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106 lines
2.5 KiB
Lua
106 lines
2.5 KiB
Lua
--[[ $Id: x03.lua 10613 2009-11-19 12:05:09Z andrewross $
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Polar plot demo.
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Copyright (C) 2008 Werner Smekal
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This file is part of PLplot.
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PLplot is free software you can redistribute it and/or modify
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it under the terms of the GNU General Library Public License as published
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by the Free Software Foundation either version 2 of the License, or
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(at your option) any later version.
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PLplot is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Library General Public License for more details.
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You should have received a copy of the GNU Library General Public License
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along with PLplot if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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--]]
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-- initialise Lua bindings for PLplot examples.
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dofile("plplot_examples.lua")
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----------------------------------------------------------------------------
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-- main
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--
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-- Generates polar plot, with 1-1 scaling.
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----------------------------------------------------------------------------
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x0 = {}
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y0 = {}
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x = {}
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y = {}
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dtr = math.pi/180
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for i = 1, 361 do
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x0[i] = math.cos(dtr * (i-1))
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y0[i] = math.sin(dtr * (i-1))
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end
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-- Parse and process command line arguments
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pl.parseopts(arg, pl.PL_PARSE_FULL)
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-- Set orientation to portrait - note not all device drivers
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-- support this, in particular most interactive drivers do not
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pl.sori(1)
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-- Initialize plplot
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pl.init()
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-- Set up viewport and window, but do not draw box
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pl.env(-1.3, 1.3, -1.3, 1.3, 1, -2)
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-- Draw circles for polar grid
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for i = 1, 10 do
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pl.arc(0, 0, 0.1*i, 0.1*i, 0, 360, 0);
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end
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pl.col0(2)
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for i=1, 12 do
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theta = 30 * (i-1)
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dx = math.cos(dtr * theta)
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dy = math.sin(dtr * theta)
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-- Draw radial spokes for polar grid
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pl.join(0, 0, dx, dy)
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-- Write labels for angle
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if theta < 9.99 then
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offset = 0.45
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else
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if theta < 99.9 then
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offset = 0.30
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else
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offset = 0.15
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end
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end
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-- Slightly off zero to avoid floating point logic flips at 90 and 270 deg.
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if dx >= -0.00001 then
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pl.ptex(dx, dy, dx, dy, -offset, tostring(math.floor(theta)))
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else
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pl.ptex(dx, dy, -dx, -dy, 1.+offset, tostring(math.floor(theta)))
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end
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end
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-- Draw the graph
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for i=1, 361 do
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r = math.sin(dtr * (5*(i-1)))
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x[i] = x0[i] * r
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y[i] = y0[i] * r
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end
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pl.col0(3)
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pl.line(x, y)
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pl.col0(4)
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pl.mtex("t", 2, 0.5, 0.5, "#frPLplot Example 3 - r(#gh)=sin 5#gh")
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-- Close the plot at end
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pl.plend()
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