3D imaging - warping

<?php
function minAngle($line, $p){
    //$l1 and $l2 are the start and end points of a line segment, formatted as (x, y, z). $p is the points that is being tested.
    /*I'm thinking screw it. Instead of finding the minimum distance between the ray and the point. I think that I should focus on whether or not the angle between the ray and the point is satisfactory. For starters, I'll make the angular limit 1 degree.*/
    $b = pow($line['x'][1]-$line['x'][2], 2)+pow($line['y'][1]-$line['y'][2], 2)+pow($line['z'][1]-$line['z'][2], 2); //Difference between the two points of the line
    $c = pow($line['x'][1]-$p['x'], 2)+pow($line['y'][1]-$p['y'], 2)+pow($line['z'][1]-$p['z'], 2); //Difference between the start of the line and the point
    $a = pow($p['x']-$line['x'][2], 2)+pow($p['y']-$line['y'][2], 2)+pow($p['z']-$line['z'][2], 2); //difference between the end of the line and the point
    $angle = rad2deg(acos(($b+$c-$a)/(2*sqrt($b)*sqrt($c)))); //cos^(-1)((b^2 + c^2 - a^2) / 2bc), will give the angle between the point an the ray.
    if($angle < 2){
        return true;
    }else{
        return false;
    }
}

$screen_dimensions = array('height' => 700, 'width' => 700);
$screen_position = array('x' => 0, 'y' => 0, 'z' => 0);
$screen_viewingAngle = 150;
/* Do not use these yet.
$screen_yaw = 0;
$screen_pitch = 0;
$screen_roll = 0;
*/
/* BEGIN MAIN PROGRAM */
//Build screen rays
$offset['y'] = (0.5*$screen_dimensions['width'])/tan(deg2rad(0.5*$screen_viewingAngle));
$offset['x'] = 0.5*$screen_dimensions['width'];
$offset['z'] = 0.5*$screen_dimensions['height'];

$current['z'] = 0.5*$screen_dimensions['height'];
$current['x'] = -0.5*$screen_dimensions['width'];
for($i = 0; $i < 36; $i++){
    if($i > 0){
        $current['x'] += $screen_dimensions['width']/5;
    }
    if($current['x'] > $offset['x']){
        $current['x'] = -$offset['x'];
        $current['z'] -= $screen_dimensions['height']/5;
    }
    print "Z = ".$current['z'] ." X = ".$current['x'] ."</br>\n";
    $points[$i]['x'] = $current['x'];
    $points[$i]['y'] = $offset['y']+10;
    $points[$i]['z'] = $current['z'];
}
$current['z'] = 0.5*$screen_dimensions['height'];
$current['x'] = -0.5*$screen_dimensions['width'];

unlink("image.ppm"); //file that we will be editing, we are are deleting the file so we have a clean file to work on
$fh = fopen("image.ppm", 'a+'); //creates the image file that we will be editting and opens the file for appending

$print_height = 1+$screen_dimensions['height'];
$print_width = 1+$screen_dimensions['width'];

$startWrite = "P3\n# image.ppm\n$print_width $print_height\n255"; //fomatting the ppm file
fwrite($fh, $startWrite);

for($i = 0; $i < ($print_height*$print_width); $i++){
    //Origin points
    $lines['x'][1] = $screen_position['x'];
    $lines['y'][1] = $screen_position['y'];
    $lines['z'][1] = $screen_position['z'];
    // \Origin points
    //To points
    if($i > 0){
        $current['x']++;
    }
    if($current['x'] > $offset['x']){
        $current['x'] = -$offset['x'];
        $current['z']--;
    }
    $lines['x'][2] = $current['x'];
    $lines['y'][2] = $offset['y'];
    $lines['z'][2] = $current['z'];

    echo $lines['x'][2].", ".$lines['z'][2].", ".$lines['y'][2]."</br> \n";
    if($i%5 == 0){ //basic formatting decides when a new line must be placed
        $Nl = " \n";
    }else{
        $Nl = " ";
    }
    foreach($points as $value){
        if(minAngle($lines, $value)){
            $colour = "255";
            echo "white </br>\n";
            break 1;
        }else{
            $colour = "000";
        }
    }
    $write = "$Nl$colour $colour $colour"; //the line that is to be outputted
    fwrite($fh, $write); //write the pixel to the file.

}
fclose($fh);
?>