/usr/share/doc/libplplot12/examples/ada/x27a.adb is in libplplot-ada1-dev 5.10.0+dfsg-1.
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 | -- $Id: x27a.adb 11860 2011-08-05 10:23:37Z andrewross $
-- Drawing "spirograph" curves - epitrochoids, cycolids, roulettes
-- Copyright (C) 2008 Jerry Bauck
-- This file is part of PLplot.
-- PLplot is free software; you can redistribute it and/or modify
-- it under the terms of the GNU Library General Public License as published
-- by the Free Software Foundation; either version 2 of the License, or
-- (at your option) any later version.
-- PLplot is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-- GNU Library General Public License for more details.
-- You should have received a copy of the GNU Library General Public License
-- along with PLplot; if not, write to the Free Software
-- Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
with
Ada.Numerics,
Ada.Numerics.Long_Elementary_Functions,
PLplot_Auxiliary,
PLplot_Traditional;
use
Ada.Numerics,
Ada.Numerics.Long_Elementary_Functions,
PLplot_Auxiliary,
PLplot_Traditional;
------------------------------------------------------------------------------
-- Generates two kinds of plots:
-- - construction of a cycloid (animated)
-- - series of epitrochoids and hypotrochoids
------------------------------------------------------------------------------
procedure x27a is
-- R, r, p, N
-- R and r should be integers to give correct termination of the
-- angle loop using gcd.
-- N.B. N is just a place holder since it is no longer used
-- (because we now have proper termination of the angle loop).
params : Real_Matrix(0 .. 8, 0 .. 3) :=
((21.0, 7.0, 7.0, 3.0),
(21.0, 7.0, 10.0, 3.0),
(21.0, -7.0, 10.0, 3.0),
(20.0, 3.0, 7.0, 20.0),
(20.0, 3.0, 10.0, 20.0),
(20.0, -3.0, 10.0, 20.0),
(20.0, 13.0, 7.0, 20.0),
(20.0, 13.0, 20.0, 20.0),
(20.0,-13.0, 20.0, 20.0));
fill : Boolean;
-- To understand why spiro is written this way you need to understand the
-- C code from which this was derived. In the main C program, params
-- is a two-dimensional array with 9 rows numbered 0 .. 8 and 4 columns
-- numbered 0 .. 3. When spiro is called, it is passed the _address_ of the
-- element of params's ith row, 0th column--nothing else. Then, inside spiro,
-- the corresponding entity (also called params!) appears as a
-- _one-dimensional_ array whose 0th element shares the same address as what
-- was passed from the main program. So memory locations starting there,
-- and numbered from 0, represent the 1D array equivalent to the ith row of
-- params in the main program. Wilma, call Barney--we're programming a
-- micaprocessor here.
procedure spiro(params : Real_Matrix; row : Integer; fill : Boolean) is
NPNT : constant Integer := 2000;
xcoord, ycoord : Real_Vector(0 .. NPNT);
windings : Integer;
steps : Integer;
phi : Long_Float;
phiw : Long_Float;
dphi : Long_Float;
xmin : Long_Float;
xmax : Long_Float;
xrange_adjust : Long_Float;
ymin : Long_Float;
ymax : Long_Float;
yrange_adjust : Long_Float;
function Trunc(a : Long_Float) return Integer renames PLplot_Auxiliary.Trunc;
-- Calculate greatest common divisor following pseudo-code for the
-- Euclidian algorithm at http://en.wikipedia.org/wiki/Euclidean_algorithm
function gcd(a, b : Integer) return Integer is
t : Integer;
aa : Integer := a;
bb : Integer := b;
begin
aa := abs(aa);
bb := abs(bb);
while bb /= 0 loop
t := bb;
bb := aa mod bb;
aa := t;
end loop;
return aa;
end gcd;
begin -- spiro
-- Fill the coordinates.
