/usr/share/graphviz/lefty/fractal.lefty is in graphviz 2.36.0-0ubuntu3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 | load ('def.lefty');
definit ();
#
# initialize window data
#
canvas = defcanvas;
wrect = [0 = ['x' = 0; 'y' = 0;]; 1 = ['x' = 400; 'y' = 500;];];
setwidgetattr (canvas, ['window' = wrect;]);
sq = function (x) {
return x * x;
};
# data structures
#
length = 300;
center = ['x' = 200; 'y' = 250;];
radius = 2 * length / sqrt (12);
fractalangle = 0;
maxlevel = 2;
# drawing functions
#
# draw a Koch curve (a ``snowflake'' fractal)
#
# start with a triangle and keep replacing edges
# with the construct: _/\_
# until the recursion level reaches 'maxlevel'
#
fractal = function (level, length, angle) {
local nlength, newpenpos;
if (level >= maxlevel) {
newpenpos.x = penpos.x + length * cos (angle);
newpenpos.y = penpos.y + length * sin (angle);
line (canvas, null, penpos, newpenpos, ['color' = 1;]);
penpos = newpenpos;
return;
}
nlength = length / 3;
fractal (level + 1, nlength, angle);
fractal (level + 1, nlength, angle + 60);
fractal (level + 1, nlength, angle - 60);
fractal (level + 1, nlength, angle);
};
drawfractal = function () {
clear (canvas);
setpick (canvas, center, wrect);
penpos = [
'x' = center.x + cos (fractalangle + 210) * radius;
'y' = center.y + sin (fractalangle + 210) * radius;
];
fractal (0, length, fractalangle + 60);
fractal (0, length, fractalangle - 60);
fractal (0, length, fractalangle - 180);
remove ('penpos');
};
# editing functions
#
# transform the fractal.
#
# map point 'prevpoint' to point 'currpoint'
# with respect to the center of the fractal.
#
transformfractal = function (prevpoint, currpoint) {
local prevtan, currtan, prevradius, currradius;
prevtan = atan (prevpoint.y - center.y, prevpoint.x - center.x);
currtan = atan (currpoint.y - center.y, currpoint.x - center.x);
fractalangle = fractalangle + (currtan - prevtan);
prevradius = sqrt (
sq (prevpoint.y - center.y) + sq (prevpoint.x - center.x)
);
currradius = sqrt (
sq (currpoint.y - center.y) + sq (currpoint.x - center.x)
);
radius = radius / prevradius * currradius;
length = radius / 2 * sqrt (12);
};
# user interface functions
#
# bind changes to the fractal to user actions
#
leftup = function (data) {
transformfractal (data.ppos, data.pos);
drawfractal ();
};
dops = function () {
local s;
s = ['x' = 8 * 300; 'y' = 10.5 * 300;];
canvas = createwidget (-1, ['type' = 'ps'; 'size' = s;]);
setwidgetattr (canvas, ['window' = wrect;]);
drawfractal ();
destroywidget (canvas);
canvas=defcanvas;
};
transformfractal (['x' = 0; 'y' = 0;], ['x' = 0; 'y' = 0;]);
drawfractal ();
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