/** JavaScript Object Flying **/

var bt_s='../images/bfly.gif';
var bt_w =28;
var bt_h =20;
var bt_z= 2;
var bt_n= 2;
var bt_time=150;
var bt_step= 12;
var bt_angle= 72;
var bt_aiint= 8;
var bt_sleep=0.2;
var bt=bt_n-1;
var bt_aicount=-1;
var bt_dir=0;
var bt_basex=0;
var bt_basey=0;
function bt_init(){
bt_angle/=180;
var t='<div id=btl style=position:absolute;z-index:'+bt_z+';width:'+bt_w+';height:'+bt_h+'>';
document.write(t);
for(var i=0;i<bt_n;i++){
var t='<img id=bti src='+bt_s.replace(/\#/,String(i+1));
t+=' style=position:absolute;visibility:hidden;width:'+bt_w+';height:'+bt_h+'>';
document.write(t);
}
for(var i=0;i<bt_n;i++){
var t='<img id=bti src='+bt_s.replace(/\#/,String(i+1));
t+=' style=position:absolute;visibility:hidden;width:'+bt_w+';height:'+bt_h+';filter:FlipH()>';
document.write(t);
}
document.write('</div>');
setInterval('bt_main();',bt_time);
}
function bt_main(){
bti[bt].style.visibility='hidden';
if(bt_aicount==-1){
bt_aicount=bt_aiint-1;
var x0=document.body.clientWidth-bt_w;
var y0=(document.body.clientHeight-bt_h)/2;
btl.style.pixelLeft=x0;
btl.style.pixelTop=y0;
}
bt_aicount++;
if(bt_aicount==bt_aiint){
bt_aicount=0;
bt_ai();
bt_basex=btl.style.pixelLeft;
bt_basey=btl.style.pixelTop;
}
if(bt_dir!=256){
var x1=bt_basex+(bt_step*Math.cos(bt_dir)*(bt_aicount+1));
var y1=bt_basey-(bt_step*Math.sin(bt_dir)*(bt_aicount+1));
var x2=document.body.clientWidth-bt_w;
var y2=document.body.clientHeight-bt_h+document.body.scrollTop;
if(x1<0){x1=0;}
if(x1>x2){x1=x2;}
if(y1<document.body.scrollTop){y1=document.body.scrollTop;}
if(y1>y2){y1=y2;}
btl.style.pixelLeft=x1;
btl.style.pixelTop=y1;
}
var t1=0;
if(bt>=bt_n){bt-=bt_n;t1=bt_n;}
bt=bt+1;
if(bt>=bt_n){bt=0;}
if(bt_dir!=256){
if((bt_dir<Math.PI/2)||(Math.PI/2*3<bt_dir)){bt+=bt_n;}
}else{
bt+=t1;
}
bti[bt].style.visibility='visible';
}
function bt_ai(){
var x0=document.body.clientWidth-bt_w;
var y0=document.body.clientHeight-bt_h;
var x1=btl.style.pixelLeft;
var y1=btl.style.pixelTop-document.body.scrollTop;
var x2=x0/2;
var y2=y0/2;
var d1=Math.sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
if(y1-y2<=0){var rad1=Math.acos((x1-x2)/d1);}
else{var rad1=-Math.acos((x1-x2)/d1)+Math.PI*2;}
var rad2=rad1+Math.PI;
if(rad2>=Math.PI*2){rad2-=Math.PI*2;}
var m1=(y1-y2)/(x1-x2);
var m2=(x1-x2)/(y1-y2);
if(x1-x2>=0){x3=x0;}
else{x3=0;}
if(y1-y2>=0){y4=y0;}
else{y4=0;}
y3=m1*(x3-x2)+y2;
x4=m2*(y4-y2)+x2;
var d3=Math.sqrt((x3-x2)*(x3-x2)+(y3-y2)*(y3-y2));
var d4=Math.sqrt((x4-x2)*(x4-x2)+(y4-y2)*(y4-y2));
var d5=d3;
if(d5>d4){d5=d4;}
var r1=d1/d5;
r1*=r1*1.2; //?A‘?–{”\?&#3597;“x
if(r1>1){r1=1;}
var r2=1-r1;
if(bt_dir==256){var rad3=Math.random()*Math.PI*2;}
else{var rad3=bt_dir+r2*(Math.random()-0.5)*Math.PI*2*bt_angle;}
if(rad3>=2*Math.PI){rad3-=2*Math.PI;}
if(rad3<0){rad3+=2*Math.PI;}
var rad4=rad3-rad2;
if(rad4>=2*Math.PI){rad4-=2*Math.PI;}
if(rad4<0){rad4+=2*Math.PI;}
if(rad4>=Math.PI){rad4-=2*Math.PI;}
if(rad4>=0){var rad5=r1*Math.PI*bt_angle;}
else{var rad5=-r1*Math.PI*bt_angle;}
if(Math.abs(rad5)>=Math.abs(rad4)){rad5=rad4;}
rad3-=rad5;
if(Math.random()<bt_sleep){bt_dir=256;}
else{bt_dir=rad3;}
}
bt_init();