<?php
    function coordY($coord) {
        return 800 - intval((floatval($coord) + 100) * 4);
    }

    function coordX($coord) {
        return intval((floatval($coord) + 100) * 4);
    }

    $link = mysql_connect("localhost", "rk6stud", "rk6stud")
        or die("Could not connect : " . mysql_error());
    /* Выбор БД my_database */
    mysql_select_db("femdb") or die("Could not select database");

    /* Выполнение SQL-запроса */
    $query = "SELECT * FROM nodes";
    $result = mysql_query($query) or die("Query failed : " . mysql_error());

    $nodes = array();
    while ($line = mysql_fetch_array($result, MYSQL_ASSOC))
        $nodes[$line["id"]] = $line;

    mysql_free_result($result);

    /* Выполнение SQL-запроса */
    $query = "SELECT * FROM elements";
    $result = mysql_query($query) or die("Query failed : " . mysql_error());

    $elements = array();
    while ($line = mysql_fetch_array($result, MYSQL_ASSOC))
        array_push($elements, $line);

    mysql_free_result($result);
    mysql_close($link);


/*###########################################################################*/
//    var_dump($nodes);
//    var_dump($elements);
    header("Content-type: image/png");

    $img = @imagecreate(800, 800)
        or die("Cannot Initialize new GD image stream");

    $background_color = imagecolorallocate($img, 255, 255, 255);
    $point_color_pink = imagecolorallocate($img, 255, 20, 147);
    $point_color = imagecolorallocate($img, 0, 0, 0);

    $i = 0;
    foreach ($elements as $el) {
        $color = $point_color;
        if (($i % 2) == 0)
            $color = $point_color_pink;

        imageline($img, coordX($nodes[$el["n1"]]["x"]), coordY($nodes[$el["n1"]]["y"]), coordX($nodes[$el["n2"]]["x"]), coordY($nodes[$el["n2"]]["y"]), $color);
        imageline($img, coordX($nodes[$el["n2"]]["x"]), coordY($nodes[$el["n2"]]["y"]), coordX($nodes[$el["n3"]]["x"]), coordY($nodes[$el["n3"]]["y"]), $color);
        imageline($img, coordX($nodes[$el["n3"]]["x"]), coordY($nodes[$el["n3"]]["y"]), coordX($nodes[$el["n1"]]["x"]), coordY($nodes[$el["n1"]]["y"]), $color);
        $i++;
    }

    imagepng($img);
    imagedestroy($img);
?>