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The teapot in PHP!
<?php
class Triangle
{
var $colors = array("yellowgreen", "tomato", "plum");
var $vertices;
function Triangle($vertices)
{
assert(sizeof($vertices) == 3);
$this->vertices = $vertices;
}
function is_right()
{
return $this->has_horizontal_leg() && $this->has_vertical_leg();
}
function has_horizontal_leg()
{
return sizeof(array_unique(array_map(function ($x) { return round($x->y, 4);}, $this->vertices))) < 3;
}
function has_vertical_leg()
{
return sizeof(array_unique(array_map(function ($x) { return round($x->x, 4);}, $this->vertices))) < 3;
}
function area()
{
return abs(
(($this->vertices[0]->x - $this->vertices[2]->x) * ($this->vertices[1]->y - $this->vertices[0]->y) -
($this->vertices[0]->x - $this->vertices[1]->x) * ($this->vertices[2]->y - $this->vertices[0]->y)) * 0.5
);
}
function max_x()
{
return max(array_map(function ($x) { return $x->x; }, $this->vertices));
}
function max_y()
{
return max(array_map(function ($x) { return $x->y; }, $this->vertices));
}
function min_x()
{
return min(array_map(function ($x) {return $x->x; }, $this->vertices));
}
function min_y()
{
return min(array_map(function ($x) { return $x->y; }, $this->vertices));
}
function vertical_cross_lines()
{
return array_map(function ($x) {
return new Line(new Point($x->x, $this->min_y()), new Point($x->x, $this->max_y()));
}, $this->vertices);
}
function horizontal_cross_lines()
{
return array_map(function ($x) {
return new Line(new Point($this->min_x(), $x->y), new Point($this->max_x(), $x->y));
}, $this->vertices);
}
function select_crossline()
{
function comp1($a, $b)
{
if ($a->a->x > $b->a->x) {
return 1;
} elseif ($a->a->x < $b->a->x) {
return -1;
} else {
return 0;
}
}
function comp2($a, $b)
{
if ($a->a->y > $b->a->y) {
return 1;
} elseif ($a->a->y < $b->a->y) {
return -1;
} else {
return 0;
}
}
if ($this->has_horizontal_leg()) {
$lines = $this->vertical_cross_lines();
usort($lines, "comp1");
} else {
$lines = $this->horizontal_cross_lines();
usort($lines, "comp2");
}
return $lines[1];
}
function split_triangle()
{
$crossline = $this->select_crossline();
assert(!is_null($crossline));
$split_vertex = array_values(array_filter($this->vertices, function ($x) use ($crossline) {
return $crossline->is_online($x);
}));
$other_vertices = array_values(array_filter($this->vertices, function ($x) use ($crossline) {
return !$crossline->is_online($x);
}));
assert(sizeof($split_vertex) == 1);
assert(sizeof($other_vertices) == 2);
assert($other_vertices[0] != $other_vertices[1]);
$cross_point = (new Line($other_vertices[0], $other_vertices[1]))->intersection_point($crossline);
$first = new Triangle(array($split_vertex[0], $cross_point, $other_vertices[0]));
$second = new Triangle(array($split_vertex[0], $cross_point, $other_vertices[1]));
return array($first, $second);
}
function svg()
{
return sprintf("<polygon points='%f,%f %f,%f %f,%f' style='fill:%s;stroke:white'/>",
$this->vertices[0]->x, $this->vertices[0]->y,
$this->vertices[1]->x, $this->vertices[1]->y,
$this->vertices[2]->x, $this->vertices[2]->y,
$this->colors[array_rand($this->colors, 1)]
);
}
}
class Point
{
var $x = 0;
var $y = 0;
function Point($x, $y)
{
$this->x = $x;
$this->y = $y;
}
}
class Line
{
var $EPSILON = 0.0001;
var $a;
var $b;
function Line($a, $b)
{
$this->a = $a;
$this->b = $b;
}
function length()
{
return (sqrt(pow(($this->b->x - $this->a->x), 2) + pow(($this->b->y - $this->a->y), 2)));
}
function linear_equation()
{
$divisor = ($this->b->x - $this->a->x);
if ($divisor != 0) {
$k = ($this->b->y - $this->a->y) / $divisor;
} else {
$k = INF;
}
$d = $this->a->y - $k * $this->a->x;
return array($k, $d);
}
function is_online($r)
{
list($slope, $intercept) = $this->linear_equation();
if (is_infinite($slope)) {
$error = $this->a->x - $r->x;
} elseif (is_infinite($intercept)) {
$error = $this->a->y - $r->y;
} else {
$error = $r->y - ($slope * $r->x + $intercept);
}
return (abs($error) < $this->EPSILON);
}
function intersection_point($other)
{
list($this_slope, $this_intercept) = $this->linear_equation();
list($other_slope, $other_intercept) = $other->linear_equation();
if (is_infinite($this_slope)) {
$x = $this->a->x;
$y = $other_slope * $x + $other_intercept;
} elseif (is_infinite($other_slope)) {
$x = $other->a->x;
$y = $this_slope * $x + $this_intercept;
} else {
$x = ($other_intercept - $this_intercept) / ($this_slope - $other_slope);
$y = $this_slope * $x + $this_intercept;
}
return new Point($x, $y);
}
}
// Load the data file
function load($file)
{
function get_triangles($acc, $line)
{
$pattern_points = '/"({.*,.*})","({.*,.*})","({.*,.*})"/';
preg_match($pattern_points, $line, $matches);
$points = array_map(function ($x) {
$pattern_point = '/{(.*),(.*)}/';
preg_match($pattern_point, $x, $matches);
return new Point(
($matches[1] * 800) + 600,
($matches[2] * -800) + 1050
);
}, array_slice($matches, 1));
if (sizeof($points) != 3)
return $acc;
$trg = new Triangle($points);
array_push($acc, $trg);
return $acc;
}
return array_reduce(file($file), "get_triangles", array());
}
function split_triangles($t)
{
if ($t->is_right() || $t->area() < 1)
return array($t);
return array_flatten(array_map(function ($trg) {return split_triangles($trg);}, $t->split_triangle()));
}
function array_flatten($arr) {
$arr = array_values($arr);
while (list($k,$v)=each($arr)) {
if (is_array($v)) {
array_splice($arr,$k,1,$v);
next($arr);
}
}
return $arr;
}
function print_err($str){
$stderr = fopen('php://stderr', 'w');
fwrite($stderr, $str);
fclose($stderr);
}
function bench($op) {
$time_start = microtime(true);
$op();
$time_end = microtime(true);
return $time_end - $time_start;
}
$file = "teapot.txt";
$triangles = load($file);
$time_start = microtime(true);
$triangles = load($file);
$time = (microtime(true) - $time_start) * 1000;
print_err("Loaded " . sizeof($triangles) . " triangles in " . $time . " ms\n");
$time_start = microtime(true);
$right_triangles = array_flatten(array_map(function ($trg) {
return split_triangles($trg);
}, $triangles));$time = microtime(true) - $time_start;
$time = (microtime(true) - $time_start) * 1000;
print_err("Generated " . sizeof($right_triangles) . " triangles in " . $time . " ms\n");
print("<svg xmlns='http://www.w3.org/2000/svg' version='1.1'>");
foreach($right_triangles as $triangle)
print($triangle->svg()."\n");
print('</svg>');
@gousiosg

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@gousiosg gousiosg commented Oct 7, 2013

The input teapot.txt file can be found here

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