<?
/* ****************************************************
STAR - class and example to generate a sky of stars
Written By: Ronnie Schwartz <ronnie@rustybrick.com>
3/2001
****************************************************
*/
header("Content-type: image/jpeg");
// CONSTANTS
//
$AMT_STARS = 40; // how many stars do you want
$APP_WIDTH = 150; // width of the applet
$APP_HEIGHT = 150; // height of the applet
srand((double)microtime()*1000000); // init random generator
$im = imagecreate ($APP_WIDTH, $APP_HEIGHT);
$black = ImageColorAllocate ($im, 0, 0, 0);
ImageRectangle($im, 0, 0, $APP_WIDTH, $APP_HEIGHT, $black); // set the background to black (starfield)
// produce AMT_STARS stars at random locations, sizes and shapes
//
for ($x=0; $x<$AMT_STARS; $x++) {
$x_offset = rand(0,$APP_WIDTH);
$y_offset = rand(0,$APP_HEIGHT);
$radius = rand(1,$APP_WIDTH/10);
$points = rand(4,8);
$myStar = new Star($radius,$points); // init star object
$myStar->generateStar($x_offset,$y_offset,$im); // generate star
}
ImageJpeg($im,'',100);
//***********************************************************************//
// Star - used to generate a star, given the radius and amount of points //
//***********************************************************************//
class Star
{
var $radius; // radius of the star
var $amtPoints; // amount of points
var $amtSides; // amount of sides (points * 2)
// Constructor - sets the radius, amtPoints and amtSides variables
//
function Star($r, $n)
{
$this->radius = $r;
$this->amtPoints = $n;
$this->amtSides = $this->amtPoints * 2;
}
// Generates a star given the location of the star and the graphics object to paint on
//
function generateStar($x_offset, $y_offset, &$img)
{
$pointA=0; // used to count the point number from 0 to amtPoints-1 - for outside points
$pointB=0; // used to count the point number from 0 to amtPoints-1 - for inside points
for ($i=0; $i<$this->amtSides; $i++) {
if ($i % 2 == 0) { // even = outside points
$x_coords[$i] = $this->getX($this->amtPoints, $pointA, $this->radius, $x_offset, 0.0);
$y_coords[$i] = $this->getY($this->amtPoints, $pointA, $this->radius, $y_offset, 0.0);
$pointA++;
}
else { // odd = inside points
$x_coords[$i] = $this->getX($this->amtPoints, $pointB, $this->radius/2, ($this->radius/2) + $x_offset, 0.5);
$y_coords[$i] = $this->getY($this->amtPoints, $pointB, $this->radius/2, ($this->radius/2) + $y_offset, 0.5);
$pointB++;
}
}
// merge the x_coords and y_coords array into one
$point = 0;
for ($i=0; $i<$this->amtSides*2; $i+=2) {
$coords[$i] = $x_coords[$point];
$coords[$i+1] = $y_coords[$point];
$point++;
}
$white = ImageColorAllocate ($img, 255, 255, 255); // set stars color to white
imageFilledPolygon($img, $coords, $this->amtSides, $white); // paint the star
}
// Two methods that get the x and y coordinates of a circle given the following information:
// totalPoints - the total amount of points to generate on a circumference
// pointNum - the number of the point you want to get (0 to totalPoints-1)
// radius - the radius of the circle
// offset - the amount of pixels the point should be offset
// rotate - the amount to rotate the circle (needed to draw inner circle and make star)
// getX - generates x coordinates using cos()
function getX($totalPoints, $pointNum, $radius, $offset, $rotate)
{
$PI = 3.14;
return (int) (cos( 2 * $PI * ($pointNum + $rotate) / $totalPoints) * $radius ) + $radius + $offset;
}
// getY - generates y coordinates using sin()
function getY($totalPoints, $pointNum, $radius, $offset, $rotate)
{
$PI = 3.14;
return (int) (sin( 2 * $PI * ($pointNum + $rotate) / $totalPoints) * $radius ) + $radius + $offset;
}
}
?>
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