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138 lines
3.3 KiB
Lua
138 lines
3.3 KiB
Lua
--[[ $Id: x30.lua 10668 2009-12-02 08:38:49Z airwin $
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Alpha color values demonstration.
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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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red = { 0, 255, 0, 0 }
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green = { 0, 0, 255, 0 }
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blue = { 0, 0, 0, 255 }
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alpha = { 1, 1, 1, 1 }
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px = { 0.1, 0.5, 0.5, 0.1 }
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py = { 0.1, 0.1, 0.5, 0.5 }
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pos = { 0, 1 }
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rcoord = { 1, 1 }
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gcoord = { 0, 0 }
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bcoord = { 0, 0 }
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acoord = { 0, 1 }
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rev = { 0, 0 }
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pl.parseopts (arg, pl.PL_PARSE_FULL);
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pl.init()
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pl.scmap0n(4)
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pl.scmap0a(red, green, blue, alpha)
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-- Page 1:
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--
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-- This is a series of red, green and blue rectangles overlaid
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-- on each other with gradually increasing transparency.
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-- Set up the window
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pl.adv(0)
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pl.vpor(0, 1, 0, 1)
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pl.wind(0, 1, 0, 1)
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pl.col0(0)
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pl.box("", 1, 0, "", 1, 0)
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-- Draw the boxes
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for i = 0, 8 do
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icol = math.mod(i, 3) + 1
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-- Get a color, change its transparency and
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-- set it as the current color.
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r, g, b, a = pl.gcol0a(icol)
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pl.scol0a(icol, r, g, b, 1-i/9)
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pl.col0(icol)
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-- Draw the rectangle
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pl.fill(px, py)
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-- Shift the rectangles coordinates
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for j = 1, 4 do
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px[j] = px[j] + 0.5/9
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py[j] = py[j] + 0.5/9
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end
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end
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-- Page 2:
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-- This is a bunch of boxes colored red, green or blue with a single
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-- large (red) box of linearly varying transparency overlaid. The
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-- overlaid box is completely transparent at the bottom and completely
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-- opaque at the top.
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-- Set up the window
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pl.adv(0)
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pl.vpor(0.1, 0.9, 0.1, 0.9)
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pl.wind(0.0, 1.0, 0.0, 1.0)
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-- Draw the boxes. There are 25 of them drawn on a 5 x 5 grid.
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for i = 0, 4 do
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-- Set box X position
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px[1] = 0.05 + 0.2 * i
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px[2] = px[1] + 0.1
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px[3] = px[2]
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px[4] = px[1]
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-- We don't want the boxes to be transparent, so since we changed
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-- the colors transparencies in the first example we have to change
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-- the transparencies back to completely opaque.
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icol = math.mod(i, 3) + 1
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r, g, b, a = pl.gcol0a(icol)
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pl.scol0a(icol, r, g, b, 1)
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pl.col0(icol)
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for j = 0, 4 do
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-- Set box y position and draw the box.
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py[1] = 0.05 + 0.2 * j
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py[2] = py[1]
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py[3] = py[1] + 0.1
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py[4] = py[3]
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pl.fill(px, py)
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end
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end
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-- Create the color map with 128 colors and use plscmap1la to initialize
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-- the color values with a linearly varying red transparency (or alpha)
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pl.scmap1n(128)
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pl.scmap1la(1, pos, rcoord, gcoord, bcoord, acoord, rev)
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-- Use that cmap1 to create a transparent red gradient for the whole
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-- window.
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px[1] = 0.
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px[2] = 1.
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px[3] = 1.
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px[4] = 0.
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py[1] = 0.
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py[2] = 0.
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py[3] = 1.
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py[4] = 1.
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pl.gradient(px, py, 90.)
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pl.plend()
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