// Multi-lingual version of the first page of example 4.
//
// Copyright (C) 2009 Werner Smekal
//
// Thanks to the following for providing translated strings for this example:
// Valery Pipin (Russian)
//
// 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
//
//

//
// This example designed just for devices (e.g., psttfc and the
// cairo-related devices) that use the pango and fontconfig libraries. The
// best choice of glyph is selected by fontconfig and automatically rendered
// by pango in way that is sensitive to complex text layout (CTL) language
// issues for each unicode character in this example. Of course, you must
// have the appropriate TrueType fonts installed to have access to all the
// required glyphs.
//
// Translation instructions: The strings to be translated are given by
// x_label, y_label, alty_label, title_label, and line_label below.  The
// encoding used must be UTF-8.
//
// The following strings to be translated involve some scientific/mathematical
// jargon which is now discussed further to help translators.
//
// (1) dB is a decibel unit, see http://en.wikipedia.org/wiki/Decibel .
// (2) degrees is an angular measure, see
//    http://en.wikipedia.org/wiki/Degree_(angle) .
// (3) low-pass filter is one that transmits (passes) low frequencies.
// (4) pole is in the mathematical sense, see
//    http://en.wikipedia.org/wiki/Pole_(complex_analysis) .  "Single Pole"
//    means a particular mathematical transformation of the filter function has
//    a single pole, see
//    http://ccrma.stanford.edu/~jos/filters/Pole_Zero_Analysis_I.html .
//    Furthermore, a single-pole filter must have an inverse square decline
//    (or -20 db/decade). Since the filter plotted here does have that
//    characteristic, it must by definition be a single-pole filter, see also
//    http://www-k.ext.ti.com/SRVS/Data/ti/KnowledgeBases/analog/document/faqs/1p.htm
// (5) decade represents a factor of 10, see
//    http://en.wikipedia.org/wiki/Decade_(log_scale) .
//


import std.string;
import std.math;

import plplot;

string[] x_label = [
    "Frequency",
    "Частота",
    null
];

string[] y_label = [
    "Amplitude (dB)",
    "Амплитуда (dB)",
    null
];

string[] alty_label = [
    "Phase shift (degrees)",
    "Фазовый сдвиг (градусы)",
    null
];

// Short rearranged versions of y_label and alty_label.
string[][] legend_text = [
    [ "Amplitude", "Phase shift"               ],
    [ "Амплитуда", "Фазовый сдвиг" ],
    null
];

string[] title_label = [
    "Single Pole Low-Pass Filter",
    "Однополюсный Низко-Частотный Фильтр",
    null
];

string[] line_label = [
    "-20 dB/decade",
    "-20 dB/десяток",
    null
];


//--------------------------------------------------------------------------
// main
//
// Illustration of logarithmic axes, and redefinition of window.
//--------------------------------------------------------------------------
int main( char[][] args )
{
    // Parse and process command line arguments
    plparseopts( args, PL_PARSE_FULL );

    // Initialize plplot
    plinit();
    plfont( 2 );

    // Make log plots using two different styles.
    int i = 0;
    while ( x_label[i] )
    {
        plot1( 0, x_label[i], y_label[i], alty_label[i], title_label[i], line_label[i], legend_text[i] );
        i++;
    }

    plend();
    return 0;
}

//--------------------------------------------------------------------------
// plot1
//
// Log-linear plot.
//--------------------------------------------------------------------------
void plot1( int type, string x_label, string y_label, string alty_label,
            string title_label, string line_label, string[] legend_text )
{
    // Set up data for log plot
    PLFLT[101] freql, ampl, phase;
    PLFLT    f0      = 1.0, freq;
    PLINT    nlegend = 2;
    string[] symbols;
    PLINT[]  opt_array;
    PLINT[]  text_colors;
    PLINT[]  box_colors;
    PLINT[]  box_patterns;
    PLFLT[]  box_scales;
    PLFLT[]  box_line_widths;
    PLINT[]  line_colors;
    PLINT[]  line_styles;
    PLFLT[]  line_widths;
    PLINT[]  symbol_numbers, symbol_colors;
    PLFLT[]  symbol_scales;
    PLFLT    legend_width, legend_height;

