1attraction(6x) XScreenSaver manual attraction(6x)
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6 attraction - interactions of opposing forces
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9 attraction [-display host:display.screen] [-foreground color] [-back‐
10 ground color] [-window] [-root] [-mono] [-install] [-visual visual]
11 [-points int] [-threshold int] [-mode balls | lines | polygons |
12 splines | filled-splines | tails ] [-size int] [-segments int] [-delay
13 usecs] [-color-shift int] [-radius int] [-vx int] [-vy int] [-glow]
14 [-noglow] [-orbit] [-viscosity float] [-mouse] [-no-mouse] [-mouse-
15 size] [-walls] [-nowalls] [-maxspeed] [-nomaxspeed] [-correct-bounce]
16 [-fast-bounce]
17
19 The attraction program has several visually different modes of opera‐
20 tion, all of which are based on the interactions of a set of control
21 points which attract each other up to a certain distance, and then
22 begin to repel each other. The attraction/repulsion is proportional to
23 the distance between any two particles.
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26 attraction accepts the following options:
27 -window Draw on a newly-created window. This is the default.
29 -root Draw on the root window.
31 -mono If on a color display, pretend we're on a monochrome display.
33 -install
35 Install a private colormap for the window.
36 -visual visual
38 Specify which visual to use. Legal values are the name of a
39 visual class, or the id number (decimal or hex) of a specific
40 visual.
41 -points integer
43 How many control points should be used, or 0 to select the num‐
44 ber randomly. Default 0. Between 3 and 15 works best.
45 -threshold integer
47 The distance (in pixels) from each particle at which the
48 attractive force becomes repulsive. Default 100.
49 -mode balls | lines | polygons | tails | splines | filled-splines
51 In balls mode (the default) the control points are drawn as
52 filled circles. The larger the circle, the more massive the
53 particle.
54 In lines mode, the control points are connected by straight
56 lines; the effect is something like qix.
57 In polygons mode, the control points are connected by straight
59 lines, and filled in. This is most interesting in color.
60 In splines mode, a closed spline is interpolated from the con‐
62 trol points.
63 In filled-splines mode, the splines are filled in instead of
65 being outlines. This is most interesting in color.
66 In tails mode, the path which each particle follows is indi‐
68 cated by a worm-like trail, whose length is controlled by the
69 segments parameter.
70 -size integer
72 The size of the balls in pixels, or 0, meaning to select the
73 sizes randomly (the default.) If this is specified, then all
74 balls will be the same size. This option has an effect in all
75 modes, since the ``size'' of the balls controls their mass.
76 -segments integer
78 If in lines or polygons mode, how many sets of line segments or
79 polygons should be drawn. Default 500. This has no effect in
80 balls mode. If segments is 0, then no segments will ever be
81 erased (this is only useful in color.)
82 -delay microseconds
84 How much of a delay should be introduced between steps of the
85 animation. Default 10000, or about 0.01 seconds.
86 -color-shift int
88 If on a color display, the color of the line segments or poly‐
89 gons will cycle through the color map. This specifies how many
90 lines will be drawn before a new color is chosen. (When a
91 small number of colors are available, increasing this value
92 will yield smoother transitions.) Default 3. This has no
93 effect in balls mode.
94 -radius The size in pixels of the circle on which the points are ini‐
96 tially positioned. The default is slightly smaller than the
97 size of the window.
98 -glow This is consulted only in balls mode. If this is specified,
100 then the saturation of the colors of the points will vary
101 according to their current acceleration. This has the effect
102 that the balls flare brighter when they are reacting to each
103 other most strongly.
104 In glow mode, all of the balls will be drawn the same (random)
106 color, modulo the saturation shifts. In non-glow mode, the
107 balls will each be drawn in a random color that doesn't change.
108 -noglow Don't do ``glowing.'' This is the default.
110 -vx pixels
112 -vy pixels
114 Initial velocity of the balls. This has no effect in -orbit
115 mode.
116 -orbit Make the initial force on each ball be tangential to the circle
118 on which they are initially placed, with the right velocity to
119 hold them in orbit about each other. After a while, roundoff
120 errors will cause the orbit to decay.
121 -vmult float
123 In orbit mode, the initial velocity of the balls is multiplied
124 by this; a number less than 1 will make the balls pull closer
125 together, and a larger number will make them move apart. The
126 default is 0.9, meaning a slight inward pull.
127 -viscosity float
129 This sets the viscosity of the hypothetical fluid through which
130 the control points move; the default is 1, meaning no resis‐
131 tance. Values higher than 1 aren't interesting; lower values
132 cause less motion.
133 One interesting thing to try is
135 attraction -viscosity 0.8 -points 75 \
136 -mouse -geometry =500x500
137 Give it a few seconds to settle down into a stable clump, and
138 then move the mouse through it to make "waves".
139 -mouse This will cause the mouse to be considered a control point; it
141 will not be drawn, but it will influence the other points, so
142 you can wave the mouse and influence the images being created.
143 -no-mouse
145 Turns off -mouse.
146 -mouse-size integer
148 In -mouse mode, this sets the mass of the mouse (analogously to
149 the -size parameter.)
150 -nowalls
152 This will cause the balls to continue on past the edge of the
153 screen or window. They will still be kept track of and can
154 come back.
155 -walls This will cause the balls to bounce when they get to the edge
157 of the screen or window. This is the default behavior.
158 -maxspeed
160 Imposes a maximum speed (default). If a ball ends up going
161 faster than this, it will be treated as though there were .9
162 viscosity until it is under the limit. This stops the balls
163 from continually accelerating (which they have a tendency to
164 do), but also causes balls moving very fast to tend to clump in
165 the lower right corner.
166 -nomaxspeed
168 If this is specified, no maximum speed is set for the balls.
169 -fast-bounce
171 Uses the old, simple bouncing algorithm (default). This simply
172 moves any ball that is out of bounds back to a wall and
173 reverses its velocity. This works fine for most cases, but
174 under some circumstances, the simplification can lead to annoy‐
175 ing effects.
176 -correct-bounce
178 Uses a more intelligent bouncing algorithm. This method actu‐
179 ally reflects the balls off the walls until they are within
180 bounds. This can be slow if balls are bouncing a whole lot,
181 perhaps because of -nomaxspeed.
182 -graphmode none | x | y | both | speed
184 For "x", "y", and "both", displays the given velocities of each
185 ball as a bar graph in the same window as the balls. For
186 "speed", displays the total speed of each ball. Default is
187 "none".
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190 DISPLAY to get the default host and display number.
191 XENVIRONMENT
193 to get the name of a resource file that overrides the global
194 resources stored in the RESOURCE_MANAGER property.
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197 X(1), xscreensaver(1)
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200 Copyright © 1992, 1993, 1997 by Jamie Zawinski. Permission to use,
201 copy, modify, distribute, and sell this software and its documentation
202 for any purpose is hereby granted without fee, provided that the above
203 copyright notice appear in all copies and that both that copyright
204 notice and this permission notice appear in supporting documentation.
205 No representations are made about the suitability of this software for
206 any purpose. It is provided "as is" without express or implied war‐
207 ranty.
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210 Jamie Zawinski <jwz@jwz.org>, 13-aug-92.
211 Viscosity and mouse support by Philip Edward Cutone, III.
213 Walls, speed limit options, new bouncing, graphs, and tail mode fix by
215 Matthew Strait. 31 March 2001
216X Version 11 5.05-3 (06-Apr-2008) attraction(6x)