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openwrt-packages/nanonote-example-files/files/lua-plplot-examples/x19.lua

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2011-01-18 10:21:06 +02:00
--[[ $Id: x19.lua 10293 2009-08-19 07:57:43Z smekal $
Illustrates backdrop plotting of world, US maps.
Contributed by Wesley Ebisuzaki.
Copyright (C) 2008 Werner Smekal
This file is part of PLplot.
PLplot is free software you can redistribute it and/or modify
it under the terms of the GNU General Library 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
--]]
-- initialise Lua bindings for PLplot examples.
dofile("plplot_examples.lua")
--------------------------------------------------------------------------
-- mapform19
--
-- Defines specific coordinate transformation for example 19.
-- Not to be confused with mapform in src/plmap.c.
-- x[], y[] are the coordinates to be plotted.
--------------------------------------------------------------------------
function mapform19(n, x, y)
for i = 1, n do
radius = 90 - y[i]
xp = radius * math.cos(x[i] * math.pi / 180)
yp = radius * math.sin(x[i] * math.pi / 180)
x[i] = xp
y[i] = yp
end
return x, y
end
-- "Normalize" longitude values so that they always fall between
-- -180.0 and 180.0
function normalize_longitude(lon)
if lon>=-180 and lon<=180 then
return lon;
else
times = math.floor((math.abs(lon)+180)/360)
if lon<0 then
return lon+360*times
else
return lon-360*times
end
end
end
-- A custom axis labeling function for longitudes and latitudes.
function geolocation_labeler(axis, value)
if axis==pl.PL_Y_AXIS then
label_val = value
if label_val>0 then
direction_label = " N"
else
if label_val<0 then
direction_label = " S"
else
direction_label = "Eq"
end
end
else
if axis==pl.PL_X_AXIS then
label_val = normalize_longitude(value);
if label_val>0 then
direction_label = " E"
else
if label_val<0 then
direction_label = " W"
else
direction_label = ""
end
end
end
end
if axis==pl.PL_Y_AXIS and value==0 then
-- A special case for the equator
label = direction_label
else
label = math.abs(label_val) .. direction_label
end
return label
end
--------------------------------------------------------------------------
-- main
--
-- Shows two views of the world map.
--------------------------------------------------------------------------
-- Parse and process command line arguments
pl.parseopts(arg, pl.PL_PARSE_FULL)
-- Longitude (x) and latitude (y)
miny = -70
maxy = 80
pl.init()
-- Cartesian plots
-- Most of world
minx = 190
maxx = 190+360
-- Setup a custom latitude and longitude-based scaling function.
pl.slabelfunc("geolocation_labeler");
pl.col0(1)
pl.env(minx, maxx, miny, maxy, 1, 70)
pl.map(nil, "usaglobe", minx, maxx, miny, maxy)
-- The Americas
minx = 190
maxx = 340
pl.col0(1)
pl.env(minx, maxx, miny, maxy, 1, 70)
pl.map(nil, "usaglobe", minx, maxx, miny, maxy)
-- Clear the labeling function
pl.slabelfunc(nil);
-- Polar, Northern hemisphere
minx = 0
maxx = 360
pl.env(-75., 75., -75., 75., 1, -1)
pl.map("mapform19", "globe", minx, maxx, miny, maxy)
pl.lsty(2)
pl.meridians("mapform19", 10, 10, 0, 360, -10, 80)
pl.plend()