rotation - 3D projection to screen PHP -

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i trying 3d object position on screen.

i have studied wiki atricle https://en.wikipedia.org/wiki/3d_projection (and many others) seems getting incorrect answers.

$center =array(0,0,0); $point = array(0, 30, 30); $rot = array(90,0,0); $a=array(     array(             1,             0,             0),     array(             0,  cos($rot[0]),  sin($rot[0])),     array(             0, -sin($rot[0]),  cos($rot[0])) ); $b=array(     array(  cos($rot[1]),             0, -sin($rot[1])),     array(             0,             1,             0),     array(  sin($rot[1]),             0,  cos($rot[1])) ); $c=array(     array(  cos($rot[2]),  sin($rot[2]),             0),     array( -sin($rot[2]),  cos($rot[2]),             0),     array(             0,             0,             1) ); $a=array(     array($point[0]),     array($point[1]),     array($point[2]) ); $help = matrixmult(matrixmult($a,$b),$c); $c = matrixmult($help, $a); var_dump($c);  function matrixmult($m1,$m2){     $r=count($m1);     $c=count($m2[0]);     $p=count($m2);     if(count($m1[0])!=$p){throw new exception('incompatible matrixes');}     $m3=array();     ($i=0;$i< $r;$i++){         for($j=0;$j<$c;$j++){             $m3[$i][$j]=0;             for($k=0;$k<$p;$k++){                 $m3[$i][$j]+=$m1[$i][$k]*$m2[$k][$j];             }         }     }     return($m3); }

matrixmulti function got online , tested correct answer when multipling matrices (answers correct) , getting :

array(3) {   [0]=>   array(1) {     [0]=>     float(0)   }   [1]=>   array(1) {     [0]=>     float(13.377691424142)   }   [2]=>   array(1) {     [0]=>     float(-40.262108391892)   } }

but seems incorrect answer, since point on y,z plane , rotating x 90 degrees should give me answer (0,30,-30) or (0,-30,30) depending on sign. wrong somewhere or missing?

php trigonometric functions take angles in radians not degrees, case in majority of languages.

$rot = array(90,0,0);

should be:

$rot = array(m_pi/2,0,0);

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