<SCRIPT type="text/javascript"><!--
/*
This code is copyright by Benjamin Joffe.
You may not reproduce or modify this without
written permission by the origional author.
Email him: CanvasGame@gmail.com for suggestions.
*/


// corrections for opera 9.
function hexadecimal(n) {var r='0123456789ABCDEF';  var i=Math.floor(n/16); return r.charAt(i)+r.charAt(n-i*16); }



var map=document.getElementById("map");
var canvas;
var overlay;
//variables initiated at the bottom of the code...

var pi=Math.PI;

var total=0;

Number.prototype.range=function(){
	return (this+2*pi)%(2*pi);
}
Number.prototype.roundC=function(){
	return Math.round(this*100)/100;
}

var total=0;

var samples=200;


var arena=[];
arena[0]=[1,1,1,1,1,1,1,1,1,1]
arena[1]=[1,0,0,0,0,0,0,0,0,1]
arena[2]=[1,0,0,1,0,1,1,1,0,1]
arena[3]=[1,0,1,0,0,0,0,1,0,1]
arena[4]=[1,0,0,0,0,1,0,1,0,1]
arena[5]=[1,0,1,1,0,0,0,0,0,1]
arena[6]=[1,0,0,1,0,1,1,1,0,1]
arena[7]=[1,1,0,1,0,0,0,1,0,1]
arena[8]=[1,0,0,1,0,1,0,0,0,1]
arena[9]=[1,1,1,1,1,1,1,1,1,1]


var playerPos=[4,4]; // x,y (from top left)
var playerDir=0.4; // theta, facing right=0=2pi
var playerPosZ=1;
var key=[0,0,0,0,0]; // left, right, up, down

var playerVelY=0;


var face=[];

function wallDistance(theta){

	var data=[];
	face=[];

	var x = playerPos[0], y = playerPos[1];
	var deltaX, deltaY;
	var distX, distY;
	var stepX, stepY;
	var mapX, mapY
	
	var atX=Math.floor(x), atY=Math.floor(y);

	var thisRow=-1;
	var thisSide=-1;

	var lastHeight=0;

	for (var i=0; i<samples; i++) {
		theta+=pi/(3*samples)+2*pi;
		theta%=2*pi;

		mapX = atX, mapY = atY;

		deltaX=1/Math.cos(theta);
		deltaY=1/Math.sin(theta);

		if (deltaX>0) {
			stepX = 1;
			distX = (mapX + 1 - x) * deltaX;
		}
		else {
			stepX = -1;
			distX = (x - mapX) * (deltaX*=-1);		
		}
		if (deltaY>0) {
			stepY = 1;
			distY = (mapY + 1 - y) * deltaY;
		}
		else {
			stepY = -1;
			distY = (y - mapY) * (deltaY*=-1);
		}
		

		for (var j=0; j<10; j++) {
			if (distX < distY) {
				mapX += stepX;
				if (arena[mapX][mapY]) {
					if (thisRow!=mapX || thisSide!=0) {
						if (i>0) {
							data.push(i);
							data.push(lastHeight);
						}
						data.push(i);
						data.push(distX);
						thisSide=0;
						thisRow=mapX;
						face.push(1+stepX);
					}
					lastHeight=distX;
					break;
				}
				distX += deltaX;
			}
			else {
				mapY += stepY;
				if (arena[mapX][mapY]) {
					if (thisRow!=mapY || thisSide!=1) {
						if (i>0) {
							data.push(i);
							data.push(lastHeight);
						}	
						data.push(i);
						data.push(distY);
						thisSide=1;
						thisRow=mapY;
						face.push(2+stepY)
					}
					lastHeight=distY;
					break;
				}
				distY += deltaY;
			}
		}
	}
	data.push(i);
	data.push(lastHeight);
	
	return data;
}



function drawCanvas(){

	canvas.clearRect(0,0,400, 300);

	var theta = playerDir-pi/6;

	var wall=wallDistance(theta);

	map.clearRect(0,0,80,80);
	map.fillStyle="#3366CC";
	map.arc(playerPos[0]*8, playerPos[1]*8, 3, 0, 2*pi, true);
	map.fill();
	map.moveTo(8*playerPos[0], 8*playerPos[1]);


	var linGrad;
	
	var tl,tr,bl,br;
	
	var theta1,theta2,fix1,fix2;
	
	for (var i=0; i<wall.length; i+=4) {

		theta1=playerDir-pi/6 + pi*wall[i]/(3*samples);
		theta2=playerDir-pi/6 + pi*wall[i+2]/(3*samples);
		
		fix1 = Math.cos(theta1-playerDir);
		fix2 = Math.cos(theta2-playerDir);

		var h=2-playerPosZ;

		var wallH1=100/(wall[i+1]*fix1);
		var wallH2=100/(wall[i+3]*fix2);

		tl=[wall[i]*2, 150-wallH1*h];
		tr=[wall[i+2]*2, 150-wallH2*h]
		br=[wall[i+2]*2, tr[1]+wallH2*2];
		bl=[wall[i]*2, tl[1]+wallH1*2]

		var shade1=Math.floor(wallH1*2+20); if (shade1>255) shade1=255;
		var shade2=Math.floor(wallH2*2+20); if (shade2>255) shade2=255;

