1，样例说明
（1）在没有鼠标介入的情况下，这些球就像有磁性一样拼成“Google”字样。
（2）在鼠标移动到其中后，小球像是受到了排斥，向画布的四周扩散，然后不规则地反弹回来。
原文出自：www.hangge.com 转载请保留原文链接：http://www.hangge.com/blog/cache/detail_1059.html
2.源码：
<!DOCTYPE HTML>
<html> <head> <style> body { margin: 0px; padding: 0px; } canvas { cursor: pointer; border: 1px solid black; margin:20px 20px 20px 20px; } </style> </head> <body> <canvas id="myCanvas" width="578" height="200"></canvas> <script> window.requestAnimFrame = (function(callback) { return window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame || function(callback) { window.setTimeout(callback, 1000 / 60); }; })(); function initBalls() { balls = []; var blue = '#3A5BCD'; var red = '#EF2B36'; var yellow = '#FFC636'; var green = '#02A817'; // G balls.push(new Ball(173, 63, 0, 0, blue)); balls.push(new Ball(158, 53, 0, 0, blue)); balls.push(new Ball(143, 52, 0, 0, blue)); balls.push(new Ball(130, 53, 0, 0, blue)); balls.push(new Ball(117, 58, 0, 0, blue)); balls.push(new Ball(110, 70, 0, 0, blue)); balls.push(new Ball(102, 82, 0, 0, blue)); balls.push(new Ball(104, 96, 0, 0, blue)); balls.push(new Ball(105, 107, 0, 0, blue)); balls.push(new Ball(110, 120, 0, 0, blue)); balls.push(new Ball(124, 130, 0, 0, blue)); balls.push(new Ball(139, 136, 0, 0, blue)); balls.push(new Ball(152, 136, 0, 0, blue)); balls.push(new Ball(166, 136, 0, 0, blue)); balls.push(new Ball(174, 127, 0, 0, blue)); balls.push(new Ball(179, 110, 0, 0, blue)); balls.push(new Ball(166, 109, 0, 0, blue)); balls.push(new Ball(156, 110, 0, 0, blue)); // O balls.push(new Ball(210, 81, 0, 0, red)); balls.push(new Ball(197, 91, 0, 0, red)); balls.push(new Ball(196, 103, 0, 0, red)); balls.push(new Ball(200, 116, 0, 0, red)); balls.push(new Ball(209, 127, 0, 0, red)); balls.push(new Ball(223, 130, 0, 0, red)); balls.push(new Ball(237, 127, 0, 0, red)); balls.push(new Ball(244, 114, 0, 0, red)); balls.push(new Ball(242, 98, 0, 0, red)); balls.push(new Ball(237, 86, 0, 0, red)); balls.push(new Ball(225, 81, 0, 0, red)); // O var oOffset = 67; balls.push(new Ball(oOffset + 210, 81, 0, 0, yellow)); balls.push(new Ball(oOffset + 197, 91, 0, 0, yellow)); balls.push(new Ball(oOffset + 196, 103, 0, 0, yellow)); balls.push(new Ball(oOffset + 200, 116, 0, 0, yellow)); balls.push(new Ball(oOffset + 209, 127, 0, 0, yellow)); balls.push(new Ball(oOffset + 223, 130, 0, 0, yellow)); balls.push(new Ball(oOffset + 237, 127, 0, 0, yellow)); balls.push(new Ball(oOffset + 244, 114, 0, 0, yellow)); balls.push(new Ball(oOffset + 242, 98, 0, 0, yellow)); balls.push(new Ball(oOffset + 237, 86, 0, 0, yellow)); balls.push(new Ball(oOffset + 225, 81, 0, 0, yellow)); // G balls.push(new Ball(370, 80, 0, 0, blue)); balls.push(new Ball(358, 79, 0, 0, blue)); balls.push(new Ball(346, 79, 0, 0, blue)); balls.push(new Ball(335, 84, 0, 0, blue)); balls.push(new Ball(330, 98, 0, 0, blue)); balls.push(new Ball(334, 111, 0, 0, blue)); balls.push(new Ball(348, 116, 0, 0, blue)); balls.push(new Ball(362, 109, 0, 0, blue)); balls.push(new Ball(362, 94, 0, 0, blue)); balls.push(new Ball(355, 128, 0, 0, blue)); balls.push(new Ball(340, 135, 0, 0, blue)); balls.push(new Ball(327, 142, 0, 0, blue)); balls.push(new Ball(325, 155, 0, 0, blue)); balls.push(new Ball(339, 165, 0, 0, blue)); balls.push(new Ball(352, 166, 0, 0, blue)); balls.push(new Ball(367, 161, 0, 0, blue)); balls.push(new Ball(371, 149, 0, 0, blue)); balls.push(new Ball(366, 137, 0, 0, blue)); // L balls.push(new Ball(394, 49, 0, 0, green)); balls.push(new Ball(381, 50, 0, 0, green)); balls.push(new Ball(391, 61, 0, 0, green)); balls.push(new Ball(390, 73, 0, 0, green)); balls.push(new Ball(392, 89, 0, 0, green)); balls.push(new Ball(390, 105, 0, 0, green)); balls.push(new Ball(390, 118, 0, 0, green)); balls.push(new Ball(388, 128, 0, 0, green)); balls.push(new Ball(400, 128, 0, 0, green)); // E balls.push(new Ball(426, 101, 0, 0, red)); balls.push(new Ball(436, 98, 0, 0, red)); balls.push(new Ball(451, 95, 0, 0, red)); balls.push(new Ball(449, 83, 0, 0, red)); balls.push(new Ball(443, 