Original 5.40

1 files changed, 986 insertions, 0 deletions

diff --git a/hacks/compass.c b/hacks/compass.c
new file mode 100644
index 0000000..1dc1d3e
--- /dev/null
+++ b/hacks/compass.c
@@ -0,0 +1,986 @@
+/* xscreensaver, Copyright (c) 1999-2018 Jamie Zawinski <jwz@jwz.org>
+ *
+ * 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.  No representations are made about the suitability of this
+ * software for any purpose.  It is provided "as is" without express or 
+ * implied warranty.
+ */
+
+#include <math.h>
+#include "screenhack.h"
+
+#ifdef HAVE_DOUBLE_BUFFER_EXTENSION
+# include "xdbe.h"
+#endif /* HAVE_DOUBLE_BUFFER_EXTENSION */
+
+#define countof(x) (sizeof(x)/sizeof(*(x)))
+#define ABS(x) ((x)<0?-(x):(x))
+#define MAX(x,y) ((x)<(y)?(y):(x))
+#define MIN(x,y) ((x)>(y)?(y):(x))
+#define RAND(n) ((long) ((random() & 0x7fffffff) % ((long) (n))))
+#define RANDSIGN() ((random() & 1) ? 1 : -1)
+
+struct state {
+  Display *dpy;
+  Window window;
+
+  int delay;
+  Bool dbuf;
+  struct disc *discs[4];
+  int x, y, size, size2;
+  GC ptr_gc;
+  GC erase_gc;
+  XWindowAttributes xgwa;
+  Pixmap b, ba, bb;	/* double-buffer to reduce flicker */
+#ifdef HAVE_DOUBLE_BUFFER_EXTENSION
+  XdbeBackBuffer backb;
+#endif /* HAVE_DOUBLE_BUFFER_EXTENSION */
+};
+
+
+
+struct disc {
+  int theta;		/* 0 - 360*64 */
+  int velocity;
+  int acceleration;
+  int limit;
+  GC gc;
+  void (*draw) (struct state *, Drawable, struct disc *,
+                int x, int y, int radius);
+};
+
+
+static void
+draw_letters (struct state *st, Drawable d, struct disc *disc,
+              int x, int y, int radius)
+{
+  XPoint points[50];
+  double th2 = 2 * M_PI * (disc->theta / ((double) 360*64));
+  double th;
+
+  /* W */
+
+  th = th2;
+
+  points[0].x = x + radius * 0.8 * cos(th - 0.07);
+  points[0].y = y + radius * 0.8 * sin(th - 0.07);
+
+  points[1].x = x + radius * 0.7 * cos(th - 0.05);
+  points[1].y = y + radius * 0.7 * sin(th - 0.05);
+
+  points[2].x = x + radius * 0.78 * cos(th);
+  points[2].y = y + radius * 0.78 * sin(th);
+
+  points[3].x = x + radius * 0.7 * cos(th + 0.05);
+  points[3].y = y + radius * 0.7 * sin(th + 0.05);
+
+  points[4].x = x + radius * 0.8 * cos(th + 0.07);
+  points[4].y = y + radius * 0.8 * sin(th + 0.07);
+
+  XDrawLines (st->dpy, d, disc->gc, points, 5, CoordModeOrigin);
+
+  /* 30 (1) */
+
+  th = th2 + (2 * M_PI * 0.08333);
+
+  points[0].x = x + radius * 0.78 * cos(th - 0.13);
+  points[0].y = y + radius * 0.78 * sin(th - 0.13);
+
+  points[1].x = x + radius * 0.8  * cos(th - 0.08);
+  points[1].y = y + radius * 0.8  * sin(th - 0.08);
+
+  points[2].x = x + radius * 0.78 * cos(th - 0.03);
+  points[2].y = y + radius * 0.78 * sin(th - 0.03);
+
+  points[3].x = x + radius * 0.76 * cos(th - 0.03);
+  points[3].y = y + radius * 0.76 * sin(th - 0.03);
+
+  points[4].x = x + radius * 0.75 * cos(th - 0.08);
+  points[4].y = y + radius * 0.75 * sin(th - 0.08);
+
+  points[5].x = x + radius * 0.74 * cos(th - 0.03);
+  points[5].y = y + radius * 0.74 * sin(th - 0.03);
+
+  points[6].x = x + radius * 0.72 * cos(th - 0.03);
+  points[6].y = y + radius * 0.72 * sin(th - 0.03);
+
+  points[7].x = x + radius * 0.7  * cos(th - 0.08);
+  points[7].y = y + radius * 0.7  * sin(th - 0.08);
+
+  points[8].x = x + radius * 0.72  * cos(th - 0.13);
+  points[8].y = y + radius * 0.72  * sin(th - 0.13);
+
+  XDrawLines (st->dpy, d, disc->gc, points, 9, CoordModeOrigin);
+
+  /* 30 (2) */
+
+  points[0].x = x + radius * 0.78 * cos(th + 0.03);
+  points[0].y = y + radius * 0.78 * sin(th + 0.03);
+
+  points[1].x = x + radius * 0.8  * cos(th + 0.08);
+  points[1].y = y + radius * 0.8  * sin(th + 0.08);
+
+  points[2].x = x + radius * 0.78 * cos(th + 0.13);
