1epicycle(6x) XScreenSaver manual epicycle(6x)
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6 epicycle - draws a point moving around a circle which moves around a
7 cicle which...
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10 epicycle [--display host:display.screen] [--root] [--window-id num‐
11 ber][--window] [--mono] [--install] [--noinstall] [--visual viz]
12 [--colors N] [--foreground name] [--color-shift N] [--delay microsec‐
13 onds] [--holdtime seconds] [--linewidth N] [--min_circles N]
14 [--max_circles N] [--min_speed number] [--max_speed number] [--harmon‐
15 ics N] [--timestep number] [--divisor_poisson probability] [--size_fac‐
16 tor_min number] [--size_factor_max number] [--fps]
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19 The epicycle program draws the path traced out by a point on the edge
20 of a circle. That circle rotates around a point on the rim of another
21 circle, and so on, several times. The random curves produced can be
22 simple or complex, convex or concave, but they are always closed curves
23 (they never go in indefinitely).
24 You can configure both the way the curves are drawn and the way in
26 which the random sequence of circles is generated, either with command-
27 line options or X resources.
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30 --display host:display.screen
31 Specifies which X display we should use (see the section DIS‐
32 PLAY NAMES in X(1) for more information about this option).
33 --root Draw on the root window.
35 --window-id number
37 Draw on the specified window.
38 --window
40 Draw on a newly-created window. This is the default.
41 --mono If on a color display, pretend we're on a monochrome display.
43 If we're on a mono display, we have no choice.
44 --install
46 Install a private colormap for the window.
47 --noinstall
49 Don't install a private colormap for the window.
50 --visual viz
52 Specify which visual to use. Legal values are the name of a
53 visual class, or the id number (decimal or hex) of a specific
54 visual. Possible choices include
55 default, best, mono, monochrome, gray, grey, color, staticgray,
57 staticcolor, truecolor, grayscale, greyscale, pseudocolor, di‐
58 rectcolor, number
59 If a decimal or hexadecimal number is used, XGetVisualInfo(3X)
61 is consulted to obtain the required visual.
62 --colors N
64 How many colors should be used (if possible). The colors are
65 chosen randomly.
66 --foreground name
68 With --mono, this option selects the foreground colour.
69 --delay microseconds
71 Specifies the delay between drawing successive line segments of
72 the path. If you do not specify -sync, some X servers may
73 batch up several drawing operations together, producing a less
74 smooth effect. This is more likely to happen in monochrome
75 mode (on monochrome servers or when --mono is specified).
76 --holdtime seconds
78 When the figure is complete, epicycle pauses this number of
79 seconds.
80 --linewidth N
82 Width in pixels of the body's track. Specifying values
83 greater than one may cause slower drawing. The fastest value
84 is usually zero, meaning one pixel.
85 --min_circles N
87 Smallest number of epicycles in the figure.
88 --max_circles N
90 Largest number of epicycles in the figure.
91 --min_speed number
93 Smallest possible value for the base speed of revolution of the
94 epicycles. The actual speeds of the epicycles vary from this
95 down to min_speed / harmonics.
96 --max_speed number
98 Smallest possible value for the base speed of revolution of the
99 epicycles.
100 --harmonics N
102 Number of possible harmonics; the larger this value is, the
103 greater the possible variety of possible speeds of epicycle.
104 --timestep number
106 Decreasing this value will reduce the distance the body moves
107 for each line segment, possibly producing a smoother figure.
108 Increasing it may produce faster results.
109 --divisor_poisson probability
111 Each epicycle rotates at a rate which is a factor of the base
112 speed. The speed of each epicycle is the base speed divided by
113 some integer between 1 and the value of the --harmonics option.
114 This integer is decided by starting at 1 and tossing a biased
115 coin. For each consecutive head, the value is incremented by
116 one. The integer will not be incremented above the value of
117 the --harmonics option. The argument of this option decides
118 the bias of the coin; it is the probability that that coin will
119 produce a head at any given toss.
120 --size_factor_min number
122 Epicycles are always at least this factor smaller than their
123 parents.
124 --size_factor_max number
126 Epicycles are never more than this factor smaller than their
127 parents.
128 --fps Display the current frame rate and CPU load. --timestep option
130 multiplied by the timestepCoarseFactor resource. The default
131 value of 1 will almost always work fast enough and so this re‐
132 source is not available as a command-line option.
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135 The program runs mostly without user interaction. When running on the
136 root window, no input is accepted. When running in its own window, the
137 program will exit if mouse button 3 is pressed. If any other mouse
138 button is pressed, the current figure will be abandoned and another
139 will be started.
140
142 The geometry of epicycles was perfected by Hipparchus of Rhodes at some
143 time around 125 B.C., 185 years after the birth of Aristarchus of
144 Samos, the inventor of the heliocentric universe model. Hipparchus ap‐
145 plied epicycles to the Sun and the Moon. Ptolemy of Alexandria went on
146 to apply them to what was then the known universe, at around 150 A.D.
147 Copernicus went on to apply them to the heliocentric model at the be‐
148 ginning of the sixteenth century. Johannes Kepler discovered that the
149 planets actually move in elliptical orbits in about 1602. The inverse-
150 square law of gravity was suggested by Boulliau in 1645. Isaac New‐
151 ton's Principia Mathematica was published in 1687, and proved that Ke‐
152 pler's laws derived from Newtonian gravitation.
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155 The colour selection is re-done for every figure. This may generate
156 too much network traffic for this program to work well over slow or
157 long links.
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160 DISPLAY to get the default host and display number.
161 XENVIRONMENT
163 to get the name of a resource file that overrides the global
164 resources stored in the RESOURCE_MANAGER property.
165 XSCREENSAVER_WINDOW
167 The window ID to use with --root.
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170 X(1), xscreensaver(1)
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173 Copyright © 1998, James Youngman. Permission to use, copy, modify,
174 distribute, and sell this software and its documentation for any pur‐
175 pose is hereby granted without fee, provided that the above copyright
176 notice appear in all copies and that both that copyright notice and
177 this permission notice appear in supporting documentation. No repre‐
178 sentations are made about the suitability of this software for any pur‐
179 pose. It is provided "as is" without express or implied warranty.
180
182 James Youngman <jay@gnu.org>, April 1998.
183X Version 11 6.06-1.fc37 (12-Dec-2022) epicycle(6x)