--- /dev/null
+/* xscreensaver, Copyright (c) 1992, 1995, 1996, 1997
+ * 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.
+ */
+
+/* Algorithm from a Mac program by Chris Tate, written in 1988 or so. */
+
+/* 18-Sep-97: Johannes Keukelaar (johannes@nada.kth.se): Improved screen
+ * eraser.
+ * 10-May-97: merged ellipse code by Dan Stromberg <strombrg@nis.acs.uci.edu>
+ * as found in xlockmore 4.03a10.
+ * 1992: jwz created.
+ */
+
+#include <math.h>
+#include "screenhack.h"
+#include "erase.h"
+
+static double sins [360];
+static double coss [360];
+
+static GC draw_gc;
+static unsigned int default_fg_pixel;
+static int sleep_time;
+
+static void
+init_helix (Display *dpy, Window window)
+{
+ int i;
+ XGCValues gcv;
+ XWindowAttributes xgwa;
+ Colormap cmap;
+ XGetWindowAttributes (dpy, window, &xgwa);
+ cmap = xgwa.colormap;
+ gcv.foreground = default_fg_pixel =
+ get_pixel_resource ("foreground", "Foreground", dpy, cmap);
+ draw_gc = XCreateGC (dpy, window, GCForeground, &gcv);
+ gcv.foreground = get_pixel_resource ("background", "Background", dpy, cmap);
+
+ for (i = 0; i < 360; i++)
+ {
+ sins [i] = sin ((((double) i) / 180.0) * M_PI);
+ coss [i] = cos ((((double) i) / 180.0) * M_PI);
+ }
+}
+
+static int
+gcd (int a, int b)
+{
+ while (b > 0)
+ {
+ int tmp;
+ tmp = a % b;
+ a = b;
+ b = tmp;
+ }
+ return (a < 0 ? -a : a);
+}
+
+static void
+helix (Display *dpy, Window window,
+ int radius1, int radius2, int d_angle,
+ int factor1, int factor2, int factor3, int factor4)
+{
+ XWindowAttributes xgwa;
+ int width, height;
+ int xmid, ymid;
+ int x1, y1, x2, y2, angle, limit;
+ int i;
+
+ XClearWindow (dpy, window);
+ XGetWindowAttributes (dpy, window, &xgwa);
+ width = xgwa.width;
+ height = xgwa.height;
+
+ xmid = width / 2;
+ ymid = height / 2;
+ x1 = xmid;
+ y1 = ymid + radius2;
+ x2 = xmid;
+ y2 = ymid + radius1;
+ angle = 0;
+ limit = 1 + (360 / gcd (360, d_angle));
+
+ for (i = 0; i < limit; i++)
+ {
+ int tmp;
+#define pmod(x,y) (tmp=((x) % (y)), (tmp >= 0 ? tmp : (tmp + (y))))
+
+ x1 = xmid + (((double) radius1) * sins [pmod ((angle * factor1), 360)]);
+ y1 = ymid + (((double) radius2) * coss [pmod ((angle * factor2), 360)]);
+ XDrawLine (dpy, window, draw_gc, x1, y1, x2, y2);
+ x2 = xmid + (((double) radius2) * sins [pmod ((angle * factor3), 360)]);
+ y2 = ymid + (((double) radius1) * coss [pmod ((angle * factor4), 360)]);
+
+ XDrawLine (dpy, window, draw_gc, x1, y1, x2, y2);
+ angle += d_angle;
+ XFlush (dpy);
+ }
+}
+
+static void
+trig (Display *dpy, Window window,
+ int d_angle, int factor1, int factor2,
+ int offset, int d_angle_offset, int dir, int density)
+{
+ XWindowAttributes xgwa;
+ int width, height;
+ int xmid, ymid;
+ int x1, y1, x2, y2;
+ int tmp, angle;
+ Colormap cmap;
+
+ XClearWindow (dpy, window);
+ XGetWindowAttributes (dpy, window, &xgwa);
+ cmap = xgwa.colormap;
+ width = xgwa.width;
+ height = xgwa.height;
+
+ xmid = width / 2;
+ ymid = height / 2;
+
+ while (d_angle >= -360 && d_angle <= 360)
+ {
+ angle = d_angle + d_angle_offset;
+ x1 = (sins [pmod(angle * factor1, 360)] * xmid) + xmid;
+ y1 = (coss [pmod(angle * factor1, 360)] * ymid) + ymid;
+ x2 = (sins [pmod(angle * factor2 + offset, 360)] * xmid) + xmid;
+ y2 = (coss [pmod(angle * factor2 + offset, 360)] * ymid) + ymid;
+ XDrawLine(dpy, window, draw_gc, x1, y1, x2, y2);
+ tmp = (int) 360 / (2 * density * factor1 * factor2);
+ if (tmp == 0) /* Do not want it getting stuck... */
+ tmp = 1; /* Would not need if floating point */
+ d_angle += dir * tmp;
+ }
+}
+
+#define min(a,b) ((a)<(b)?(a):(b))
+
+static void
+random_helix (Display *dpy, Window window, XColor *color, Bool *got_color)
+{
+ Colormap cmap;
+ int width, height;