+  points[2].y = y + radius * 0.78 * sin(th + 0.13);
+
+  points[3].x = x + radius * 0.72 * cos(th + 0.13);
+  points[3].y = y + radius * 0.72 * sin(th + 0.13);
+
+  points[4].x = x + radius * 0.7  * cos(th + 0.08);
+  points[4].y = y + radius * 0.7  * sin(th + 0.08);
+
+  points[5].x = x + radius * 0.72  * cos(th + 0.03);
+  points[5].y = y + radius * 0.72  * sin(th + 0.03);
+
+  points[6] = points[0];
+
+  XDrawLines (st->dpy, d, disc->gc, points, 7, CoordModeOrigin);
+
+  /* 33 (1) */
+
+  th = th2 + (2 * M_PI * 0.16666);
+
+  points[0].x = x + radius * 0.78 * cos(th - 0.13);
+  points[0].y = y + radius * 0.78 * sin(th - 0.13);
+
+  points[1].x = x + radius * 0.8  * cos(th - 0.08);
+  points[1].y = y + radius * 0.8  * sin(th - 0.08);
+
+  points[2].x = x + radius * 0.78 * cos(th - 0.03);
+  points[2].y = y + radius * 0.78 * sin(th - 0.03);
+
+  points[3].x = x + radius * 0.76 * cos(th - 0.03);
+  points[3].y = y + radius * 0.76 * sin(th - 0.03);
+
+  points[4].x = x + radius * 0.75 * cos(th - 0.08);
+  points[4].y = y + radius * 0.75 * sin(th - 0.08);
+
+  points[5].x = x + radius * 0.74 * cos(th - 0.03);
+  points[5].y = y + radius * 0.74 * sin(th - 0.03);
+
+  points[6].x = x + radius * 0.72 * cos(th - 0.03);
+  points[6].y = y + radius * 0.72 * sin(th - 0.03);
+
+  points[7].x = x + radius * 0.7  * cos(th - 0.08);
+  points[7].y = y + radius * 0.7  * sin(th - 0.08);
+
+  points[8].x = x + radius * 0.72  * cos(th - 0.13);
+  points[8].y = y + radius * 0.72  * sin(th - 0.13);
+
+  XDrawLines (st->dpy, d, disc->gc, points, 9, CoordModeOrigin);
+
+  /* 33 (2) */
+
+  points[0].x = x + radius * 0.78 * cos(th + 0.03);
+  points[0].y = y + radius * 0.78 * sin(th + 0.03);
+
+  points[1].x = x + radius * 0.8  * cos(th + 0.08);
+  points[1].y = y + radius * 0.8  * sin(th + 0.08);
+
+  points[2].x = x + radius * 0.78 * cos(th + 0.13);
+  points[2].y = y + radius * 0.78 * sin(th + 0.13);
+
+  points[3].x = x + radius * 0.76 * cos(th + 0.13);
+  points[3].y = y + radius * 0.76 * sin(th + 0.13);
+
+  points[4].x = x + radius * 0.75 * cos(th + 0.08);
+  points[4].y = y + radius * 0.75 * sin(th + 0.08);
+
+  points[5].x = x + radius * 0.74 * cos(th + 0.13);
+  points[5].y = y + radius * 0.74 * sin(th + 0.13);
+
+  points[6].x = x + radius * 0.72 * cos(th + 0.13);
+  points[6].y = y + radius * 0.72 * sin(th + 0.13);
+
+  points[7].x = x + radius * 0.7  * cos(th + 0.08);
+  points[7].y = y + radius * 0.7  * sin(th + 0.08);
+
+  points[8].x = x + radius * 0.72  * cos(th + 0.03);
+  points[8].y = y + radius * 0.72  * sin(th + 0.03);
+
+  XDrawLines (st->dpy, d, disc->gc, points, 9, CoordModeOrigin);
+
+  /* N */
+
+  th = th2 + (2 * M_PI * 0.25);
+
+  points[0].x = x + radius * 0.7 * cos(th - 0.05);
+  points[0].y = y + radius * 0.7 * sin(th - 0.05);
+
+  points[1].x = x + radius * 0.8 * cos(th - 0.05);
+  points[1].y = y + radius * 0.8 * sin(th - 0.05);
+
+  points[2].x = x + radius * 0.7 * cos(th + 0.05);
+  points[2].y = y + radius * 0.7 * sin(th + 0.05);
+
+  points[3].x = x + radius * 0.8 * cos(th + 0.05);
+  points[3].y = y + radius * 0.8 * sin(th + 0.05);
+
+  XDrawLines (st->dpy, d, disc->gc, points, 4, CoordModeOrigin);
+
+  /* 3 */
+
+  th = th2 + (2 * M_PI * 0.33333);
+
+  points[0].x = x + radius * 0.78 * cos(th - 0.05);
+  points[0].y = y + radius * 0.78 * sin(th - 0.05);
+
+  points[1].x = x + radius * 0.8  * cos(th);
+  points[1].y = y + radius * 0.8  * sin(th);
+
+  points[2].x = x + radius * 0.78 * cos(th + 0.05);
+  points[2].y = y + radius * 0.78 * sin(th + 0.05);
+
+  points[3].x = x + radius * 0.76 * cos(th + 0.05);
+  points[3].y = y + radius * 0.76 * sin(th + 0.05);
+
+  points[4].x = x + radius * 0.75 * cos(th);