78, 0, 0, red)); balls.push(new Ball(430, 77, 0, 0, red)); balls.push(new Ball(418, 82, 0, 0, red)); balls.push(new Ball(414, 93, 0, 0, red)); balls.push(new Ball(412, 108, 0, 0, red)); balls.push(new Ball(420, 120, 0, 0, red)); balls.push(new Ball(430, 127, 0, 0, red)); balls.push(new Ball(442, 130, 0, 0, red)); balls.push(new Ball(450, 125, 0, 0, red)); return balls; } function getMousePos(canvas, evt) { // get canvas position var obj = canvas; var top = 0; var left = 0; while(obj.tagName != 'BODY') { top += obj.offsetTop; left += obj.offsetLeft; obj = obj.offsetParent; } // return relative mouse position var mouseX = evt.clientX - left + window.pageXOffset; var mouseY = evt.clientY - top + window.pageYOffset; return { x: mouseX, y: mouseY }; } function updateBalls(canvas, balls, timeDiff, mousePos) { var context = canvas.getContext('2d'); var collisionDamper = 0.3; var floorFriction = 0.0005 * timeDiff; var mouseForceMultiplier = 1 * timeDiff; var restoreForce = 0.002 * timeDiff; for(var n = 0; n < balls.length; n++) { var ball = balls[n]; // set ball position based on velocity ball.y += ball.vy; ball.x += ball.vx; // restore forces if(ball.x > ball.origX) { ball.vx -= restoreForce; } else { ball.vx += restoreForce; } if(ball.y > ball.origY) { ball.vy -= restoreForce; } else { ball.vy += restoreForce; } // mouse forces var mouseX = mousePos.x; var mouseY = mousePos.y; var distX = ball.x - mouseX; var distY = ball.y - mouseY; var radius = Math.sqrt(Math.pow(distX, 2) + Math.pow(distY, 2)); var totalDist = Math.abs(distX) + Math.abs(distY); var forceX = (Math.abs(distX) / totalDist) * (1 / radius) * mouseForceMultiplier; var forceY = (Math.abs(distY) / totalDist) * (1 / radius) * mouseForceMultiplier; if(distX > 0) {// mouse is left of ball ball.vx += forceX; } else { ball.vx -= forceX; } if(distY > 0) {// mouse is on top of ball ball.vy += forceY; } else { ball.vy -= forceY; } // floor friction if(ball.vx > 0) { ball.vx -= floorFriction; } else if(ball.vx < 0) { ball.vx += floorFriction; } if(ball.vy > 0) { ball.vy -= floorFriction; } else if(ball.vy < 0) { ball.vy += floorFriction; } // floor condition if(ball.y > (canvas.height - ball.radius)) { ball.y = canvas.height - ball.radius - 2; ball.vy *= -1; ball.vy *= (1 - collisionDamper); } // ceiling condition if(ball.y < (ball.radius)) { ball.y = ball.radius + 2; ball.vy *= -1; ball.vy *= (1 - collisionDamper); } // right wall condition if(ball.x > (canvas.width - ball.radius)) { ball.x = canvas.width - ball.radius - 2; ball.vx *= -1; ball.vx *= (1 - collisionDamper); } // left wall condition if(ball.x < (ball.radius)) { ball.x = ball.radius + 2; ball.vx *= -1; ball.vx *= (1 - collisionDamper); } } } function Ball(x, y, vx, vy, color) { this.x = x; this.y = y; this.vx = vx; this.vy = vy; this.color = color; this.origX = x; this.origY = y; this.radius = 10; } function animate(canvas, balls, lastTime, mousePos) { var context = canvas.getContext('2d'); // update var date = new Date(); var time = date.getTime(); var timeDiff = time - lastTime; updateBalls(canvas, balls, timeDiff, mousePos); lastTime = time; // clear context.clearRect(0, 0, canvas.width, canvas.height); // render for(var n = 0; n < balls.length; n++) { var ball = balls[n]; context.beginPath(); context.arc(ball.x, ball.y, ball.radius, 0, 2 * Math.PI, false); context.fillStyle = ball.color; context.fill(); } // request new frame requestAnimFrame(function() { animate(canvas, balls, lastTime, mousePos); }); } var canvas = document.getElementById('myCanvas'); var balls = initBalls(); var date = new Date(); var time = date.getTime(); /* * set mouse position really far away * so the mouse forces are nearly obsolete */ var mousePos = { x: 9999, y: 9999 }; canvas.addEventListener('mousemove', function(evt) { var pos = getMousePos(canvas, evt); mousePos.x = pos.x; mousePos.y = pos.y; }); canvas.addEventListener('mouseout', function(evt) { mousePos.x = 9999; mousePos.y = 9999; }); animate(canvas, balls, time, mousePos); </script> </body></html>