/*
        Original:        Stefano Occhetti
        E-mail:                starnuto_di_topo@hotmil.com
        Web Site:        http://www.geocities.com/starnuto_di_topo_2001

*/


var ns = (document.layers)?1:0;

/*
Button:
        this code is to show a "button" to switch
        the fly ON/OFF.
        It is always shown on the frame's
        bottom-right corner.
------------------------------------------------
*/
var imgwidth=40;        // Image width
var imgheight=40;        // Image height

var button = Array();        // to pre-cache images
button[0]=new Image();
button[0].src="Mosca_OFF.gif";
button[1]=new Image();
button[1].src="Mosca_ON.gif";

var text="<table width=10 bgcolor=#ffffff><td><a href='javascript:showhideAnimation()'><center><img name='Button' src='"+button[0].src+"' width='"+imgwidth+"' height='"+imgheight+"' border='0'></center></a></font></td></table>"        // A bit of HTML code to display the button


//Initialize some variables to make the button always to appear on the frame's bottom-right corner
if (ns) {


}else {

}




setInterval('checkLocation()', 10);

/*
end of Button management
------------------------------------------------
*/




/*
Fly:
        this code provides some facilities
        to show a fly moving on the screen.

        The fly does not actually follow the
        mouse, but a "Dot" (not shown!).
------------------------------------------------
*/


(document.layers)?window.captureEvents(Event.MOUSEMOVE):0;
(document.layers)?window.onMouseMove=getMousePosition:document.onmousemove=getMousePosition;


var Dot_Ro=60;        //Dot's distance from the mouse pointer
var Dot_Theta=0;        //Dot's initial angle
var Dot_Speed;        //Dot's absolute Angular speed
var Dot_Direction=1; //Dot's direction (1=clockwise)
var Dot_x=0;        //Dot's original position
var Dot_y=0;

var alpha;        //Angle from the fly to the mouse
var mult;        //Ausiliary variable to define the angle

var picX = 20;        //Fly's coords.
var picY = 100;
var mouseX = 0;        //Mouse coords.
var mouseY = 0;
var step = 10;        //Pixels
var speed = 100;//u-seconds
var ran_unrounded=Math.random()*800;
var ran_unrounded_y=Math.random()*50;


// Dir specifies the right picture;
// img pre-caches images.
var dir = Array();
dir[-4]="Mosca_3.gif";
dir[-1]="Mosca_6.gif";
dir[-2]="Mosca_5.gif";
dir[-3]="Mosca_4.gif";
dir[3]="Mosca_8.gif";
dir[4]="Mosca_7.gif";
dir[1]="Mosca_2.gif";
dir[2]="Mosca_1.gif";
dir[0]="";

var img = Array();
for (var i=-4; i<5; i++){
        img[i]=new Image();
        img[i].src=""+dir[i];
}

// Some HTML code to show the fly.
if (ns) {
        document.write("<LAYER NAME='FlyDiv' LEFT=0 TOP=0><img src="+img[1].src+" name='pic'></LAYER>");
}else {
        document.write("<div id='FlyDiv' style='position:absolute'>");
        document.write("<img name='pic' src=" + img[1].src + "></div>");
}

// Shows the proper image for the fly.
function display(direction) { //direction must be from -4 to 4, but not 0.
        if (ns) {
                document.pic.src = img[direction].src;
        }else{
                pic.src = img[direction].src;
        }
}


function getMousePosition(e) {
        mouseY=Math.floor(ran_unrounded_y);
        mouseX=Math.floor(ran_unrounded);
}

//Calculate new position
function calcNewPos() {
        /*
                All this calculations make the Dot
                to come near the mouse-pointer,
                and the fly to follow the dot.
        */
        var dist=Math.sqrt(Math.pow(mouseY-picY,2) + Math.pow(mouseX-picX,2));
        Dot_Speed=Math.PI/15;
        Dot_Theta+=Dot_Direction*Dot_Speed;
        Dot_x=mouseX+Dot_Ro*Math.cos(Dot_Theta);
        Dot_y=mouseY+Dot_Ro*Math.sin(Dot_Theta);
        var arg = (Dot_y-picY) / (Dot_x-picX);
        mult = (Dot_x - picX < 0)? mult = -1:1;
        alpha = Math.atan(arg);
        var dx = mult * step * Math.cos(alpha);
        var dy = mult * step * Math.sin(alpha);
        picX += dx;
        picY += dy;
}

//Shows or hides the fly when the "button" is pressed
function showhideAnimation() {
        if (ns) {
                document.layers['FlyDiv'].visibility=document.layers['FlyDiv'].visibility=="hide"?"show":"hide";
                document.Button.src = document.layers['FlyDiv'].visibility=="hide"?button[1].src:button[0].src;
        }else {
                FlyDiv.style.visibility=="hidden"?FlyDiv.style.visibility = "visible":FlyDiv.style.visibility = "hidden";
                Button.src = FlyDiv.style.visibility=="hidden"?button[1].src:button[0].src;
        }
}


// Moves the fly around the screen
function moveFly() {
        // moves the fly in a new position...
        calcNewPos();
        if (ns) {
                document.layers['FlyDiv'].left = picX;
                document.layers['FlyDiv'].top = picY;
        }else{
                FlyDiv.style.left = picX - pic.width / 2;
                FlyDiv.style.top = picY - pic.height / 2;
        }

        // ... and changes the image.
        alpha=-180*alpha/Math.PI;
        alpha+=22.5;
        var OK=0;
        for(var i=0; (i<4)&& !OK; i++){
                if (alpha<-Math.PI+45*i){
                        display(mult*(i+1));
                        OK=1;
                }
        }
}

// Changes Dot's turning direction
function ChangeDotDirection() {
        Dot_Direction=-Dot_Direction;
        Dot_Theta+=Math.PI;
}

//Go!
setInterval('moveFly()', speed);
setInterval('ChangeDotDirection()', speed*50);

/*
The end.
------------------------------------------------
*/