+  points[4].y = y + radius * 0.75 * sin(th);
+
+  points[5].x = x + radius * 0.74 * cos(th + 0.05);
+  points[5].y = y + radius * 0.74 * sin(th + 0.05);
+
+  points[6].x = x + radius * 0.72 * cos(th + 0.05);
+  points[6].y = y + radius * 0.72 * sin(th + 0.05);
+
+  points[7].x = x + radius * 0.7  * cos(th);
+  points[7].y = y + radius * 0.7  * sin(th);
+
+  points[8].x = x + radius * 0.72  * cos(th - 0.05);
+  points[8].y = y + radius * 0.72  * sin(th - 0.05);
+
+  XDrawLines (st->dpy, d, disc->gc, points, 9, CoordModeOrigin);
+
+  /* 6 */
+
+  th = th2 + (2 * M_PI * 0.41666);
+
+  points[0].x = x + radius * 0.78 * cos(th + 0.05);
+  points[0].y = y + radius * 0.78 * sin(th + 0.05);
+
+  points[1].x = x + radius * 0.8  * cos(th);
+  points[1].y = y + radius * 0.8  * sin(th);
+
+  points[2].x = x + radius * 0.78 * cos(th - 0.05);
+  points[2].y = y + radius * 0.78 * sin(th - 0.05);
+
+  points[3].x = x + radius * 0.72 * cos(th - 0.05);
+  points[3].y = y + radius * 0.72 * sin(th - 0.05);
+
+  points[4].x = x + radius * 0.7  * cos(th);
+  points[4].y = y + radius * 0.7  * sin(th);
+
+  points[5].x = x + radius * 0.72 * cos(th + 0.05);
+  points[5].y = y + radius * 0.72 * sin(th + 0.05);
+
+  points[6].x = x + radius * 0.74 * cos(th + 0.05);
+  points[6].y = y + radius * 0.74 * sin(th + 0.05);
+
+  points[7].x = x + radius * 0.76 * cos(th);
+  points[7].y = y + radius * 0.76 * sin(th);
+
+  points[8].x = x + radius * 0.74 * cos(th - 0.05);
+  points[8].y = y + radius * 0.74 * sin(th - 0.05);
+
+  XDrawLines (st->dpy, d, disc->gc, points, 9, CoordModeOrigin);
+
+
+  /* E */
+
+  th = th2 + (2 * M_PI * 0.5);
+
+  points[0].x = x + radius * 0.8 * cos(th + 0.05);
+  points[0].y = y + radius * 0.8 * sin(th + 0.05);
+
+  points[1].x = x + radius * 0.8 * cos(th - 0.05);
+  points[1].y = y + radius * 0.8 * sin(th - 0.05);
+
+  points[2].x = x + radius * 0.75 * cos(th - 0.05);
+  points[2].y = y + radius * 0.75 * sin(th - 0.05);
+
+  points[3].x = x + radius * 0.75 * cos(th + 0.025);
+  points[3].y = y + radius * 0.75 * sin(th + 0.025);
+
+  points[4].x = x + radius * 0.75 * cos(th - 0.05);
+  points[4].y = y + radius * 0.75 * sin(th - 0.05);
+
+  points[5].x = x + radius * 0.7 * cos(th - 0.05);
+  points[5].y = y + radius * 0.7 * sin(th - 0.05);
+
+  points[6].x = x + radius * 0.7 * cos(th + 0.05);
+  points[6].y = y + radius * 0.7 * sin(th + 0.05);
+
+  XDrawLines (st->dpy, d, disc->gc, points, 7, CoordModeOrigin);
+
+  /* 12 (1) */
+
+  th = th2 + (2 * M_PI * 0.58333);
+
+  points[0].x = x + radius * 0.77 * cos(th - 0.06);
+  points[0].y = y + radius * 0.77 * sin(th - 0.06);
+
+  points[1].x = x + radius * 0.8  * cos(th - 0.03);
+  points[1].y = y + radius * 0.8  * sin(th - 0.03);
+
+  points[2].x = x + radius * 0.7  * cos(th - 0.03);
+  points[2].y = y + radius * 0.7  * sin(th - 0.03);
+
+  XDrawLines (st->dpy, d, disc->gc, points, 3, CoordModeOrigin);
+
+  /* 12 (2) */
+
+  points[0].x = x + radius * 0.78 * cos(th + 0.02);
+  points[0].y = y + radius * 0.78 * sin(th + 0.02);
+
+  points[1].x = x + radius * 0.8  * cos(th + 0.07);
+  points[1].y = y + radius * 0.8  * sin(th + 0.07);
+
+  points[2].x = x + radius * 0.78 * cos(th + 0.11);
+  points[2].y = y + radius * 0.78 * sin(th + 0.11);
+
+  points[3].x = x + radius * 0.76 * cos(th + 0.11);
+  points[3].y = y + radius * 0.76 * sin(th + 0.11);
+
+  points[4].x = x + radius * 0.74 * cos(th + 0.02);
+  points[4].y = y + radius * 0.74 * sin(th + 0.02);
+
+  points[5].x = x + radius * 0.71 * cos(th + 0.03);
+  points[5].y = y + radius * 0.71 * sin(th + 0.03);
+
+  points[6].x = x + radius * 0.7  * cos(th + 0.03);
+  points[6].y = y + radius * 0.7  * sin(th + 0.03);
+