// corrections for opera 9. Replaced rgb(r,g,b) by #RRGGBB
		linGrad = canvas.createLinearGradient(tl[0],0,tr[0],0);
		linGrad.addColorStop(0, '#'+hexadecimal(face[i/4]%2==0 ? shade1 : 0)+hexadecimal(face[i/4]==1 ? shade1 : 0)+hexadecimal(face[i/4]==2 ? 0 : shade1));
		linGrad.addColorStop(1, '#'+hexadecimal(face[i/4]%2==0 ? shade2 : 0)+hexadecimal(face[i/4]==1 ? shade2 : 0)+hexadecimal(face[i/4]==2 ? 0 : shade2));

		canvas.beginPath();
		canvas.moveTo(tl[0], tl[1]);
		canvas.lineTo(tr[0], tr[1]);
		canvas.lineTo(br[0], br[1]);
		canvas.lineTo(bl[0], bl[1]);
		canvas.fillStyle = linGrad;
		canvas.fill();

	
		map.lineTo(playerPos[0]*8+Math.cos(theta1)*(wall[i+1])*8, playerPos[1]*8+Math.sin(theta1)*(wall[i+1])*8);
		map.lineTo(playerPos[0]*8+Math.cos(theta2)*(wall[i+3])*8, playerPos[1]*8+Math.sin(theta2)*(wall[i+3])*8);

		
	}

	map.fillStyle="#FF0000"
	map.fill();
	
}

function nearWall(x,y){
	var xx,yy;
	if (isNaN(x)) x=playerPos[0];
	if (isNaN(y)) y=playerPos[1];
	for (var i=-0.1; i<=0.1; i+=0.2) {
		xx=Math.floor(x+i)
		for (var j=-0.1; j<=0.1; j+=0.2) {
			yy=Math.floor(y+j);
			if (arena[xx][yy]) return true;
		}
	}
	return false;
}

function wobbleGun(){
	var mag=playerVelY;
	overlay.style.backgroundPosition=(10+Math.cos(total/6.23)*mag*90)+"px "+(10+Math.cos(total/5)*mag*90)+"px";
}


var jumpCycle=0;


function update(){

	total++;

	var change=false;

	if (jumpCycle) {
		jumpCycle--;
		change=true;
		playerPosZ = 1 + jumpCycle*(20-jumpCycle)/110;
	}
	else if (key[4]) jumpCycle=20;
	
	if (key[0]) {
		if (!key[1]) {
			playerDir-=0.07; //left
			change=true;
		}
	}
	else if (key[1]) {
		playerDir+=0.07; //right
		change=true;
	}

	if (change) {
		playerDir+=2*pi;
		playerDir%=2*pi;
		document.getElementById("sky").style.backgroundPosition=Math.floor(-playerDir/(2*pi)*2400)+"px 0";
	}

	if (key[2] && !key[3]) {
		if (playerVelY<0.1) playerVelY += 0.02;
	}
	else if (key[3] && !key[2]) {
		if (playerVelY>-0.1) playerVelY -= 0.02;
	}
	else {
		if (playerVelY<-0.02) playerVelY += 0.015;
		else if (playerVelY>0.02) playerVelY -= 0.015;
		else playerVelY=0;
	}
	
	
	if (playerVelY!=0) {

		var oldX=playerPos[0];;
		var oldY=playerPos[1];		
		var newX=oldX+Math.cos(playerDir)*playerVelY;
		var newY=oldY+Math.sin(playerDir)*playerVelY;

		if (!nearWall(newX, oldY)) {
			playerPos[0]=newX;
			oldX=newX;
			change=true;
		}
		if (!nearWall(oldX, newY)) {
			playerPos[1]=newY;
			change=true;
		}

	}
	
	if (playerVelY) wobbleGun();
	if (change) drawCanvas();
}


document.onkeydown=function(e){
	 switch (e.keyCode){
		case 65: case 37: key[0]=1; break; // left
		case 87: case 38: key[2]=1; break; // up
		case 68: case 39: key[1]=1; break; // right
		case 83: case 40: key[3]=1; break;// down
		case 32: key[4]=1; break; // space bar;
	}
}
document.onkeyup=function(e){
	 switch (e.keyCode){
		case 65: case 37: key[0]=0; break; // left
		case 87: case 38: key[2]=0; break; // up
		case 68: case 39: key[1]=0; break; // right
		case 83: case 40: key[3]=0; break;// down
		case 32: key[4]=0; break; // space bar;
	}
}


function initUnderMap(){
	var underMap=document.getElementById("underMap").getContext("2d");
	underMap.fillStyle="#FFF";
	underMap.fillRect(0,0, 200, 200);
	underMap.fillStyle="#444";
	for (var i=0; i<arena.length; i++) {
		for (var j=0; j<arena[i].length; j++) {
			if (arena[i][j]) underMap.fillRect(i*8, j*8, 8, 8);
		}	
	}
}

if (!map.getContext) {
	alert("BROWSER INCOMPATABILITY\n\nTo use this feature you need a browser that supports the\n<canvas> HTML element with JavaScript enabled such as\nFirefox 1.5 or Safari 1.3.");
}
else {
	map=map.getContext("2d");
	canvas=document.getElementById("canvas").getContext("2d");
	overlay=document.getElementById("overlay");
	document.getElementById("sky").style.backgroundPosition=Math.floor(-playerDir/(2*pi)*2400)+"px 0";
	drawCanvas();
	initUnderMap();
	setInterval(update, 35);
}




//--></SCRIPT>