<?php
  // ------------------------------------------------
  // ------------------------------------------------
  // Include the CONREC library - this assumes the two scripts are side by side on the server.
  // ------------------------------------------------
  include('conrec.inc.php');
  // ------------------------------------------------

  // ------------------------------------------------
  // Show a couple of examples
  // ------------------------------------------------
  // Use of the 'eval' function here is for convenience - general use can not be recommended.
  // ------------------------------------------------
  
  $examples = array();
  // ------------------------------------------------
  $examples[] = array('nc' => 10,
                      'x_min' => -3 * pi(),
                      'x_range' => 6 * pi(),
                      'y_min' => -3 * pi(),
                      'y_range' => 6 * pi(),
                      'string' => 'f = X.(sin(X) + sin(Y))',
                      'eval' => '$val = $x_val * (sin($x_val) + sin($y_val));');
  // ------------------------------------------------
  $examples[] = array('nc' => 10,
                      'x_min' => -1 * pi(),
                      'x_range' => 4 * pi(),
                      'y_min' => -2 * pi(),
                      'y_range' => 4 * pi(),
                      'string' => 'f =  sin((X^2 + Y^2)^0.5)',
                      'eval' => '$val = sin(pow($x_val*$x_val + $y_val*$y_val,0.5));');
  // ------------------------------------------------
  $examples[] = array('nc' => 15,
                      'x_min' => -5,
                      'x_range' => 15,
                      'y_min' => -2 * pi(),
                      'y_range' => 4 * pi(),
                      'string' => 'f =  ContouringPaper[Figure18.6]',
                      'eval' => '$val = sin(pow($x_val*$x_val + $y_val*$y_val,0.5)) + (1 / (pow(pow($x_val - 5,2) + $y_val*$y_val,0.5)));');
  // ------------------------------------------------
  $examples[] = array('nc' => 6,
                      'x_min' => 0,
                      'x_range' => 10,
                      'y_min' => 0,
                      'y_range' => 10,
                      'string' => 'f = random(0,100)',
                      'eval' => '$val = rand(0,100);');
  // ------------------------------------------------
                      
  // ------------------------------------------------
  // ------------------------------------------------
  
  $N = 100;
  $img_size = 900;  // The pixel size of the outputted image: be aware of reduced contour quality due to oversampling, keep $N <= ($img_size / 3)

  // ------------------------------------------------
  // ------------------------------------------------
    
  foreach($examples as $ex) {
  
    $d = array();
    $x = array();
    $y = array();
    
    $x_min = $ex['x_min'];
    $y_min = $ex['y_min'];
    
    $x_range = $ex['x_range'];
    $y_range = $ex['y_range'];
    
    // ------------------------------------------------
    // ------------------------------------------------
    // Create the sampled data based on the function chosen
    
    for($i = 0;$i < $N;$i++) {
      for($j = 0;$j < $N ;$j++) {
        // x
        $x_val = $x_min + ($x_range * $i / ($N - 1));
        // y
        $y_val = $y_min + ($y_range * $j / ($N - 1));
        
        // val (from eval)        
        $val = 0;
        eval($ex['eval']);
        $error = error_get_last();
        print_r($error);
    
        // Null or NaN check (crude!)
        if (!$val) { $val = 0; }
        
        $x[$i] = $x_val;
        $y[$j] = $y_val;
        $d[$i][$j] = $val;
      }
    }
    // ------------------------------------------------
  
    // ------------------------------------------------
    // ------------------------------------------------
    // INVOKE CONREC
    // ------------------------------------------------
    $contours = CONREC_contour($d,$x,$y,$ex['nc']);
    // ------------------------------------------------ 
    // ------------------------------------------------
      
    // ------------------------------------------------
    // ------------------------------------------------
    // Create output image using GD
    // ------------------------------------------------
    
    if (!function_exists('imagecreatetruecolor')) { die('Fatal error: no GD module support. Please enable this in php.ini to use this script.'); }
      
    $img = imagecreatetruecolor($img_size,$img_size);
    $white = imagecolorallocate($img,255,255,255);
    $black = imagecolorallocate($img,0,0,0);
    imagefilledrectangle($img,0,0,$img_size,$img_size,$white);
      
    // ------------------------------------------------
    $num_contours = count($contours);
    
    $R_base = rand(0,255);
    $G_base = rand(0,255);
    $B_base = rand(0,255);
    
    foreach($contours as $index=>$c) {
      // make a colour
      $R = $R_base + ((255 - $R_base) * ($index / $num_contours));
      $G = $G_base * ($index / $num_contours);
      $B = $B_base - ($B_base * ($index / $num_contours));
      
      $this_contour = imagecolorallocate($img,$R,$G,$B);
      
      // ---
      foreach($c['segments'] as $sgm) {
        // Convert X and Y to pixels
        $x1 = (($sgm['x1'] - $x_min) / $x_range) * $img_size;
        $x2 = (($sgm['x2'] - $x_min) / $x_range) * $img_size;
        
        $y1 = $img_size - (($sgm['y1'] - $y_min) / $y_range) * $img_size;
        $y2 = $img_size - (($sgm['y2'] - $y_min) / $y_range) * $img_size;
        
        imageline($img,$x1,$y1,$x2,$y2,$this_contour);
        
      }
      // ---
      
      imagefilledrectangle($img,0,($index + 1) * 20,20,($index+2)*20,$this_contour);
      
      imagerectangle($img,0,($index + 1)*20,20,($index + 2)*20,$black);
      imagestring($img,2,25,(($index + 1) * 20)+3,round($c['value'],3),$black);
      
    }
    // ------------------------------------------------
    // Label the function
    imagefilledrectangle($img,0,0,300,19,$white);
    imagestring($img,2,3,3,$ex['string'],$black);
    // ------------------------------------------------
    
    
    // ------------------------------------------------
    // Output PNG file to browser
    // ------------------------------------------------
    ob_start();
    imagepng($img);
    $image_data = ob_get_contents();
    ob_end_clean();
    imagedestroy($img);

    // Base64 encode (for embedded URI scheme)
    $image_data = base64_encode($image_data);
    
    print('<hr />');
    print('<h1>'.$ex['string'].'</h1>');
    print('<img style="border:1px solid #555;text-align:padding:1em;" src="data:image/png;base64,'.$image_data.'" />');
    print('<p>X Axis: '.round($x_min,3).' to '.round($x_min + $x_range,3).', Y Axis: '.round($y_min,3).' to '.round($y_min + $y_range,3).'</p>');

    // ------------------------------------------------
  } // end of major example loop
?>
<hr />
<p><i>End of CONREC demonstrations.</i></P>
<hr />

<hr />
<h1>CONREC PHP File</h1>
<p>The library code is shown below.</p>
<hr />
<pre>
<?php
  $file = str_replace(array('<','>'),array('<','>'),file_get_contents('conrec.inc.php'));
  print($file);
?>
</pre>

<hr />
<h1>Test PHP File (This File)</h1>
<p>The test generation code (this file) is shown below.</p>
<hr />
<pre>
<?php
  $file = str_replace(array('<','>'),array('<','>'),file_get_contents('index.php'));
  print($file);
?>