2、跟随鼠标的弹性小球

2、跟随鼠标的弹性小球

<!--将以下代码加入HTML<Body></Body>之间-->

 

<DIV id=dot0

style="HEIGHT: 11px; POSITION: absolute; VISIBILITY: hidden; WIDTH: 11px"><IMG

height=11 src="image/bullet2.gif" width=11> </DIV>

<DIV id=dot1 style="HEIGHT: 11px; POSITION: absolute; WIDTH: 11px"><IMG

height=11 src="image/bullet2.gif" width=11> </DIV>

<DIV id=dot2 style="HEIGHT: 11px; POSITION: absolute; WIDTH: 11px"><IMG

height=11 src="image/bullet2.gif" width=11> </DIV>

<DIV id=dot3 style="HEIGHT: 11px; POSITION: absolute; WIDTH: 11px"><IMG

height=11 src="image/bullet2.gif" width=11> </DIV>

<DIV id=dot4 style="HEIGHT: 11px; POSITION: absolute; WIDTH: 11px"><IMG

height=11 src="image/bullet2.gif" width=11> </DIV>

<DIV id=dot5 style="HEIGHT: 11px; POSITION: absolute; WIDTH: 11px"><IMG

height=11 src="image/bullet2.gif" width=11> </DIV>

<DIV id=dot6 style="HEIGHT: 11px; POSITION: absolute; WIDTH: 11px"><IMG

height=11 src="image/bullet2.gif" width=11> </DIV>

<SCRIPT language=JavaScript>

var nDots = 7;

var Xpos = 0;

var Ypos = 0;

var DELTAT = .01;

var SEGLEN = 10;

var SPRINGK = 10;

var MASS = 1;

var XGRAVITY = 0;

var YGRAVITY = 50;

var RESISTANCE = 10;

var STOPVEL = 0.1;

var STOPACC = 0.1;

var DOTSIZE = 11;

var BOUNCE = 0.75;

var isNetscape = navigator.appName=="Netscape";

var followmouse = true;

var dots = new Array();

init();

function init()

{

    var i = 0;

    for (i = 0; i < nDots; i++) {

        dots[i] = new dot(i);

    }

 

    if (!isNetscape) {

    }

    for (i = 0; i < nDots; i++) {

        dots[i].obj.left = dots[i].X;

        dots[i].obj.top = dots[i].Y;

    }

    if (isNetscape) {

        startanimate();

    } else {

        setTimeout("startanimate()", 1000);

    }

}

function dot(i)

{

    this.X = Xpos;

    this.Y = Ypos;

    this.dx = 0;

    this.dy = 0;

    if (isNetscape) {

        this.obj = eval("document.dot" + i);

    } else {

        this.obj = eval("dot" + i + ".style");

    }

}

function startanimate() {

    setInterval("animate()", 20);

}

function setInitPositions(dots)

{

    var startloc = document.all.tags("LI");

    var i = 0;

    for (i = 0; i < startloc.length && i < (nDots - 1); i++) {

        dots[i+1].X = startloc[i].offsetLeft

            startloc[i].offsetParent.offsetLeft - DOTSIZE;

        dots[i+1].Y = startloc[i].offsetTop +

            startloc[i].offsetParent.offsetTop + 2*DOTSIZE;

    }

    dots[0].X = dots[1].X;

    dots[0].Y = dots[1].Y - SEGLEN;

}

function MoveHandler(e)

{

    Xpos = e.pageX;

    Ypos = e.pageY;

    return true;

}

function MoveHandlerIE() {

    Xpos = window.event.x + document.body.scrollLeft;

    Ypos = window.event.y + document.body.scrollTop;

}

 

if (isNetscape) {

    document.captureEvents(Event.MOUSEMOVE);

    document.onMouseMove = MoveHandler;

} else {

    document.onmousemove = MoveHandlerIE;

}

 

 

function vec(X, Y)

{

    this.X = X;

    this.Y = Y;

}

function springForce(i, j, spring)

{

    var dx = (dots[i].X - dots[j].X);

    var dy = (dots[i].Y - dots[j].Y);

    var len = Math.sqrt(dx*dx + dy*dy);

    if (len > SEGLEN) {

        var springF = SPRINGK * (len - SEGLEN);

        spring.X += (dx / len) * springF;

        spring.Y += (dy / len) * springF;

    }

}

function animate() {

    var start = 0;

    if (followmouse) {

        dots[0].X = Xpos;

        dots[0].Y = Ypos;

        start = 1;

    }

    for (i = start ; i < nDots; i++ ) {

 

        var spring = new vec(0, 0);

        if (i > 0) {

            springForce(i-1, i, spring);

        }

        if (i < (nDots - 1)) {

            springForce(i+1, i, spring);

        }

        var resist = new vec(-dots[i].dx * RESISTANCE,

            -dots[i].dy * RESISTANCE);

        var accel = new vec((spring.X + resist.X)/MASS + XGRAVITY,

            (spring.Y + resist.Y)/ MASS + YGRAVITY);

        dots[i].dx += (DELTAT * accel.X);

        dots[i].dy += (DELTAT * accel.Y);

        if (Math.abs(dots[i].dx) < STOPVEL &&

            Math.abs(dots[i].dy) < STOPVEL &&

            Math.abs(accel.X) < STOPACC &&

            Math.abs(accel.Y) < STOPACC) {

            dots[i].dx = 0;

            dots[i].dy = 0;

        }

        dots[i].X += dots[i].dx;

        dots[i].Y += dots[i].dy;

        var height, width;

        if (isNetscape) {

            height = window.innerHeight + window.pageYOffset;

            width = window.innerWidth + window.pageXOffset;

        } else {

            height = document.body.clientHeight + document.body.scrollTop;

            width = document.body.clientWidth + document.body.scrollLeft;

        }

        if (dots[i].Y >=  height - DOTSIZE - 1) {

            if (dots[i].dy > 0) {

                dots[i].dy = BOUNCE * -dots[i].dy;

            }

            dots[i].Y = height - DOTSIZE - 1;

        }

        if (dots[i].X >= width - DOTSIZE) {

            if (dots[i].dx > 0) {

                dots[i].dx = BOUNCE * -dots[i].dx;

            }

            dots[i].X = width - DOTSIZE - 1;

        }

        if (dots[i].X < 0) {

            if (dots[i].dx < 0) {

                dots[i].dx = BOUNCE * -dots[i].dx;

            }

            dots[i].X = 0;

        }

        dots[i].obj.left = dots[i].X;

        dots[i].obj.top =  dots[i].Y;

    }

}

</SCRIPT>

 

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