var driverInterval=50;var turnRate=360/4000;var acceleRate=0.00005;var torpDV=0.15;var torpLifetime=5000;var maxTorps=5;var eSpeedLimit=0.08;var eFireDistance=200;var explosionTime=200;var endGameTime=7000;var nExplosions=6;var explosionDV=0.05;var yshipSize=eshipSize=32;var ytorpSize=etorpSize=2;var yexplosionSize=eexplosionSize=64;var nExplosionImages=5;var spaceElement=document.getElementById('space');var spaceWidth,spaceHeight;var yscoreElement=document.getElementById('yscore');var escoreElement=document.getElementById('escore');var yscore,escore;var objects;var yship,eship;var restartTime;var paused;var infoClosedElement=document.getElementById('infoClosed');var infoOpenElement=document.getElementById('infoOpen');var startElement=document.getElementById('start');var logElement=document.getElementById('log');function Setup()
{InfoOpen();document.onkeydown=KeyHandler;document.onkeyup=KeyHandler;window.onresize=ResizeHandler;ResizeHandler();yscore=0;escore=0;DisplayScores();InitGame();}
function InfoOpen()
{paused=true;infoClosedElement.style.display='none';infoOpenElement.style.display='';}
function InfoClose()
{paused=false;infoOpenElement.style.display='none';startElement.innerHTML=' Resume ';infoClosedElement.style.display='';}
function InitGame()
{objects=[];yship=MakeObject({type:'ship',image:'yship_%.gif',aimage:'yshipa_%.gif',size:yshipSize,x:spaceWidth/4,y:spaceHeight-spaceHeight/4,angle:0,dx:0,dy:0,expires:0,torpImage:'ytorp2.gif',torpSize:ytorpSize,explosionImage:'yexplosion1.gif',explosionSize:yexplosionSize,nTorps:0,left:false,right:false,thrust:false});eship=MakeObject({type:'ship',image:'eship_%.gif',aimage:'eshipa_%.gif',size:eshipSize,x:spaceWidth-spaceWidth/4,y:spaceHeight/4,angle:180,dx:0,dy:0,expires:0,torpImage:'etorp2.gif',torpSize:etorpSize,explosionImage:'eexplosion1.gif',explosionSize:eexplosionSize,nTorps:0,left:false,right:false,thrust:false});restartTime=0;Driver();}
var prevTime=null;function Driver()
{var time=ClockMsecs();if(!paused)
{if(restartTime!=0&&time>=restartTime)
{while(objects.length>0)
RemoveObject(objects[0]);InitGame();return;}
if(prevTime)
{var interval=time-prevTime;CheckCollisions(time);CheckExpirations(time);if(eship)
EnemyStrategy();if(yship)
Action(yship,interval);if(eship)
Action(eship,interval);for(var i=0;i<objects.length;++i)
Move(objects[i],interval);}}
Display();prevTime=time;setTimeout(Driver,driverInterval);}
function CheckCollisions(time)
{if(yship&&eship&&Collision(yship,eship))
{Explode(time,yship);++escore;Explode(time,eship);++yscore;DisplayScores();}
else
{if(yship)
{for(var i=0;i<objects.length;++i)
{var o=objects[i];if(o.type=='torp'&&Collision(yship,o))
{RemoveObject(o);--o.ship.nTorps;Explode(time,yship);++escore;DisplayScores();break;}}}
if(eship)
{for(var i=0;i<objects.length;++i)
{var o=objects[i];if(o.type=='torp'&&Collision(eship,o))
{RemoveObject(o);--o.ship.nTorps;Explode(time,eship);++yscore;DisplayScores();break;}}}}}
function Collision(o1,o2)
{if(o1.x+o1.size/2.5<o2.x-o2.size/2.5)
return false;if(o1.x-o1.size/2.5>o2.x+o2.size/2.5)
return false;if(o1.y+o1.size/2.5<o2.y-o2.size/2.5)
return false;if(o1.y-o1.size/2.5>o2.y+o2.size/2.5)
return false;return true;}
function Explode(time,ship)
{for(i=0;i<nExplosions;++i)
{MakeObject({type:'explosion',image:ship.explosionImage,size:ship.explosionSize,x:ship.x+Math.random()*ship.size-ship.size/2,y:ship.y+Math.random()*ship.size-ship.size/2,dx:ship.dx+Math.random()*explosionDV*2-explosionDV,dy:ship.dy+Math.random()*explosionDV*2-explosionDV,expires:time+explosionTime+Math.random()*explosionTime/5-explosionTime/10,expireProc:ExplosionExpire});}
RemoveObject(ship);restartTime=time+endGameTime;}
function CheckExpirations(time)
{for(var i=objects.length-1;i>=0;--i)
{var o=objects[i];if(o.expires!=0&&time>=o.expires)
{RemoveObject(o);if(o.expireProc)
o.expireProc(time,o);}}}
function EnemyStrategy()
{if(!yship)
{eship.left=eship.right=eship.thrust=false;return;}
var dx=eship.x-yship.x;var dy=eship.y-yship.y;var desiredAngle=Mod(RadToDeg(Math.atan2(-dx,dy)),360);var deltaAngle=desiredAngle-eship.angle;if(deltaAngle>180)deltaAngle-=360;else if(deltaAngle<-180)deltaAngle+=360;if(deltaAngle<-10||(eship.left&&deltaAngle<5))
{eship.left=true;eship.right=false;eship.thrust=false;}
