cairo_bool_t
+direction (int i)
+{
+	int pivot, np2;
+
+	if (i < 2)
+		return TRUE;
+
+	np2 = next_pot (i + 1);
+	if (np2 == i + 1)
+		return TRUE;
+
+	pivot = np2 / 2 - 1;
+	return ! direction (2 * pivot - i);
+}
+
+static void
+path (cairo_t *cr, int step, int dir, int iterations)
+{
+	double dx, dy;
+	int i;
+
+	switch (dir) {
+	default:
+	case 0: dx =  step; dy =  0; break;
+	case 1: dx = -step; dy =  0; break;
+	case 2: dx =  0; dy =  step; break;
+	case 3: dx =  0; dy = -step; break;
+	}
+
+	for (i = 0; i < iterations; i++) {
+		cairo_rel_line_to (cr, dx, dy);
+
+		if (direction (i)) {
+			double t = dx;
+			dx = dy;
+			dy = -t;
+		} else {
+			double t = dx;
+			dx = -dy;
+			dy = t;
+		}
+	}
+}
+
+static void
+dragon (cairo_t *cr, int width, int height, int iterations)
+{
+	double cx, cy;
+
+	cx = .5 * width;
+	cy = .5 * height;
+
+	cairo_set_source_rgb (cr, 0, 0, 0);
+	cairo_paint (cr);
+
+	cairo_set_line_width (cr, 4.);
+
+	cairo_move_to (cr, cx, cy);
+	path (cr, 12, 0, iterations);
+	cairo_set_source_rgb (cr, 1, 0, 0);
+	cairo_stroke(cr);
+
+	cairo_move_to (cr, cx, cy);
+	path (cr, 12, 1, iterations);
+	cairo_set_source_rgb (cr, 0, 1, 0);
+	cairo_stroke(cr);
+
+	cairo_move_to (cr, cx, cy);
+	path (cr, 12, 2, iterations);
+	cairo_set_source_rgb (cr, 0, 0, 1);
+	cairo_stroke(cr);
+
+	cairo_move_to (cr, cx, cy);
+	path (cr, 12, 3, iterations);
+	cairo_set_source_rgb (cr, 1, 1, 1);
+	cairo_stroke(cr);
+}
+
+static int done;
+static void signal_handler(int sig)
+{
+	done = sig;
+}
+
+int main (int argc, char **argv)
+{
+	struct device *device;
+	struct timeval start, last_tty, last_fps, now;
+	int iterations = 1;
+
+	double delta;
+	int frame = 0;
+	int frames = 0;
+	int show_fps = 1;
+	int benchmark;
+	const char *version;
+	enum clip clip;
+
+	int n;
+
+	device = device_open(argc, argv);
+	version = device_show_version(argc, argv);
+	clip = device_get_clip(argc, argv);
+	benchmark = device_get_benchmark(argc, argv);
+	if (benchmark == 0)
+		benchmark = 20;
+	if (benchmark > 0)
+		show_fps = 0;
+
+	signal(SIGHUP, signal_handler);
+
+	for (n = 1; n < argc; n++) {
+		if (strcmp (argv[n], "--hide-fps") == 0)
+			show_fps = 0;
+	}
+
+	gettimeofday(&start, 0); now = last_tty = last_fps = start;
+	do {
+		struct framebuffer *fb = device->get_framebuffer (device);
+		cairo_t *cr = cairo_create(fb->surface);
+
+		dragon(cr, device->width, device->height, iterations);
+		if (++iterations == 4096)
+			iterations = 1;
+
+		gettimeofday(&now, NULL);
+		if (show_fps && last_fps.tv_sec) {
+			fps_draw(cr, device->name, version, &last_fps, &now);
+		}
+		last_fps = now;
+
+		cairo_destroy(cr);
+
+		fb->show (fb);
+		fb->destroy (fb);
+
+		if (benchmark < 0 && 0) {
+			delta = now.tv_sec - last_tty.tv_sec;
+			delta += (now.tv_usec - last_tty.tv_usec)*1e-6;
+			frames++;
+			if (delta >  5) {
+				printf("%.2f fps\n", frames/delta);
+				last_tty = now;
+				frames = 0;
+			}
+		}
+
+		frame++;
+		if (benchmark > 0) {
+			delta = now.tv_sec - start.tv_sec;
+			delta += (now.tv_usec - start.tv_usec)*1e-6;
+			if (delta > benchmark) {
+				printf("dragon: %.2f fps\n", frame / delta);
+				break;
+			}
+		}
+	} while (!done);
+
+	if (benchmark < 0) {
+		struct framebuffer *fb = device->get_framebuffer (device);
+		cairo_t *cr = cairo_create(fb->surface);
+
+		dragon(cr, device->width, device->height, 2048);
+		cairo_destroy(cr);
+
+		fps_finish(fb, device->name, version);
+		fb->show (fb);
+		fb->destroy (fb);
+		pause();
+	}
+
+	return 0;
+}