    for ( int i = 0; i < 101; i++ )
    {
        freql[i] = -2.0 + i / 20.0;
        freq     = pow( 10.0, freql[i] );
        ampl[i]  = 20.0 * log10( 1.0 / sqrt( 1.0 + pow( ( freq / f0 ), 2. ) ) );
        phase[i] = -( 180.0 / PI ) * atan( freq / f0 );
    }

    pladv( 0 );

    plvpor( 0.15, 0.85, 0.1, 0.9 );
    plwind( -2.0, 3.0, -80.0, 0.0 );

    // Try different axis and labelling styles.
    plcol0( 1 );
    switch ( type )
    {
    case 0:
        plbox( "bclnst", 0.0, 0, "bnstv", 0.0, 0 );
        break;
    case 1:
        plbox( "bcfghlnst", 0.0, 0, "bcghnstv", 0.0, 0 );
        break;
    default:
        break;
    }

    // Plot ampl vs freq
    plcol0( 2 );
    plline( freql, ampl );
    plcol0( 2 );
    plptex( 1.6, -30.0, 1.0, -20.0, 0.5, line_label );

    // Put labels on
    plcol0( 1 );
    plmtex( "b", 3.2, 0.5, 0.5, x_label );
    plmtex( "t", 2.0, 0.5, 0.5, title_label );
    plcol0( 2 );
    plmtex( "l", 5.0, 0.5, 0.5, y_label );

    // For the gridless case, put phase vs freq on same plot
    if ( type == 0 )
    {
        plcol0( 1 );
        plwind( -2.0, 3.0, -100.0, 0.0 );
        plbox( "", 0.0, 0, "cmstv", 30.0, 3 );
        plcol0( 3 );
        plline( freql, phase );
        plstring( freql, phase, "#(728)" );
        plcol0( 3 );
        plmtex( "r", 5.0, 0.5, 0.5, alty_label );
    }
    // Initialize arrays needed for pllegend.
    opt_array.length       = nlegend;
    text_colors.length     = nlegend;
    line_colors.length     = nlegend;
    line_styles.length     = nlegend;
    line_widths.length     = nlegend;
    box_colors.length      = nlegend;
    box_patterns.length    = nlegend;
    box_scales.length      = nlegend;
    box_line_widths.length = nlegend;
    symbol_numbers.length  = nlegend;
    symbol_colors.length   = nlegend;
    symbol_scales.length   = nlegend;
    symbols.length         = nlegend;

    // Draw a legend
    // First legend entry.
    opt_array[0]   = PL_LEGEND_LINE;
    text_colors[0] = 2;
    line_colors[0] = 2;
    line_styles[0] = 1;
    line_widths[0] = 1.;
    // Note from the above opt_array the first symbol (and box) indices
    // do not have to be specified

    // Second legend entry.
    opt_array[1]      = PL_LEGEND_LINE | PL_LEGEND_SYMBOL;
    text_colors[1]    = 3;
    line_colors[1]    = 3;
    line_styles[1]    = 1;
    line_widths[1]    = 1.;
    symbol_colors[1]  = 3;
    symbol_scales[1]  = 1.;
    symbol_numbers[1] = 4;
    symbols[1]        = "#(728)";
    // Note from the above opt_array the second box array indices
    // do not have to be specified

    plscol0a( 15, 32, 32, 32, 0.70 );
    pllegend( &legend_width, &legend_height,
        PL_LEGEND_BACKGROUND | PL_LEGEND_BOUNDING_BOX, 0,
        0.0, 0.0, 0.1, 15,
        1, 1, 0, 0,
        opt_array,
        1.0, 1.0, 2.0,
        1., text_colors, legend_text,
        box_colors, box_patterns, box_scales, box_line_widths,
        line_colors, line_styles, line_widths,
        symbol_colors, symbol_scales, symbol_numbers, symbols );
}