<?  

/* ****************************************************
   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
//HEIGHT AND WIDTH OF BACKGROUND
    $APP_WIDTH  = 560;            // width of the applet
    $APP_HEIGHT = 350;            // height of the applet
        
    srand((double)microtime()*1000000);  // init random 
    
    $im = imagecreate ($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);

//CHANGE SIZE OF STARS BY CHANGING WIDTH/22
        $radius   = rand(1,$APP_WIDTH/30);
        $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 radius, amtPoints,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;
    }
}

?>