1 /* xscreensaver, Copyright (c) 1992, 1995, 1996, 1997
2 * Jamie Zawinski <jwz@netscape.com>
4 * Permission to use, copy, modify, distribute, and sell this software and its
5 * documentation for any purpose is hereby granted without fee, provided that
6 * the above copyright notice appear in all copies and that both that
7 * copyright notice and this permission notice appear in supporting
8 * documentation. No representations are made about the suitability of this
9 * software for any purpose. It is provided "as is" without express or
13 /* Algorithm from a Mac program by Chris Tate, written in 1988 or so. */
15 /* 10-May-97: merged ellipse code by Dan Stromberg <strombrg@nis.acs.uci.edu>
16 * as found in xlockmore 4.03a10.
21 #include "screenhack.h"
23 static double sins [360];
24 static double coss [360];
26 static GC draw_gc, erase_gc;
27 static unsigned int default_fg_pixel;
30 init_helix (Display *dpy, Window window)
34 XWindowAttributes xgwa;
36 XGetWindowAttributes (dpy, window, &xgwa);
38 gcv.foreground = default_fg_pixel =
39 get_pixel_resource ("foreground", "Foreground", dpy, cmap);
40 draw_gc = XCreateGC (dpy, window, GCForeground, &gcv);
41 gcv.foreground = get_pixel_resource ("background", "Background", dpy, cmap);
42 erase_gc = XCreateGC (dpy, window, GCForeground, &gcv);
44 for (i = 0; i < 360; i++)
46 sins [i] = sin ((((double) i) / 180.0) * M_PI);
47 coss [i] = cos ((((double) i) / 180.0) * M_PI);
61 return (a < 0 ? -a : a);
65 helix (Display *dpy, Window window,
66 int radius1, int radius2, int d_angle,
67 int factor1, int factor2, int factor3, int factor4)
69 XWindowAttributes xgwa;
72 int x1, y1, x2, y2, angle, limit;
75 XClearWindow (dpy, window);
76 XGetWindowAttributes (dpy, window, &xgwa);
87 limit = 1 + (360 / gcd (360, d_angle));
89 for (i = 0; i < limit; i++)
92 #define pmod(x,y) (tmp=((x) % (y)), (tmp >= 0 ? tmp : (tmp + (y))))
94 x1 = xmid + (((double) radius1) * sins [pmod ((angle * factor1), 360)]);
95 y1 = ymid + (((double) radius2) * coss [pmod ((angle * factor2), 360)]);
96 XDrawLine (dpy, window, draw_gc, x1, y1, x2, y2);
97 x2 = xmid + (((double) radius2) * sins [pmod ((angle * factor3), 360)]);
98 y2 = ymid + (((double) radius1) * coss [pmod ((angle * factor4), 360)]);
100 XDrawLine (dpy, window, draw_gc, x1, y1, x2, y2);
107 trig (Display *dpy, Window window,
108 int d_angle, int factor1, int factor2,
109 int offset, int d_angle_offset, int dir, int density)
111 XWindowAttributes xgwa;
118 XClearWindow (dpy, window);
119 XGetWindowAttributes (dpy, window, &xgwa);
120 cmap = xgwa.colormap;
122 height = xgwa.height;
127 while (d_angle >= -360 && d_angle <= 360)
129 angle = d_angle + d_angle_offset;
130 x1 = (sins [pmod(angle * factor1, 360)] * xmid) + xmid;
131 y1 = (coss [pmod(angle * factor1, 360)] * ymid) + ymid;
132 x2 = (sins [pmod(angle * factor2 + offset, 360)] * xmid) + xmid;
133 y2 = (coss [pmod(angle * factor2 + offset, 360)] * ymid) + ymid;
134 XDrawLine(dpy, window, draw_gc, x1, y1, x2, y2);
135 tmp = (int) 360 / (2 * density * factor1 * factor2);
136 if (tmp == 0) /* Do not want it getting stuck... */
137 tmp = 1; /* Would not need if floating point */
138 d_angle += dir * tmp;
