Captcha 3d

After reading the topic "RapidShare - new captcha" , I remembered listening to the report of the creator of the captcha on UaWeb.



Having visited the site, wanting to see the code, I saw:
Q: Is it opensource?
A: No, sorry. Maybe later.
')
I was surprised ! It seemed to me that any poorly educated good programmer would make such a captcha.
Googling and found a couple of interesting links: 1 , 2 and did not receive the code, I decided to write myself.

: 00 How to start? Recalling the times of the university, linear analysis (I was led by a very good teacher ) and thinking what to do gently with 3D -> 2D, and this, as I remember, is called “projection”, I typed this word in the search bar
: 03 After following the chain of links in Wikipedia and reading a suitable article, I decided that an isometric projection would suit me
: 05 Well, the main formula is

: 15 a couple of lines of code and here is the first 3D image

: 16 two cycles and

: 20 I will display the text and using it as a pattern for the z axis we get

: 30 add noise and sine waves get


Speed draw rate 31.42 [# / sec] on Intel Core 2 Duo 2.2 GGz php 5.2.6 Apache 2.2.4 on Win Vista Sp1

/**
*
* @author Andrii Kasian <to.kandy@gmail.com>
*/

<?php


$capthca = new Capthca3d ();

$capthca -> render ();



class Capthca3d {


const CHARS = 'WEafRTYIPAGHJKXBNM3479j' ;

protected $hypot = 8 ;

protected $image = null ;



protected $text = '' ;




public function __construct ()

{

$this -> time = microtime ( true );

$this -> generateCode ();




}

protected function generateCode ()

{

$chars = self :: CHARS ;

for( $i = 0 ; $i < 3 ; $i ++){


$this -> text .= $chars { mt_rand ( 0 , 22 )};

}

}



public function getText ()


{

return $this -> text ;

}

protected function getProection ( $x1 , $y1 , $z1 )


{

$x = $x1 * $this -> hypot ;

$y = $z1 * $this -> hypot ;


$z = - $y1 * $this -> hypot ;



$xx = 0.707106781187 ;

$xy = 0 ;


$xz = - 0.707106781187 ;



$yx = 0.408248290464 ;

$yy = 0.816496580928 ;


$yz = 0.408248290464 ;



$cx = $xx * $x + $xy * $y + $xz * $z ;


$cy = $yx * $x + $yy * $y + $yz * $z + 20 * $this -> hypot ;


return array(

'x' => $cx ,

'y' => $cy

);

}



function zFunction ( $x , $y ){


$z = imagecolorat ( $this -> image , $y / 2 , $x / 2 )> 0 ? 2.6 : 0 ;


if( $z != 0 ){

$z += mt_rand ( 0 , 60 )/ 100 ;

}

$z += 1.4 * sin (( $x + $this -> startX )* 3.141592654 / 15 )* sin (( $y + $this -> startY )* 3.141592654 / 15 );


return $z ;

}

public function render ()

{

$xx = 30 ;

$yy = 60 ;




$this -> image = imageCreateTrueColor ( $yy * $this -> hypot , $xx * $this -> hypot );




$whiteColor = imageColorAllocate ( $this -> image , 255 , 255 , 255 );

imageFilledRectangle ( $this -> image , 0 , 0 , $yy * $this -> hypot , $xx * $this -> hypot , $whiteColor );




$textColor = imageColorAllocate ( $this -> image , 0 , 0 , 0 );

imageString ( $this -> image , 5 , 3 , 0 , $this -> text , $textColor );






$this -> startX = mt_rand ( 0 , $xx );

$this -> startY = mt_rand ( 0 , $yy );




$coordinates = array();



for( $x = 0 ; $x < $xx + 1 ; $x ++){


for( $y = 0 ; $y < $yy + 1 ; $y ++){

$coordinates [ $x ][ $y ] = $this -> getProection ( $x , $y , $this -> zFunction ( $x , $y ));


}

}



for( $x = 0 ; $x < $xx ; $x ++){

for( $y = 0 ; $y < $yy ; $y ++){


$coord = array();

$coord [] = $coordinates [ $x ][ $y ][ 'x' ];

$coord [] = $coordinates [ $x ][ $y ][ 'y' ];




$coord [] = $coordinates [ $x + 1 ][ $y ][ 'x' ];

$coord [] = $coordinates [ $x + 1 ][ $y ][ 'y' ];




$coord [] = $coordinates [ $x + 1 ][ $y + 1 ][ 'x' ];

$coord [] = $coordinates [ $x + 1 ][ $y + 1 ][ 'y' ];




$coord [] = $coordinates [ $x ][ $y + 1 ][ 'x' ];

$coord [] = $coordinates [ $x ][ $y + 1 ][ 'y' ];




$c = (int) ( $this -> zFunction ( $x , $y )* 32 );

$linesColor = imageColorAllocate ( $this -> image , $c , $c , $c );


imageFilledPolygon ( $this -> image , $coord , 4 , $whiteColor );

imagePolygon ( $this -> image , $coord , 4 , $linesColor );


}

}



$textColor = imageColorAllocate ( $this -> image , 0 , 0 , 0 );


imageString ( $this -> image , 5 , 3 , 0 , $this -> text , $whiteColor );


imageString ( $this -> image , 1 , 3 , 0 , ( microtime ( true )- $this -> time ), $textColor );


header ( 'Content-Type: image/png' );



imagepng ( $this -> image );

imagedestroy ( $this -> image );


}

}





PS: GPL