+  points[7].x = x + radius * 0.7  * cos(th + 0.13);
+  points[7].y = y + radius * 0.7  * sin(th + 0.13);
+
+  XDrawLines (st->dpy, d, disc->gc, points, 8, CoordModeOrigin);
+
+  /* 15 (1) */
+
+  th = th2 + (2 * M_PI * 0.66666);
+
+  points[0].x = x + radius * 0.77 * cos(th - 0.06);
+  points[0].y = y + radius * 0.77 * sin(th - 0.06);
+
+  points[1].x = x + radius * 0.8  * cos(th - 0.03);
+  points[1].y = y + radius * 0.8  * sin(th - 0.03);
+
+  points[2].x = x + radius * 0.7  * cos(th - 0.03);
+  points[2].y = y + radius * 0.7  * sin(th - 0.03);
+
+  XDrawLines (st->dpy, d, disc->gc, points, 3, CoordModeOrigin);
+
+  /* 15 (2) */
+
+  points[0].x = x + radius * 0.8  * cos(th + 0.11);
+  points[0].y = y + radius * 0.8  * sin(th + 0.11);
+
+  points[1].x = x + radius * 0.8  * cos(th + 0.02);
+  points[1].y = y + radius * 0.8  * sin(th + 0.02);
+
+  points[2].x = x + radius * 0.76 * cos(th + 0.02);
+  points[2].y = y + radius * 0.76 * sin(th + 0.02);
+
+  points[3].x = x + radius * 0.77 * cos(th + 0.06);
+  points[3].y = y + radius * 0.77 * sin(th + 0.06);
+
+  points[4].x = x + radius * 0.76 * cos(th + 0.10);
+  points[4].y = y + radius * 0.76 * sin(th + 0.10);
+
+  points[5].x = x + radius * 0.73 * cos(th + 0.11);
+  points[5].y = y + radius * 0.73 * sin(th + 0.11);
+
+  points[6].x = x + radius * 0.72 * cos(th + 0.10);
+  points[6].y = y + radius * 0.72 * sin(th + 0.10);
+
+  points[7].x = x + radius * 0.7  * cos(th + 0.06);
+  points[7].y = y + radius * 0.7  * sin(th + 0.06);
+
+  points[8].x = x + radius * 0.72 * cos(th + 0.02);
+  points[8].y = y + radius * 0.72 * sin(th + 0.02);
+
+  XDrawLines (st->dpy, d, disc->gc, points, 9, CoordModeOrigin);
+
+  /* S */
+
+  th = th2 + (2 * M_PI * 0.75);
+
+  points[0].x = x + radius * 0.78 * cos(th + 0.05);
+  points[0].y = y + radius * 0.78 * sin(th + 0.05);
+
+  points[1].x = x + radius * 0.8  * cos(th);
+  points[1].y = y + radius * 0.8  * sin(th);
+
+  points[2].x = x + radius * 0.78 * cos(th - 0.05);
+  points[2].y = y + radius * 0.78 * sin(th - 0.05);
+
+  points[3].x = x + radius * 0.76 * cos(th - 0.05);
+  points[3].y = y + radius * 0.76 * sin(th - 0.05);
+
+  points[4].x = x + radius * 0.74 * cos(th + 0.05);
+  points[4].y = y + radius * 0.74 * sin(th + 0.05);
+
+  points[5].x = x + radius * 0.72 * cos(th + 0.05);
+  points[5].y = y + radius * 0.72 * sin(th + 0.05);
+
+  points[6].x = x + radius * 0.7  * cos(th);
+  points[6].y = y + radius * 0.7  * sin(th);
+
+  points[7].x = x + radius * 0.72  * cos(th - 0.05);
+  points[7].y = y + radius * 0.72  * sin(th - 0.05);
+
+  XDrawLines (st->dpy, d, disc->gc, points, 8, CoordModeOrigin);
+
+  /* 21 (1) */
+
+  th = th2 + (2 * M_PI * 0.83333);
+
+  points[0].x = x + radius * 0.78 * cos(th - 0.13);
+  points[0].y = y + radius * 0.78 * sin(th - 0.13);
+
+  points[1].x = x + radius * 0.8  * cos(th - 0.08);
+  points[1].y = y + radius * 0.8  * sin(th - 0.08);
+
+  points[2].x = x + radius * 0.78 * cos(th - 0.03);
+  points[2].y = y + radius * 0.78 * sin(th - 0.03);
+
+  points[3].x = x + radius * 0.76 * cos(th - 0.03);
+  points[3].y = y + radius * 0.76 * sin(th - 0.03);
+
+  points[4].x = x + radius * 0.74 * cos(th - 0.12);
+  points[4].y = y + radius * 0.74 * sin(th - 0.12);
+
+  points[5].x = x + radius * 0.71 * cos(th - 0.13);
+  points[5].y = y + radius * 0.71 * sin(th - 0.13);
+
+  points[6].x = x + radius * 0.7  * cos(th - 0.13);
+  points[6].y = y + radius * 0.7  * sin(th - 0.13);
+
+  points[7].x = x + radius * 0.7  * cos(th - 0.02);
+  points[7].y = y + radius * 0.7  * sin(th - 0.02);
+
+  XDrawLines (st->dpy, d, disc->gc, points, 8, CoordModeOrigin);
+
+  /* 21 (2) */
+
+  points[0].x = x + radius * 0.77 * cos(th + 0.03);