142 #define min(a,b) ((a)<(b)?(a):(b))
145 random_helix (Display *dpy, Window window, XColor *color, Bool *got_color)
149 int radius, radius1, radius2, d_angle, factor1, factor2, factor3, factor4;
151 XWindowAttributes xgwa;
152 XGetWindowAttributes (dpy, window, &xgwa);
154 height = xgwa.height;
155 cmap = xgwa.colormap;
157 radius = min (width, height) / 2;
165 divisor = ((frand (3.0) + 1) * (((random() & 1) * 2) - 1));
167 if ((random () & 1) == 0)
170 radius2 = radius / divisor;
175 radius1 = radius / divisor;
178 while (gcd (360, d_angle) >= 2)
179 d_angle = random () % 360;
181 #define random_factor() \
182 (((random() % 7) ? ((random() & 1) + 1) : 3) \
183 * (((random() & 1) * 2) - 1))
185 while (gcd (gcd (gcd (factor1, factor2), factor3), factor4) != 1)
187 factor1 = random_factor ();
188 factor2 = random_factor ();
189 factor3 = random_factor ();
190 factor4 = random_factor ();
194 XSetForeground (dpy, draw_gc, default_fg_pixel);
197 hsv_to_rgb (random () % 360, frand (1.0), frand (0.5) + 0.5,
198 &color->red, &color->green, &color->blue);
199 if ((*got_color = XAllocColor (dpy, cmap, color)))
200 XSetForeground (dpy, draw_gc, color->pixel);
202 XSetForeground (dpy, draw_gc, default_fg_pixel);
204 helix (dpy, window, radius1, radius2, d_angle,
205 factor1, factor2, factor3, factor4);
209 random_trig (Display *dpy, Window window, XColor *color, Bool *got_color)
213 int radius, d_angle, factor1, factor2;
214 int offset, d_angle_offset, dir, density;
216 XWindowAttributes xgwa;
217 XGetWindowAttributes (dpy, window, &xgwa);
219 height = xgwa.height;
220 cmap = xgwa.colormap;
222 radius = min (width, height) / 2;
225 factor1 = (random() % 8) + 1;
227 factor2 = (random() % 8) + 1;
228 } while (factor1 == factor2);
230 dir = (random() & 1) ? 1 : -1;
231 d_angle_offset = random() % 360;
232 offset = ((random() % ((360 / 4) - 1)) + 1) / 4;
233 density = 1 << ((random() % 4) + 4); /* Higher density, higher angles */
236 XSetForeground (dpy, draw_gc, default_fg_pixel);
239 hsv_to_rgb (random () % 360, frand (1.0), frand (0.5) + 0.5,
240 &color->red, &color->green, &color->blue);
241 if ((*got_color = XAllocColor (dpy, cmap, color)))
242 XSetForeground (dpy, draw_gc, color->pixel);
244 XSetForeground (dpy, draw_gc, default_fg_pixel);
246 trig (dpy, window, d_angle, factor1, factor2,
247 offset, d_angle_offset, dir, density);
251 random_helix_or_trig (Display *dpy, Window window)
254 Bool free_color = False;
257 XWindowAttributes xgwa;
259 XGetWindowAttributes (dpy, window, &xgwa);
261 height = xgwa.height;
262 cmap = xgwa.colormap;
265 random_helix(dpy, window, &color, &free_color);
267 random_trig(dpy, window, &color, &free_color);
272 for (i = 0; i < height; i++)
274 int y = (random () % height);
275 XDrawLine (dpy, window, erase_gc, 0, y, width, y);
280 XClearWindow (dpy, window);
281 if (free_color) XFreeColors (dpy, cmap, &color.pixel, 1, 0);
287 char *progclass = "Helix";
289 char *defaults [] = {
290 "Helix.background: black", /* to placate SGI */
294 XrmOptionDescRec options [] = { { 0, } };
297 screenhack (Display *dpy, Window window)
299 init_helix (dpy, window);
301 random_helix_or_trig (dpy, window);