else if(deltaAngle>10||(eship.right&&deltaAngle>-5))
{eship.right=true;eship.left=false;eship.thrust=false;}
else
{eship.left=eship.right=false;var v=Math.sqrt(eship.dx*eship.dx+eship.dy*eship.dy);var r=DegToRad(eship.angle);var newDX=eship.dx+acceleRate*driverInterval*Math.sin(r);var newDY=eship.dy-acceleRate*driverInterval*Math.cos(r);var newV=Math.sqrt(newDX*newDX+newDY*newDY);if(eship.thrust)
{if(newV>=eSpeedLimit||Math.random()<0.15)
eship.thrust=false;}
else
{if((newV<eSpeedLimit||newV<v)&&Math.random()<0.10)
eship.thrust=true;}
var distance=Math.sqrt(dx*dx+dy+dy);if(distance<eFireDistance&&Math.random()<0.20)
Fire(eship);}}
function Action(ship,interval)
{if(ship.thrust)
{var r=DegToRad(ship.angle);ship.dx+=acceleRate*interval*Math.sin(r);ship.dy-=acceleRate*interval*Math.cos(r);}
if(ship.left&&!ship.right)
ship.angle=Mod(ship.angle-turnRate*interval,360);else if(ship.right&&!ship.left)
ship.angle=Mod(ship.angle+turnRate*interval,360);}
function Move(object,interval)
{object.x=Mod(object.x+object.dx*interval,spaceWidth);object.y=Mod(object.y+object.dy*interval,spaceHeight);}
function Display()
{for(var i=0;i<objects.length;++i)
{var o=objects[i];var e=o.element;e.style.left=Math.round(o.x-o.size/2)+'px';e.style.top=Math.round(o.y-o.size/2)+'px';var image=o.thrust?o.aimage:o.image;var percent=image.indexOf('%');if(percent!=-1)
image=image.substring(0,percent)+ZeroPad(Math.round(o.angle),3)+image.substring(percent+1);spacewar_SetImage(e,'images/'+image);}}
function DisplayScores()
{DisplayScore(yscoreElement,yscore,'y');DisplayScore(escoreElement,escore,'e');}
function DisplayScore(element,score,letter)
{var str=score+'';var html='';for(var i=0;i<str.length;++i)
html+='<img src="images/'+letter+'digit'+str.charAt(i)+'.gif">';element.innerHTML=html;}
var kcSpace=32;var kcLeft=37;var kcRight=39;var kcUp=38;var kcDown=40;var kcEscape=27;function KeyHandler(e)
{if(paused||!yship)
return;if(!e)
e=window.event;var t=e.type;var kc=e.keyCode||e.which;if(t=='keydown')
{switch(kc)
{case kcSpace:Fire(yship);break;case kcLeft:yship.left=true;break;case kcRight:yship.right=true;break;case kcUp:yship.thrust=true;break;}}
else if(t=='keyup')
{switch(kc)
{case kcLeft:yship.left=false;break;case kcRight:yship.right=false;break;case kcUp:yship.thrust=false;break;}}}
function Fire(ship)
{if(ship.nTorps<maxTorps)
{++ship.nTorps;var r=DegToRad(ship.angle);var s=Math.sin(r);var c=Math.cos(r);MakeObject({type:'torp',image:ship.torpImage,size:ship.torpSize,x:ship.x+ship.size/1.3*s,y:ship.y-ship.size/1.3*c,dx:ship.dx+torpDV*s,dy:ship.dy-torpDV*c,expires:ClockMsecs()+torpLifetime,expireProc:TorpExpire,ship:ship});}}
function TorpExpire(time,torp)
{--torp.ship.nTorps;}
function ExplosionExpire(time,explosion)
{var image=explosion.image;var digitIndex=image.search(/[0-9]/);var periodIndex=image.indexOf('.');var explosionNumber=image.substring(digitIndex,periodIndex);var newExplosionNumber=(+explosionNumber)+1;if(newExplosionNumber<=nExplosionImages)
{var newImage=image.substring(0,digitIndex)+newExplosionNumber+image.substring(periodIndex);MakeObject({type:'explosion',image:newImage,size:explosion.size,x:explosion.x,y:explosion.y,dx:explosion.dx,dy:explosion.dy,expires:time+explosionTime,expireProc:ExplosionExpire});}}
function MakeObject(props)
{props.element=spacewar_MakeSprite(spaceElement);props.element.style.position='absolute';objects.push(props);return props;}
function RemoveObject(object)
{spacewar_RemoveSprite(object.element);for(var i=0;i<objects.length;++i)
if(objects[i]==object)
{objects.splice(i,1);break;}
if(object==yship)
yship=null;else if(object==eship)
eship=null;}
function ResizeHandler(e)
{spaceWidth=spaceElement.clientWidth;spaceHeight=spaceElement.clientHeight;var spaceSize=Math.min(spaceWidth,spaceHeight);torpLifetime=spaceSize/torpDV*0.8;}
function ClockMsecs()
{var d=new Date();return d.getTime();}
function ZeroPad(n,l)
{var zeros='00000000000000000000';var s=n+'';return zeros.substr(0,l-s.length)+s;}
function DegToRad(a)
{return a*Math.PI/180;}
function RadToDeg(a)
{return a*180/Math.PI;}
function Mod(a,b)
{return(a+b)%b;}
function Log(message)
{logElement.style.display='';logElement.innerHTML+=message+'<br>';logElement.scrollTop=logElement.scrollHeight;}