+  points[0].y = y + radius * 0.77 * sin(th + 0.03);
+
+  points[1].x = x + radius * 0.8  * cos(th + 0.06);
+  points[1].y = y + radius * 0.8  * sin(th + 0.06);
+
+  points[2].x = x + radius * 0.7  * cos(th + 0.06);
+  points[2].y = y + radius * 0.7  * sin(th + 0.06);
+
+  XDrawLines (st->dpy, d, disc->gc, points, 3, CoordModeOrigin);
+
+  /* 24 (1) */
+
+  th = th2 + (2 * M_PI * 0.91666);
+
+  points[0].x = x + radius * 0.78 * cos(th - 0.13);
+  points[0].y = y + radius * 0.78 * sin(th - 0.13);
+
+  points[1].x = x + radius * 0.8  * cos(th - 0.08);
+  points[1].y = y + radius * 0.8  * sin(th - 0.08);
+
+  points[2].x = x + radius * 0.78 * cos(th - 0.03);
+  points[2].y = y + radius * 0.78 * sin(th - 0.03);
+
+  points[3].x = x + radius * 0.76 * cos(th - 0.03);
+  points[3].y = y + radius * 0.76 * sin(th - 0.03);
+
+  points[4].x = x + radius * 0.74 * cos(th - 0.12);
+  points[4].y = y + radius * 0.74 * sin(th - 0.12);
+
+  points[5].x = x + radius * 0.71 * cos(th - 0.13);
+  points[5].y = y + radius * 0.71 * sin(th - 0.13);
+
+  points[6].x = x + radius * 0.7  * cos(th - 0.13);
+  points[6].y = y + radius * 0.7  * sin(th - 0.13);
+
+  points[7].x = x + radius * 0.7  * cos(th - 0.02);
+  points[7].y = y + radius * 0.7  * sin(th - 0.02);
+
+  XDrawLines (st->dpy, d, disc->gc, points, 8, CoordModeOrigin);
+
+  /* 24 (2) */
+
+  points[0].x = x + radius * 0.69 * cos(th + 0.09);
+  points[0].y = y + radius * 0.69 * sin(th + 0.09);
+
+  points[1].x = x + radius * 0.8  * cos(th + 0.09);
+  points[1].y = y + radius * 0.8  * sin(th + 0.09);
+
+  points[2].x = x + radius * 0.72 * cos(th + 0.01);
+  points[2].y = y + radius * 0.72 * sin(th + 0.01);
+
+  points[3].x = x + radius * 0.72 * cos(th + 0.13);
+  points[3].y = y + radius * 0.72 * sin(th + 0.13);
+
+  XDrawLines (st->dpy, d, disc->gc, points, 4, CoordModeOrigin);
+}
+
+
+static void
+draw_ticks (struct state *st, Drawable d, struct disc *disc,
+            int x, int y, int radius)
+{
+  XSegment segs[72];
+  int i;
+  double tick = (M_PI * 2) / 72;
+
+  for (i = 0; i < 72; i++)
+    {
+      int radius2 = radius;
+      double th = (i * tick) + (2 * M_PI * (disc->theta / ((double) 360*64)));
+
+      if (i % 6)
+        radius2 -= radius / 16;
+      else
+        radius2 -= radius / 8;
+
+      segs[i].x1 = x + radius  * cos(th);
+      segs[i].y1 = y + radius  * sin(th);
+      segs[i].x2 = x + radius2 * cos(th);
+      segs[i].y2 = y + radius2 * sin(th);
+    }
+  XDrawSegments (st->dpy, d, disc->gc, segs, countof(segs));
+
+  draw_letters (st, d, disc, x, y, radius);
+}
+
+
+static void
+draw_thin_arrow (struct state *st, Drawable d, struct disc *disc,
+                 int x, int y, int radius)
+{
+  XPoint points[3];
+  double th;
+  int radius2;
+  double tick = ((M_PI * 2) / 72) * 2;
+
+  radius *= 0.9;
+  radius2 = radius - (radius / 8) * 3;
+
+  th = 2 * M_PI * (disc->theta / ((double) 360*64));
+
+  points[0].x = x + radius * cos(th);		/* tip */
+  points[0].y = y + radius * sin(th);
+
+  points[1].x = x + radius2 * cos(th - tick);	/* tip left */
+  points[1].y = y + radius2 * sin(th - tick);
+
+  points[2].x = x + radius2 * cos(th + tick);	/* tip right */
+  points[2].y = y + radius2 * sin(th + tick);
+
+  XDrawLine (st->dpy, d, disc->gc,
+             (int) (x + radius2 * cos(th)),
+             (int) (y + radius2 * sin(th)),
+             (int) (x + -radius * cos(th)),
+             (int) (y + -radius * sin(th)));
+
+  XFillPolygon (st->dpy, d, disc->gc, points, 3, Convex, CoordModeOrigin);
+}
+
+
+static void
+draw_thick_arrow (struct state *st, Drawable d, struct disc *disc,
+                  int x, int y, int radius)
+{
+  XPoint points[10];
+  double th;
+  int radius2, radius3;
