$width = 500;
$height = 500;
$im = imagecreatetruecolor($width, $height);
$red = imagecolorallocate($im, 230, 0, 0);
imagefill($im, 0, 0, $red);
$yellow = imagecolorallocate($im, 255, 255, 0);
//设定画出五角星的五个顶点形成的 正五边形的边长
$b=100;
$pi=3.14/180;
$p1x = 150;
$p1y = 250;
$p2x = 150+(cos(36*$pi)*$b);
$p2y = 250-(sin(36*$pi)*$b);
$p3x = 150+(2*cos(36*$pi)*$b);
$p3y = 250;
$p4x = $p3x-sin(18*$pi)*$b;
$p4y = 250+cos(18*$pi)*$b;
$p5x = 150+sin(18*$pi)*$b;
$p5y = 250+cos(18*$pi)*$b;
//连接相应的点 画线
imageline($im, $p1x, $p1y, $p3x, $p3y, $yellow);
imageline($im, $p1x, $p1y, $p4x, $p4y, $yellow);
imageline($im, $p2x, $p2y, $p4x, $p4y, $yellow);
imageline($im, $p2x, $p2y, $p5x, $p5y, $yellow);
imageline($im, $p3x, $p3y, $p5x, $p5y, $yellow);
header('Content-Type:image/png');
imagepng($im);
imagedestroy($im);
?>