+ int radius, radius1, radius2, d_angle, factor1, factor2, factor3, factor4;
+ double divisor;
+ XWindowAttributes xgwa;
+ XGetWindowAttributes (dpy, window, &xgwa);
+ width = xgwa.width;
+ height = xgwa.height;
+ cmap = xgwa.colormap;
+
+ radius = min (width, height) / 2;
+
+ d_angle = 0;
+ factor1 = 2;
+ factor2 = 2;
+ factor3 = 2;
+ factor4 = 2;
+
+ divisor = ((frand (3.0) + 1) * (((random() & 1) * 2) - 1));
+
+ if ((random () & 1) == 0)
+ {
+ radius1 = radius;
+ radius2 = radius / divisor;
+ }
+ else
+ {
+ radius2 = radius;
+ radius1 = radius / divisor;
+ }
+
+ while (gcd (360, d_angle) >= 2)
+ d_angle = random () % 360;
+
+#define random_factor() \
+ (((random() % 7) ? ((random() & 1) + 1) : 3) \
+ * (((random() & 1) * 2) - 1))
+
+ while (gcd (gcd (gcd (factor1, factor2), factor3), factor4) != 1)
+ {
+ factor1 = random_factor ();
+ factor2 = random_factor ();
+ factor3 = random_factor ();
+ factor4 = random_factor ();
+ }
+
+ if (mono_p)
+ XSetForeground (dpy, draw_gc, default_fg_pixel);
+ else
+ {
+ hsv_to_rgb (random () % 360, frand (1.0), frand (0.5) + 0.5,
+ &color->red, &color->green, &color->blue);
+ if ((*got_color = XAllocColor (dpy, cmap, color)))
+ XSetForeground (dpy, draw_gc, color->pixel);
+ else
+ XSetForeground (dpy, draw_gc, default_fg_pixel);
+ }
+ helix (dpy, window, radius1, radius2, d_angle,
+ factor1, factor2, factor3, factor4);
+}
+
+static void
+random_trig (Display *dpy, Window window, XColor *color, Bool *got_color)
+{
+ Colormap cmap;
+ int width, height;
+ int radius, d_angle, factor1, factor2;
+ int offset, d_angle_offset, dir, density;
+
+ XWindowAttributes xgwa;
+ XGetWindowAttributes (dpy, window, &xgwa);
+ width = xgwa.width;
+ height = xgwa.height;
+ cmap = xgwa.colormap;
+
+ radius = min (width, height) / 2;
+
+ d_angle = 0;
+ factor1 = (random() % 8) + 1;
+ do {
+ factor2 = (random() % 8) + 1;
+ } while (factor1 == factor2);
+
+ dir = (random() & 1) ? 1 : -1;
+ d_angle_offset = random() % 360;
+ offset = ((random() % ((360 / 4) - 1)) + 1) / 4;
+ density = 1 << ((random() % 4) + 4); /* Higher density, higher angles */
+
+ if (mono_p)
+ XSetForeground (dpy, draw_gc, default_fg_pixel);
+ else
+ {
+ hsv_to_rgb (random () % 360, frand (1.0), frand (0.5) + 0.5,
+ &color->red, &color->green, &color->blue);
+ if ((*got_color = XAllocColor (dpy, cmap, color)))
+ XSetForeground (dpy, draw_gc, color->pixel);
+ else
+ XSetForeground (dpy, draw_gc, default_fg_pixel);
+ }
+ trig (dpy, window, d_angle, factor1, factor2,
+ offset, d_angle_offset, dir, density);
+}
+
+static void
+random_helix_or_trig (Display *dpy, Window window)
+{
+ Bool free_color = False;
+ XColor color;
+ int width, height;
+ XWindowAttributes xgwa;
+ Colormap cmap;
+ XGetWindowAttributes (dpy, window, &xgwa);
+ width = xgwa.width;
+ height = xgwa.height;
+ cmap = xgwa.colormap;
+
+ if (random() & 1)
+ random_helix(dpy, window, &color, &free_color);
+ else
+ random_trig(dpy, window, &color, &free_color);
+
+ XSync (dpy, False);
+ screenhack_handle_events (dpy);
+ sleep ( sleep_time );
+
+ screenhack_handle_events (dpy);
+ erase_full_window(dpy, window);
+
+ if (free_color) XFreeColors (dpy, cmap, &color.pixel, 1, 0);
+ XSync (dpy, False);
+ screenhack_handle_events (dpy);
+ sleep (1);
+}
+
+\f
+char *progclass = "Helix";
+
+char *defaults [] = {
+ ".background: black",
+ "*delay: 5",
+ 0
+};
+
+XrmOptionDescRec options [] = {
+ { "-delay", ".delay", XrmoptionSepArg, 0 },
+ { 0 },
+};
+int options_size = (sizeof (options) / sizeof (options[0]));
+
+void
+screenhack (Display *dpy, Window window)
+{
+ sleep_time = get_integer_resource("delay", "Integer");
+ init_helix (dpy, window);
+ while (1)
+ random_helix_or_trig (dpy, window);
+}
projects / xscreensaver / blobdiff