+  double tick = ((M_PI * 2) / 72) * 2;
+
+  radius *= 0.9;
+  radius2 = radius - (radius / 8) * 3;
+  radius3 = radius - (radius / 8) * 2;
+  th = 2 * M_PI * (disc->theta / ((double) 360*64));
+
+  points[0].x = x + radius * cos(th);		/* tip */
+  points[0].y = y + radius * sin(th);
+
+  points[1].x = x + radius2 * cos(th - tick);	/* tip left */
+  points[1].y = y + radius2 * sin(th - tick);
+
+  points[2].x = x + radius2 * cos(th + tick);	/* tip right */
+  points[2].y = y + radius2 * sin(th + tick);
+
+  points[3] = points[0];
+
+  XDrawLines (st->dpy, d, disc->gc, points, 4, CoordModeOrigin);
+
+  points[0].x = x + radius2 * cos(th - tick/2);	 /* top left */
+  points[0].y = y + radius2 * sin(th - tick/2);
+
+  points[1].x = x + -radius2 * cos(th + tick/2); /* bottom left */
+  points[1].y = y + -radius2 * sin(th + tick/2);
+
+  points[2].x = x + -radius3 * cos(th);		 /* bottom */
+  points[2].y = y + -radius3 * sin(th);
+
+  points[3].x = x + -radius * cos(th);		 /* bottom spike */
+  points[3].y = y + -radius * sin(th);
+
+  points[4] = points[2];			 /* return */
+
+  points[5].x = x + -radius2 * cos(th - tick/2); /* bottom right */
+  points[5].y = y + -radius2 * sin(th - tick/2);
+
+  points[6].x = x + radius2 * cos(th + tick/2);  /* top right */
+  points[6].y = y + radius2 * sin(th + tick/2);
+
+  XDrawLines (st->dpy, d, disc->gc, points, 7, CoordModeOrigin);
+}
+
+
+
+static void
+roll_disc (struct disc *disc)
+{
+  double th = disc->theta;
+  if (th < 0)
+    th = -(th + disc->velocity);
+  else
+    th = (th + disc->velocity);
+
+  if (th > (360*64))
+    th -= (360*64);
+  else if (th < 0)
+    th += (360*64);
+
+  disc->theta = (disc->theta > 0 ? th : -th);
+
+  disc->velocity += disc->acceleration;
+
+  if (disc->velocity > disc->limit || 
+      disc->velocity < -disc->limit)
+    disc->acceleration = -disc->acceleration;
+
+  /* Alter direction of rotational acceleration randomly. */
+  if (! (random() % 120))
+    disc->acceleration = -disc->acceleration;
+
+  /* Change acceleration very occasionally. */
+  if (! (random() % 200))
+    {
+      if (random() & 1)
+	disc->acceleration *= 1.2;
+      else
+	disc->acceleration *= 0.8;
+    }
+}
+
+
+static void
+init_spin (struct disc *disc)
+{
+  disc->limit = 5*64;
+  disc->theta = RAND(360*64);
+  disc->velocity = RAND(16) * RANDSIGN();
+  disc->acceleration = RAND(16) * RANDSIGN();
+}
+
+
+static void
+draw_compass (struct state *st)
+{
+  int i = 0;
+  while (st->discs[i])
+    {
+      st->discs[i]->draw (st, st->b, st->discs[i], st->x, st->y, st->size);
+      roll_disc (st->discs[i]);
+      i++;
+    }
+}
+
+static void
+draw_pointer (struct state *st)
+{
+  int radius = st->size;
+  GC dot_gc = st->discs[0]->gc;
+  XPoint points[3];
+  int size = radius * 0.1;
+
+  /* top */
+
+  points[0].x = st->x - size;
+  points[0].y = st->y - radius - size;
+
+  points[1].x = st->x + size;
+  points[1].y = st->y - radius - size;
+
+  points[2].x = st->x;
+  points[2].y = st->y - radius;
+  
+  XFillPolygon (st->dpy, st->b, st->ptr_gc, points, 3, Convex, CoordModeOrigin);
+
+  /* top right */
+
+  points[0].x = st->x - (radius * 0.85);
+  points[0].y = st->y - (radius * 0.8);
+
+  points[1].x = st->x - (radius * 1.1);
+  points[1].y = st->y - (radius * 0.55);
+
+  points[2].x = st->x - (radius * 0.6);
+  points[2].y = st->y - (radius * 0.65);
+  
+  XFillPolygon (st->dpy, st->b, st->ptr_gc, points, 3, Convex, CoordModeOrigin);
+
+  /* left */
+
+  points[0].x = st->x - (radius * 1.05);
+  points[0].y = st->y;
+
+  points[1].x = st->x - (radius * 1.1);
+  points[1].y = st->y - (radius * 0.025);
+
+  points[2].x = st->x - (radius * 1.1);
+  points[2].y = st->y + (radius * 0.025);