-- Proper termination of the angle loop very near the beginning
-- point, see http://mathforum.org/mathimages/index.php/Hypotrochoid
windings := Trunc(abs(params(row, 1)) /
Long_Float(gcd(Trunc(params(row, 0)), Trunc(params(row, 1)))));
steps := NPNT / windings;
dphi := 2.0 * pi / Long_Float(steps);
for i in 0 .. windings * steps loop
phi := Long_Float(i) * dphi;
phiw := (params(row, 0) - params(row, 1)) / params(row, 1) * phi;
xcoord(i) := (params(row, 0)-params(row, 1))*cos(phi)+params(row, 2)*cos(phiw);
ycoord(i) := (params(row, 0)-params(row, 1))*sin(phi)-params(row, 2)*sin(phiw);
if i = 0 then
xmin := xcoord(i);
xmax := xcoord(i);
ymin := ycoord(i);
ymax := ycoord(i);
end if;
if xmin > xcoord(i) then xmin := xcoord(i); end if;
if xmax < xcoord(i) then xmax := xcoord(i); end if;
if ymin > ycoord(i) then ymin := ycoord(i); end if;
if ymax < ycoord(i) then ymax := ycoord(i); end if;
end loop;
xrange_adjust := 0.15 * (xmax - xmin);
xmin := xmin - xrange_adjust;
xmax := xmax + xrange_adjust;
yrange_adjust := 0.15 * (ymax - ymin);
ymin := ymin - yrange_adjust;
ymax := ymax + yrange_adjust;
plwind(xmin, xmax, ymin, ymax);
plcol0(1);
declare
xcoord_local, ycoord_local : Real_Vector(0 .. steps * windings);
begin
xcoord_local := xcoord(0 .. steps * windings);
ycoord_local := ycoord(0 .. steps * windings);
if fill then
plfill(xcoord_local, ycoord_local);
else
plline(xcoord_local, ycoord_local);
end if;
end;
end spiro;
procedure cycloid is
begin
null; -- TODO
end cycloid;
procedure arcs is
NSEG : constant Integer := 8;
theta : Long_Float;
dtheta : Long_Float;
a : Long_Float;
b : Long_Float;
begin
theta := 0.0;
dtheta := 360.0/Long_Float(NSEG);
plenv( -10.0, 10.0, -10.0, 10.0, 1, 0 );
-- Plot segments of circle in different colors
for i in 0 .. NSEG-1 loop
plcol0( (i mod 2) + 1 );
plarc(0.0, 0.0, 8.0, 8.0, theta, theta + dtheta, 0.0, False);
theta := theta + dtheta;
end loop;
-- Draw several filled ellipses inside the circle at different
-- angles.
a := 3.0;
b := a * tan( (dtheta/180.0*pi)/2.0 );
theta := dtheta/2.0;
for i in 0 .. NSEG-1 loop
plcol0( 2 - (i mod 2 ) );
plarc( a*cos(theta/180.0*pi), a*sin(theta/180.0*pi), a, b, 0.0, 360.0, theta, True);
theta := theta + dtheta;
end loop;
end arcs;
begin
-- Parse and process command line arguments
plparseopts(PL_PARSE_FULL);
-- Initialize plplot
plinit;
-- Illustrate the construction of a cycloid
cycloid;
-- Loop over the various curves.
-- First an overview, then all curves one by one
plssub(3, 3) ; -- Three by three window
-- Overview
fill := False;
for i in params'range(1) loop
pladv(0);
plvpor(0.0, 1.0, 0.0, 1.0);
spiro(params, i, fill);
end loop;
-- Don't fill the curves.
pladv(0) ;
plssub(1, 1) ; -- One window per curve
for i in params'range(1) loop
pladv(0) ;
plvpor(0.0, 1.0, 0.0, 1.0);
spiro(params, i, fill);
end loop;
-- Fill the curves
fill := True;
pladv(0);
plssub(1, 1); -- One window per curve
for i in params'range(1) loop
pladv(0) ;
plvpor(0.0, 1.0, 0.0, 1.0);
spiro(params, i, fill);
end loop;
arcs;
-- Don't forget to call plend to finish off!
plend;
end x27a;
|