set_time_limit(5);
class raycasting{
	var $map;
	var $pov;
	var $ceiling = 64;
	var $direction;
	var $scale = 32;
	var $map_image;
	var $color;
//function that import a map
function create_map($string){
	$string = explode("\n",$string);
	$i = 0;
	$count = count($string);
	while($i<$count){
		$string[$i] = explode(' ', $string[$i]);
		++$i;
	}
	//now, it should created an array hold the map, it is acessed like $array[$x][$y]
	$this->map = $string;
}
 
function iswall($x, $y){
	if($this->map[floor($x/$this->scale)][floor($y/$this->scale)]){
		return true;
	}else{
		return false;
	}
}
function create_pov($x, $y, $z, $a){
	//$x, $y will be where the character at on the 2D map. $a is the viewing angle
	//don't care about $z, for now $z is half of the scale
	//each value have to be interger except $a. it also have to exsit inside the map
	$border = count($this->map)*$this->scale;
	if($x>$border){
		die('outside border');
	}else{
		$x = abs(round($x));
	}
	$border = count($this->map[0])*$this->scale;
	if($y>$border){
		die('outside border');
	}else{
		$y = abs(round($y));
	}
	//$x, $y can't be in a wall
	if($this->iswall($x, $y)){
		die('this is wall');
	}
	if($z>$this->ceiling){
		$z = $this->ceiling;
	}else{
		$z = abs(round($z));
	}
	//angle treated differently
	while($a < 0){
		$a += 360;
	}
	while($a >= 360){
		$a -= 360;
	}
	//test for y increase or decrease
	if (180>$a){
		$this->direction['y'] = -1;
	}elseif(180<$a){
		$this->direction['y'] = 1;
	}
	//test for x increase or decrease
	if (270>$a && 90<$a){
		$this->direction['x'] = -1;
	}elseif(($a>270 or $a<90) or $a == 0){
		$this->direction['x'] = 1;
	}
	//so if it's 90, 270 ,180 or 0 degree, x or y can be 0;
 
	//create the tri_a, the angle for the triangle it creates
	$tri_a = $a;
	while($tri_a >= 90){
		$tri_a -= 90;
	}
	//post everything as an array for pov
	$this->pov = array('x' => $x,
						'y' => $y,
						'z' => $z,
						'a' => $a,
						'tri_a' => $tri_a);
}
 
function create_map_image(){
 
	$size = imagesx($this->map_image);
	//find the angle to draw
	if($this->direction['x'] == 1 && $this->direction['y'] == 1){
		$x = $size/2 + tan(deg2rad($this->pov['tri_a']))*$size/2;
		$y = $size;
	}elseif($this->direction['x'] == -1 && $this->direction['y'] == -1 ){
		$x = $size/2 - tan(deg2rad($this->pov['tri_a']))*$size/2;
		$y = 0;
	}elseif($this->direction['x'] == -1 && $this->direction['y'] == 1){
		$x = 0;
		$y = $size/2 + tan(deg2rad($this->pov['tri_a']))*$size/2;
	}elseif($this->direction['x'] == 1 && $this->direction['y'] == -1 ){
		$x = $size;
		$y = $size/2 - tan(deg2rad($this->pov['tri_a']))*$size/2;
	}elseif($this->direction['x'] == 0 && $this->direction['y'] == -1){
		$x = $size/2;
		$y = 0;
	}elseif($this->direction['x'] == 0 && $this->direction['y'] == 1){
		$x = $size/2;
		$y = $size;
	}elseif($this->direction['x'] == 1 && $this->direction['y'] == 0){
		$x = $size;
		$y = $size/2;
	}elseif($this->direction['x'] == -1 && $this->direction['y'] == 0){
		$x = 0;
		$y = $size/2;
	}
	//draw angle
	imageline($this->map_image, $size/2, $size/2, $x, $y, $this->color[1]);
	//draw map
	//draw grid
	$x= $this->pov['x'];
	$y= $this->pov['y'];
	//find where $x is in one scale grid;
	while($x > $this->scale){
		$x -= $this->scale;
	}
	while($y > $this->scale){
		$y -= $this->scale;
	}
	//plot user
	//color
	$user_color = imagecolorallocate($this->map_image, 0, 255, 255);
	//plot
	imagerectangle($this->map_image, $size/2-3,$size/2-3,$size/2+3,$size/2+3, $user_color);
	//plot grid;
	$grid_y = $size/2 + $this->scale - $y;
	while($grid_y > 0){
		$grid_y -= $this->scale;
		imageline($this->map_image, 0, $grid_y, $size, $grid_y, $this->color[1]);
	}
	$grid_y = $size/2 - $y;
	while($grid_y < $size){
		$grid_y += $this->scale;
		imageline($this->map_image, 0, $grid_y, $size, $grid_y, $this->color[1]);
	}
	$grid_x = $size/2 - $x;
	while($grid_x < $size){
		$grid_x += $this->scale;
		imageline($this->map_image, $grid_x, 0, $grid_x, $size, $this->color[1]);
	}
	$grid_x = $size/2 + $this->scale - $x;
	while($grid_x > 0){
		$grid_x -= $this->scale;
		imageline($this->map_image, $grid_x, 0, $grid_x, $size, $this->color[1]);
	}
	//find which piece the item is on
		$scale_x= floor($this->pov['x']/$this->scale);
		$scale_y= floor($this->pov['y']/$this->scale);
	//color the wall present
	$i = 0;
	$count = count($this->map);
	$count2 = count($this->map[0]);
 
 
	$i = 0;
	while($i < $count){
		$n = 0;
		while($n < $count2){
	if($this->map[$i][$n]){
					$wall_x = $size/2 + ($i-$scale_x)* $this->scale - $y;
					$wall_y = $size/2 + ($n-$scale_y)* $this->scale - $x;
					imagefilledrectangle($this->map_image, $wall_y, $wall_x, $wall_y + $this->scale, $wall_x + $this->scale, $this->color[1]);
	}
			++$n;
		}
		++$i;
	}
}
}
 
$world = new raycasting;
$map = 
"1 1 1 1 1 1 1 1
1 0 0 0 0 0 0 1
1 1 0 1 1 0 0 1
1 1 1 1 1 1 1 1";
$world->create_map($map);
 
$world->map_image = imagecreate(400, 400);
 
 
	$world->color[] = imagecolorallocate($world->map_image, 0, 0, 0);
	$world->color[] = imagecolorallocate($world->map_image, 255, 255, 255);
 
	$world->create_pov(33,33,65,60);
	$world->create_map_image();
 
//include_once('dbug.php');
//new dbug($world->map);
//new dbug($world->pov);
//new dbug($world->direction);
 
header("Content-type: image/gif");
imagegif($world->map_image);
imagedestroy($world->map_image);