Exploded 3D pie graph showing side shading

The code below is the source for this graph.

<?php
// Exploded 3D pie graph showing side shading
require_once 'SVGGraph/autoloader.php';

$settings = [
  'back_stroke_width' => 0,
  'auto_fit' => true,
  'structure' => [
    'key' => 0,
    'value' => 1,
    'explode' => 2,
  ],
  'explode' => 'none',
  'explode_amount' => 50,
  'data_label_font_size' => 20,
  'data_label_font_weight' => 'bold',
  'data_label_type' => 'box',
  'data_label_outline_colour' => 'fillColour/brightness(0.6)',
  'data_label_outline_thickness' => 2,
  'data_label_round' => 4,
  'data_label_colour' => 'fillColour/brightness(0.6)',
  'data_label_padding' => 6,
  'sort' => false,
  'aspect_ratio' => 'auto',
  'start_angle' => 120,
  'end_angle' => 60,
  'depth_shade_gradient' => ['black:0.9', 'yellow:0.1', 'black:0.9', 'h'],
];

$type = 'ExplodedPie3DGraph';

$values = [
  ['Tea', 10, 0.7],
  ['Coffee', 20, 1.0],
  ['Milk', 25, 0.5],
  ['Water', 50],
];

$colours = ['#e97','#630','#edd', ['#6bf','pattern' => 'polkadot2']];

$graph = new Goat1000\SVGGraph\SVGGraph(670, 300, $settings);
$graph->colours($colours);
$graph->values($values);
$graph->render($type);

Please note: the source code above comes from a script used to generate one of the example graphs on the site. This is simply a wrapper page to apply highlighting and make the source code easier to read, so there is no content here to describe what the source code is doing.