+  
+  XFillPolygon (st->dpy, st->b, dot_gc, points, 3, Convex, CoordModeOrigin);
+
+  /* right */
+
+  points[0].x = st->x + (radius * 1.05);
+  points[0].y = st->y;
+
+  points[1].x = st->x + (radius * 1.1);
+  points[1].y = st->y - (radius * 0.025);
+
+  points[2].x = st->x + (radius * 1.1);
+  points[2].y = st->y + (radius * 0.025);
+  
+  XFillPolygon (st->dpy, st->b, dot_gc, points, 3, Convex, CoordModeOrigin);
+
+  /* bottom */
+
+  points[0].x = st->x;
+  points[0].y = st->y + (radius * 1.05);
+
+  points[1].x = st->x - (radius * 0.025);
+  points[1].y = st->y + (radius * 1.1);
+
+  points[2].x = st->x + (radius * 0.025);
+  points[2].y = st->y + (radius * 1.1);
+  
+  XFillPolygon (st->dpy, st->b, dot_gc, points, 3, Convex, CoordModeOrigin);
+
+  /* bottom left */
+
+  points[0].x = st->x + (radius * 0.74);
+  points[0].y = st->y + (radius * 0.74);
+
+  points[1].x = st->x + (radius * 0.78);
+  points[1].y = st->y + (radius * 0.75);
+
+  points[2].x = st->x + (radius * 0.75);
+  points[2].y = st->y + (radius * 0.78);
+  
+  XFillPolygon (st->dpy, st->b, dot_gc, points, 3, Convex, CoordModeOrigin);
+
+  /* top left */
+
+  points[0].x = st->x + (radius * 0.74);
+  points[0].y = st->y - (radius * 0.74);
+
+  points[1].x = st->x + (radius * 0.78);
+  points[1].y = st->y - (radius * 0.75);
+
+  points[2].x = st->x + (radius * 0.75);
+  points[2].y = st->y - (radius * 0.78);
+  
+  XFillPolygon (st->dpy, st->b, dot_gc, points, 3, Convex, CoordModeOrigin);
+
+  /* bottom right */
+
+  points[0].x = st->x - (radius * 0.74);
+  points[0].y = st->y + (radius * 0.74);
+
+  points[1].x = st->x - (radius * 0.78);
+  points[1].y = st->y + (radius * 0.75);
+
+  points[2].x = st->x - (radius * 0.75);
+  points[2].y = st->y + (radius * 0.78);
+  
+  XFillPolygon (st->dpy, st->b, dot_gc, points, 3, Convex, CoordModeOrigin);
+}
+
+
+static void *
+compass_init (Display *dpy, Window window)
+{
+  struct state *st = (struct state *) calloc (1, sizeof(*st));
+  XGCValues gcv;
+  st->dpy = dpy;
+  st->window = window;
+  st->delay = get_integer_resource (st->dpy, "delay", "Integer");
+  st->dbuf = get_boolean_resource (st->dpy, "doubleBuffer", "Boolean");
+
+# ifdef HAVE_JWXYZ	/* Don't second-guess Quartz's double-buffering */
+  st->dbuf = False;
+# endif
+
+  XGetWindowAttributes (st->dpy, st->window, &st->xgwa);
+  st->size2 = MIN(st->xgwa.width, st->xgwa.height);
+
+  if (st->xgwa.width > st->xgwa.height * 5 ||  /* goofy aspect ratio */
+      st->xgwa.height > st->xgwa.width * 5)
+    st->size2 = MAX(st->xgwa.width, st->xgwa.height);
+
+  {
+    int max = 600;
+    if (st->xgwa.width > 2560) max *= 2;  /* Retina displays */
+    if (st->size2 > max) st->size2 = max;
+  }
+
+  st->size = (st->size2 / 2) * 0.8;
+
+  st->x = st->xgwa.width/2;
+  st->y = st->xgwa.height/2;
+
+  if (st->dbuf)
+    {
+#ifdef HAVE_DOUBLE_BUFFER_EXTENSION
+      st->b = st->backb = xdbe_get_backbuffer (st->dpy, st->window, XdbeUndefined);
+#endif /* HAVE_DOUBLE_BUFFER_EXTENSION */
+
+      if (!st->b)
+        {
+          st->x = st->size2/2;
+          st->y = st->size2/2;
+          st->ba = XCreatePixmap (st->dpy, st->window, st->size2, st->size2, st->xgwa.depth);
+          st->bb = XCreatePixmap (st->dpy, st->window, st->size2, st->size2, st->xgwa.depth);
+          st->b = st->ba;
+        }
+    }
+  else
+    {
+      st->b = st->window;
+    }
+
+  st->discs[0] = (struct disc *) calloc (1, sizeof (struct disc));
+  st->discs[1] = (struct disc *) calloc (1, sizeof (struct disc));
+  st->discs[2] = (struct disc *) calloc (1, sizeof (struct disc));
+  st->discs[3] = 0;
+
+  gcv.foreground = get_pixel_resource (st->dpy, st->xgwa.colormap,
