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] [-walls] [-nowalls] [-maxspeed]
15 [-nomaxspeed] [-correct-bounce] [-fast-bounce] [-fps]
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18 The attraction program has several visually different modes of opera‐
19 tion, all of which are based on the interactions of a set of control
20 points which attract each other up to a certain distance, and then be‐
21 gin to repel each other. The attraction/repulsion is proportional to
22 the distance between any two particles.
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25 attraction accepts the following options:
26 -window Draw on a newly-created window. This is the default.
28 -root Draw on the root window.
30 -mono If on a color display, pretend we're on a monochrome display.
32 -install
34 Install a private colormap for the window.
35 -visual visual
37 Specify which visual to use. Legal values are the name of a
38 visual class, or the id number (decimal or hex) of a specific
39 visual.
40 -points integer
42 How many control points should be used, or 0 to select the num‐
43 ber randomly. Default 0. Between 3 and 15 works best.
44 -threshold integer
46 The distance (in pixels) from each particle at which the at‐
47 tractive force becomes repulsive. Default 100.
48 -mode balls | lines | polygons | tails | splines | filled-splines
50 In balls mode (the default) the control points are drawn as
51 filled circles. The larger the circle, the more massive the
52 particle.
53 In lines mode, the control points are connected by straight
55 lines; the effect is something like qix.
56 In polygons mode, the control points are connected by straight
58 lines, and filled in. This is most interesting in color.
59 In splines mode, a closed spline is interpolated from the con‐
61 trol points.
62 In filled-splines mode, the splines are filled in instead of
64 being outlines. This is most interesting in color.
65 In tails mode, the path which each particle follows is indi‐
67 cated by a worm-like trail, whose length is controlled by the
68 segments parameter.
69 -size integer
71 The size of the balls in pixels, or 0, meaning to select the
72 sizes randomly (the default.) If this is specified, then all
73 balls will be the same size. This option has an effect in all
74 modes, since the ``size'' of the balls controls their mass.
75 -segments integer
77 If in lines or polygons mode, how many sets of line segments or
78 polygons should be drawn. Default 500. This has no effect in
79 balls mode. If segments is 0, then no segments will ever be
80 erased (this is only useful in color.)
81 -delay microseconds
83 How much of a delay should be introduced between steps of the
84 animation. Default 10000, or about 0.01 seconds.
85 -color-shift int
87 If on a color display, the color of the line segments or poly‐
88 gons will cycle through the color map. This specifies how many
89 lines will be drawn before a new color is chosen. (When a
90 small number of colors are available, increasing this value
91 will yield smoother transitions.) Default 3. This has no ef‐
92 fect in balls mode.
93 -radius The size in pixels of the circle on which the points are ini‐
95 tially positioned. The default is slightly smaller than the
96 size of the window.
97 -glow This is consulted only in balls mode. If this is specified,
99 then the saturation of the colors of the points will vary ac‐
100 cording to their current acceleration. This has the effect
101 that the balls flare brighter when they are reacting to each
102 other most strongly.
103 In glow mode, all of the balls will be drawn the same (random)
105 color, modulo the saturation shifts. In non-glow mode, the
106 balls will each be drawn in a random color that doesn't change.
107 -noglow Don't do ``glowing.'' This is the default.
109 -vx pixels
111 -vy pixels
113 Initial velocity of the balls. This has no effect in -orbit
114 mode.
115 -orbit Make the initial force on each ball be tangential to the circle
117 on which they are initially placed, with the right velocity to
118 hold them in orbit about each other. After a while, roundoff
119 errors will cause the orbit to decay.
120 -vmult float
122 In orbit mode, the initial velocity of the balls is multiplied
123 by this; a number less than 1 will make the balls pull closer
124 together, and a larger number will make them move apart. The
125 default is 0.9, meaning a slight inward pull.
126 -viscosity float
128 This sets the viscosity of the hypothetical fluid through which
129 the control points move; the default is 1, meaning no resis‐
130 tance. Values higher than 1 aren't interesting; lower values
131 cause less motion.
132 One interesting thing to try is
134 attraction -viscosity 0.8 -points 300 \
136 -size 10 -geometry =500x500
137 Give it a few seconds to settle down into a stable clump, and
139 then move the drag the mouse through it to make "waves".
140 -nowalls
142 This will cause the balls to continue on past the edge of the
143 screen or window. They will still be kept track of and can
144 come back.
145 -walls This will cause the balls to bounce when they get to the edge
147 of the screen or window. This is the default behavior.
148 -maxspeed
150 Imposes a maximum speed (default). If a ball ends up going
151 faster than this, it will be treated as though there were .9
152 viscosity until it is under the limit. This stops the balls
153 from continually accelerating (which they have a tendency to
154 do), but also causes balls moving very fast to tend to clump in
155 the lower right corner.
156 -nomaxspeed
158 If this is specified, no maximum speed is set for the balls.
159 -fast-bounce
161 Uses the old, simple bouncing algorithm (default). This simply
162 moves any ball that is out of bounds back to a wall and re‐
163 verses its velocity. This works fine for most cases, but under
164 some circumstances, the simplification can lead to annoying ef‐
165 fects.
166 -correct-bounce
168 Uses a more intelligent bouncing algorithm. This method actu‐
169 ally reflects the balls off the walls until they are within
170 bounds. This can be slow if balls are bouncing a whole lot,
171 perhaps because of -nomaxspeed.
172 -graphmode none | x | y | both | speed
174 For "x", "y", and "both", displays the given velocities of each
175 ball as a bar graph in the same window as the balls. For
176 "speed", displays the total speed of each ball. Default is
177 "none".
178 -fps Display the current frame rate and CPU load.
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182 DISPLAY to get the default host and display number.
183 XENVIRONMENT
185 to get the name of a resource file that overrides the global
186 resources stored in the RESOURCE_MANAGER property.
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189 X(1), xscreensaver(1)
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192 Copyright © 1992, 1993, 1997 by Jamie Zawinski. Permission to use,
193 copy, modify, distribute, and sell this software and its documentation
194 for any purpose is hereby granted without fee, provided that the above
195 copyright notice appear in all copies and that both that copyright no‐
196 tice and this permission notice appear in supporting documentation. No
197 representations are made about the suitability of this software for any
198 purpose. It is provided "as is" without express or implied warranty.
199
201 Jamie Zawinski <jwz@jwz.org>, 13-aug-92.
202 Viscosity support by Philip Edward Cutone, III.
204 Walls, speed limit options, new bouncing, graphs, and tail mode fix by
206 Matthew Strait. 31 March 2001
207X Version 11 6.00-4.fc34 (05-May-2021) attraction(6x)