1attraction(6x)                XScreenSaver manual               attraction(6x)
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NAME

6       attraction - interactions of opposing forces
7

SYNOPSIS

9       attraction   [--display   host:display.screen]   [--foreground   color]
10       [--background color] [--window] [--root]  [--window-id  number][--mono]
11       [--install]  [--visual visual] [--points int] [--threshold int] [--mode
12       balls | lines | polygons | splines | filled-splines | tails  ]  [--size
13       int]  [--segments  int]  [--delay  usecs] [--color-shift int] [--radius
14       int] [--vx int] [--vy int] [--glow] [--noglow]  [--orbit]  [--viscosity
15       float]  [--walls]  [--nowalls]  [--maxspeed] [--nomaxspeed] [--correct-
16       bounce] [--fast-bounce] [--fps]
17

DESCRIPTION

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  be‐
22       gin  to  repel each other.  The attraction/repulsion is proportional to
23       the distance between any two particles.
24

OPTIONS

26       attraction accepts the following options:
27
28       --window
29               Draw on a newly-created window.  This is the default.
30
31       --root  Draw on the root window.
32
33       --window-id number
34               Draw on the specified window.
35
36       --mono  If on a color display, pretend we're on a monochrome display.
37
38       --install
39               Install a private colormap for the window.
40
41       --visual visual
42               Specify which visual to use.  Legal values are the  name  of  a
43               visual  class,  or the id number (decimal or hex) of a specific
44               visual.
45
46       --points integer
47               How many control points should be used, or 0 to select the num‐
48               ber randomly.  Default 0.  Between 3 and 15 works best.
49
50       --threshold integer
51               The  distance  (in  pixels) from each particle at which the at‐
52               tractive force becomes repulsive.  Default 100.
53
54       --mode balls | lines | polygons | tails | splines | filled-splines
55               In balls mode (the default) the control  points  are  drawn  as
56               filled  circles.   The  larger the circle, the more massive the
57               particle.
58
59               In lines mode, the control points  are  connected  by  straight
60               lines; the effect is something like qix.
61
62               In  polygons mode, the control points are connected by straight
63               lines, and filled in.  This is most interesting in color.
64
65               In splines mode, a closed spline is interpolated from the  con‐
66               trol points.
67
68               In  filled-splines  mode,  the splines are filled in instead of
69               being outlines.  This is most interesting in color.
70
71               In tails mode, the path which each particle  follows  is  indi‐
72               cated  by  a worm-like trail, whose length is controlled by the
73               segments parameter.
74
75       --size integer
76               The size of the balls in pixels, or 0, meaning  to  select  the
77               sizes  randomly  (the default.)  If this is specified, then all
78               balls will be the same size.  This option has an effect in  all
79               modes, since the ``size'' of the balls controls their mass.
80
81       --segments integer
82               If in lines or polygons mode, how many sets of line segments or
83               polygons should be drawn. Default 500.  This has no  effect  in
84               balls  mode.   If  segments is 0, then no segments will ever be
85               erased (this is only useful in color.)
86
87       --delay microseconds
88               How much of a delay should be introduced between steps  of  the
89               animation.  Default 10000, or about 0.01 seconds.
90
91       --color-shift int
92               If  on a color display, the color of the line segments or poly‐
93               gons will cycle through the color map.  This specifies how many
94               lines  will  be  drawn  before  a new color is chosen.  (When a
95               small number of colors are  available,  increasing  this  value
96               will  yield smoother transitions.)  Default 3.  This has no ef‐
97               fect in balls mode.
98
99       --radius
100               The size in pixels of the circle on which the points  are  ini‐
101               tially  positioned.   The  default is slightly smaller than the
102               size of the window.
103
104       --glow  This is consulted only in balls mode.  If  this  is  specified,
105               then  the  saturation of the colors of the points will vary ac‐
106               cording to their current acceleration.   This  has  the  effect
107               that  the  balls  flare brighter when they are reacting to each
108               other most strongly.
109
110               In glow mode, all of the balls will be drawn the same  (random)
111               color,  modulo  the  saturation  shifts.  In non-glow mode, the