+                                       "foreground", "Foreground");
+  gcv.line_width = MAX(2, (st->size/60));
+  gcv.join_style = JoinBevel;
+  st->discs[0]->draw = draw_ticks;
+  st->discs[0]->gc = XCreateGC (st->dpy, st->b, GCForeground|GCLineWidth|GCJoinStyle,
+                            &gcv);
+  init_spin (st->discs[0]);
+
+  gcv.foreground = get_pixel_resource (st->dpy, st->xgwa.colormap,
+                                       "arrow2Foreground", "Foreground");
+  gcv.line_width = MAX(4, (st->size / 30));
+  st->discs[1]->draw = draw_thick_arrow;
+  st->discs[1]->gc = XCreateGC (st->dpy, st->b, GCForeground|GCLineWidth, &gcv);
+  init_spin (st->discs[1]);
+
+  gcv.foreground = get_pixel_resource (st->dpy, st->xgwa.colormap,
+                                       "arrow1Foreground", "Foreground");
+  gcv.line_width = MAX(4, (st->size / 30));
+  st->discs[2]->draw = draw_thin_arrow;
+  st->discs[2]->gc = XCreateGC (st->dpy, st->b, GCForeground|GCLineWidth, &gcv);
+  init_spin (st->discs[2]);
+
+  gcv.foreground = get_pixel_resource (st->dpy, st->xgwa.colormap,
+                                       "pointerForeground", "Foreground");
+  st->ptr_gc = XCreateGC (st->dpy, st->b, GCForeground|GCLineWidth, &gcv);
+
+  gcv.foreground = get_pixel_resource (st->dpy, st->xgwa.colormap,
+                                       "background", "Background");
+  st->erase_gc = XCreateGC (st->dpy, st->b, GCForeground, &gcv);
+
+  if (st->ba) XFillRectangle (st->dpy, st->ba, st->erase_gc, 0, 0, st->size2, st->size2);
+  if (st->bb) XFillRectangle (st->dpy, st->bb, st->erase_gc, 0, 0, st->size2, st->size2);
+
+  return st;
+}
+
+static unsigned long
+compass_draw (Display *dpy, Window window, void *closure)
+{
+  struct state *st = (struct state *) closure;
+  XFillRectangle (st->dpy, st->b, st->erase_gc, 0, 0, st->xgwa.width, st->xgwa.height);
+
+  draw_compass (st);
+  draw_pointer (st);
+
+#ifdef HAVE_DOUBLE_BUFFER_EXTENSION
+  if (st->backb)
+    {
+      XdbeSwapInfo info[1];
+      info[0].swap_window = st->window;
+      info[0].swap_action = XdbeUndefined;
+      XdbeSwapBuffers (st->dpy, info, 1);
+    }
+  else
+#endif /* HAVE_DOUBLE_BUFFER_EXTENSION */
+    if (st->dbuf)
+      {
+        XCopyArea (st->dpy, st->b, st->window, st->erase_gc, 0, 0,
+                   st->size2, st->size2,
+                   st->xgwa.width/2 - st->x,
+                   st->xgwa.height/2 - st->y);
+        st->b = (st->b == st->ba ? st->bb : st->ba);
+      }
+
+  return st->delay;
+}
+
+static void
+compass_reshape (Display *dpy, Window window, void *closure, 
+                 unsigned int w, unsigned int h)
+{
+  struct state *st = (struct state *) closure;
+  XGetWindowAttributes (st->dpy, st->window, &st->xgwa);
+  st->size2 = MIN(st->xgwa.width, st->xgwa.height);
+  st->x = st->xgwa.width/2;
+  st->y = st->xgwa.height/2;
+}
+
+static Bool
+compass_event (Display *dpy, Window window, void *closure, XEvent *event)
+{
+  return False;
+}
+
+static void
+compass_free (Display *dpy, Window window, void *closure)
+{
+}
+
+
+
+static const char *compass_defaults [] = {
+  ".background:		#000000",
+  ".foreground:		#DDFFFF",
+  "*arrow1Foreground:	#FFF66A",
+  "*arrow2Foreground:	#F7D64A",
+  "*pointerForeground:	#FF0000",
+  "*delay:		20000",
+  "*doubleBuffer:	True",
+#ifdef HAVE_DOUBLE_BUFFER_EXTENSION
+  "*useDBE:		True",
+#endif /* HAVE_DOUBLE_BUFFER_EXTENSION */
+  0
+};
+
+static XrmOptionDescRec compass_options [] = {
+  { "-delay",		".delay",	XrmoptionSepArg, 0 },
+  { "-db",		".doubleBuffer", XrmoptionNoArg,  "True" },
+  { "-no-db",		".doubleBuffer", XrmoptionNoArg,  "False" },
+  { 0, 0, 0, 0 }
+};
+
+
+XSCREENSAVER_MODULE ("Compass", compass)