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130 lines
3.1 KiB
Lua
130 lines
3.1 KiB
Lua
--[[ $Id: x27.lua 9526 2009-02-13 22:06:13Z smekal $
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Drawing "spirograph" curves - epitrochoids, cycolids, roulettes
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Copyright (C) 2009 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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function cycloid()
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-- TODO
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end
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function spiro( params )
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NPNT = 20000
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xcoord = {}
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ycoord = {}
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-- Fill the coordinates
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windings = params[4]
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steps = math.floor(NPNT/windings)
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dphi = 8*math.acos(-1)/steps
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xmin = 0 -- This initialisation is safe!
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xmax = 0
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ymin = 0
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ymax = 0
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for i = 1, windings*steps+1 do
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phi = (i-1) * dphi
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phiw = (params[1]-params[2])/params[2]*phi
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xcoord[i] = (params[1]-params[2])*math.cos(phi) + params[3]*math.cos(phiw)
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ycoord[i] = (params[1]-params[2])*math.sin(phi) - params[3]*math.sin(phiw)
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if xmin>xcoord[i] then xmin = xcoord[i] end
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if xmax<xcoord[i] then xmax = xcoord[i] end
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if ymin>ycoord[i] then ymin = ycoord[i] end
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if ymax<ycoord[i] then ymax = ycoord[i] end
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end
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if (xmax-xmin)>(ymax-ymin) then
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scale = xmax - xmin
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else
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scale = ymax - ymin
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end
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xmin = -0.65*scale
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xmax = 0.65*scale
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ymin = -0.65*scale
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ymax = 0.65*scale
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pl.wind(xmin, xmax, ymin, ymax)
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pl.col0(1)
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pl.line(xcoord, ycoord)
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end
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----------------------------------------------------------------------------
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-- main
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--
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-- Generates two kinds of plots:
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-- - construction of a cycloid (animated)
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-- - series of epitrochoids and hypotrochoids
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----------------------------------------------------------------------------
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-- R, r, p, N
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params = {
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{ 21, 7, 7, 3 }, -- Deltoid
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{ 21, 7, 10, 3 },
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{ 21, -7, 10, 3 },
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{ 20, 3, 7, 20 },
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{ 20, 3, 10, 20 },
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{ 20, -3, 10, 20 },
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{ 20, 13, 7, 20 },
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{ 20, 13, 20, 20 },
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{ 20,-13, 20, 20 } }
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-- plplot initialization
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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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-- Initialize plplot
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pl.init()
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-- Illustrate the construction of a cycloid
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cycloid()
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-- Loop over the various curves
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-- First an overview, then all curves one by one
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pl.ssub(3, 3) -- Three by three window
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for i = 1, 9 do
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pl.adv(0)
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pl.vpor(0, 1, 0, 1)
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spiro(params[i])
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end
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pl.adv(0)
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pl.ssub(1, 1) -- One window per curve
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for i = 1, 9 do
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pl.adv(0)
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pl.vpor(0, 1, 0, 1)
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spiro(params[i])
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end
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-- Don't forget to call plend() to finish off!
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pl.plend()
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