112               balls will each be drawn in a random color that doesn't change.
113
114       --noglow
115               Don't do ``glowing.''  This is the default.
116
117       --vx pixels
118
119       --vy pixels
120               Initial velocity of the balls.  This has no effect  in  --orbit
121               mode.
122
123       --orbit Make the initial force on each ball be tangential to the circle
124               on which they are initially placed, with the right velocity  to
125               hold  them  in orbit about each other.  After a while, roundoff
126               errors will cause the orbit to decay.
127
128       --vmult float
129               In orbit mode, the initial velocity of the balls is  multiplied
130               by  this;  a number less than 1 will make the balls pull closer
131               together, and a larger number will make them move  apart.   The
132               default is 0.9, meaning a slight inward pull.
133
134       --viscosity float
135               This sets the viscosity of the hypothetical fluid through which
136               the control points move; the default is 1,  meaning  no  resis‐
137               tance.   Values  higher than 1 aren't interesting; lower values
138               cause less motion.
139
140               One interesting thing to try is
141
142                    attraction -viscosity 0.8 -points 300 \
143                    -size 10 -geometry =500x500
144
145               Give it a few seconds to settle down into a stable  clump,  and
146               then move the drag the mouse through it to make "waves".
147
148       --nowalls
149               This  will  cause the balls to continue on past the edge of the
150               screen or window.  They will still be kept  track  of  and  can
151               come back.
152
153       --walls This  will  cause the balls to bounce when they get to the edge
154               of the screen or window.  This is the default behavior.
155
156       --maxspeed
157               Imposes a maximum speed (default).  If a  ball  ends  up  going
158               faster  than  this,  it will be treated as though there were .9
159               viscosity until it is under the limit.  This  stops  the  balls
160               from  continually  accelerating  (which they have a tendency to
161               do), but also causes balls moving very fast to tend to clump in
162               the lower right corner.
163
164       --nomaxspeed
165               If this is specified, no maximum speed is set for the balls.
166
167       --fast-bounce
168               Uses the old, simple bouncing algorithm (default).  This simply
169               moves any ball that is out of bounds back to  a  wall  and  re‐
170               verses its velocity.  This works fine for most cases, but under
171               some circumstances, the simplification can lead to annoying ef‐
172               fects.
173
174       --correct-bounce
175               Uses  a more intelligent bouncing algorithm.  This method actu‐
176               ally reflects the balls off the walls  until  they  are  within
177               bounds.   This  can  be slow if balls are bouncing a whole lot,
178               perhaps because of -nomaxspeed.
179
180       --graphmode none | x | y | both | speed
181               For "x", "y", and "both", displays the given velocities of each
182               ball  as  a  bar  graph  in  the same window as the balls.  For
183               "speed", displays the total speed of  each  ball.   Default  is
184               "none".
185
186       --fps   Display the current frame rate and CPU load.
187

ENVIRONMENT

189       DISPLAY to get the default host and display number.
190
191       XENVIRONMENT
192               to  get  the  name of a resource file that overrides the global
193               resources stored in the RESOURCE_MANAGER property.
194
195       XSCREENSAVER_WINDOW
196               The window ID to use with --root.
197

SEE ALSO

199       X(1), xscreensaver(1)
200
202       Copyright © 1992, 1993, 1997 by Jamie  Zawinski.   Permission  to  use,
203       copy,  modify, distribute, and sell this software and its documentation
204       for any purpose is hereby granted without fee, provided that the  above
205       copyright  notice appear in all copies and that both that copyright no‐
206       tice and this permission notice appear in supporting documentation.  No
207       representations are made about the suitability of this software for any
208       purpose.  It is provided "as is" without express or implied warranty.
209

AUTHOR

211       Jamie Zawinski <jwz@jwz.org>, 13-aug-92.
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213       Viscosity support by Philip Edward Cutone, III.
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215       Walls, speed limit options, new bouncing, graphs, and tail mode fix  by
216       Matthew Strait. 31 March 2001
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220X Version 11               6.08-1.fc38 (17-Oct-2023)            attraction(6x)
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