js实现暴风雪下雪动画效果代码-html代码-BFW代码库

代码语言：html
所属分类：动画
代码描述：js实现暴风雪下雪动画效果代码
下面为部分代码预览，完整代码请点击下载或在bfwstudio webide中打开
<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">





    <style>
        body {
            background: url(//repo.bfw.wiki/bfwrepo/image/61c93229e7edf.png) no-repeat;
            background-size: cover;
    
        }
    </style>



</head>

<body>



    <script>
     
        
        var snowStorm = function (window, document) {
        
          // --- common properties ---
        
          this.autoStart = true; // Whether the snow should start automatically or not.
          this.excludeMobile = true; // Snow is likely to be bad news for mobile phones' CPUs (and batteries.) Enable at your own risk.
          this.flakesMax = 128; // Limit total amount of snow made (falling + sticking)
          this.flakesMaxActive = 64; // Limit amount of snow falling at once (less = lower CPU use)
          this.animationInterval = 50; // Theoretical "miliseconds per frame" measurement. 20 = fast + smooth, but high CPU use. 50 = more conservative, but slower
          this.useGPU = true; // Enable transform-based hardware acceleration, reduce CPU load.
          this.className = null; // CSS class name for further customization on snow elements
          this.excludeMobile = true; // Snow is likely to be bad news for mobile phones' CPUs (and batteries.) By default, be nice.
          this.flakeBottom = null; // Integer for Y axis snow limit, 0 or null for "full-screen" snow effect
          this.followMouse = false; // Snow movement can respond to the user's mouse
          this.snowColor = '#fff'; // Don't eat (or use?) yellow snow.
          this.snowCharacter = '&bull;'; // &bull; = bullet, &middot; is square on some systems etc.
          this.snowStick = true; // Whether or not snow should "stick" at the bottom. When off, will never collect.
          this.targetElement = null; // element which snow will be appended to (null = document.body) - can be an element ID eg. 'myDiv', or a DOM node reference
          this.useMeltEffect = true; // When recycling fallen snow (or rarely, when falling), have it "melt" and fade out if browser supports it
          this.useTwinkleEffect = false; // Allow snow to randomly "flicker" in and out of view while falling
          this.usePositionFixed = false; // true = snow does not shift vertically when scrolling. May increase CPU load, disabled by default - if enabled, used only where supported
          this.usePixelPosition = false; // Whether to use pixel values for snow top/left vs. percentages. Auto-enabled if body is position:relative or targetElement is specified.
        
          // --- less-used bits ---
        
          this.freezeOnBlur = true; // Only snow when the window is in focus (foreground.) Saves CPU.
          this.flakeLeftOffset = 0; // Left margin/gutter space on edge of container (eg. browser window.) Bump up these values if seeing horizontal scrollbars.
          this.flakeRightOffset = 0; // Right margin/gutter space on edge of container
          this.flakeWidth = 8; // Max pixel width reserved for snow element
          this.flakeHeight = 8; // Max pixel height reserved for snow element
          this.vMaxX = 5; // Maximum X velocity range for snow
          this.vMaxY = 4; // Maximum Y velocity range for snow
          this.zIndex = 0; // CSS stacking order applied to each snowflake
        
          // --- "No user-serviceable parts inside" past this point, yadda yadda ---
        
          var storm = this,
          features,
          // UA sniffing and backCompat rendering mode checks for fixed position, etc.
          isIE = navigator.userAgent.match(/msie/i),
          isIE6 = navigator.userAgent.match(/msie 6/i),
          isMobile = navigator.userAgent.match(/mobile|opera m(ob|in)/i),
          isBackCompatIE = isIE && document.compatMode === 'BackCompat',
          noFixed = isBackCompatIE || isIE6,
          screenX = null,screenX2 = null,screenY = null,scrollY = null,docHeight = null,vRndX = null,vRndY = null,
          windOffset = 1,
          windMultiplier = 2,
          flakeTypes = 6,
          fixedForEverything = false,
          targetElementIsRelative = false,
          opacitySupported = function () {
            try {
              document.createElement('div').style.opacity = '0.5';
            } catch (e) {
              return false;
            }
            return true;
          }(),
          didInit = false,
          docFrag = document.createDocumentFragment();
        
          features = function () {
        
            var getAnimationFrame;
        
            /**
             * hat tip: paul irish
             * http://paulirish.com/2011/requestanimationframe-for-smart-animating/
             * https://gist.github.com/838785
             */
        
            function timeoutShim(callback) {
              window.setTimeout(callback, 1000 / (storm.animationInterval || 20));
            }
        
            var _animationFrame = window.requestAnimationFrame ||
            window.webkitRequestAnimationFrame ||
            window.mozRequestAnimationFrame ||
            window.oRequestAnimationFrame ||
            window.msRequestAnimationFrame ||
            timeoutShim;
        
            // apply to window, avoid "illegal invocation" errors in Chrome
            getAnimationFrame = _animationFrame ? function () {
              return _animationFrame.apply(window, arguments);
            } : null;
        
            var testDiv;
        
            testDiv = document.createElement('div');
        
            function has(prop) {
        
              // test for feature support
              var result = testDiv.style[prop];
              return result !== undefined ? prop : null;
        
            }
        
            // note local scope.
            var localFeatures = {
        
              transform: {
                ie: has('-ms-transform'),
                moz: has('MozTransform'),
                opera: has('OTransform'),
                webkit: has('webkitTransform'),
                w3: has('transform'),
                prop: null // the normalized property value
              },
        
              getAnimationFrame: getAnimationFrame };
        
        
        
            localFeatures.transform.prop =
            localFeatures.transform.w3 ||
            localFeatures.transform.moz ||
            localFeatures.transform.webkit ||
            localFeatures.transform.ie ||
            localFeatures.transform.opera;
        
        
            testDiv = null;
        
            return localFeatures;
        
          }();
        
          this.timer = null;
          this.flakes = [];
          this.disabled = false;
          this.active = false;
          this.meltFrameCount = 20;
          this.meltFrames = [];
        
          this.setXY = function (o, x, y) {
        
            if (!o) {
              return false;
            }
        
            if (storm.usePixelPosition || targetElementIsRelative) {
        
              o.style.left = x - storm.flakeWidth + 'px';
              o.style.top = y - storm.flakeHeight + 'px';
        
            } else if (noFixed) {
        
              o.style.right = 100 - x / screenX * 100 + '%';
              // avoid creating vertical scrollbars
              o.style.top = Math.min(y, docHeight - storm.flakeHeight) + 'px';
        
            } else {
        
              if (!storm.flakeBottom) {
        
                // if not using a fixed bottom coordinate...
                o.style.right = 100 - x / screenX * 100 + '%';
                o.style.bottom = 100 - y / screenY * 100 + '%';
        
              } else {
        
                // absolute top.
                o.style.right = 100 - x / screenX * 100 + '%';
                o.style.top = Math.min(y, docHeight - storm.flakeHeight) + 'px';
        
              }
        
            }
        
          };
        
          this.events = function () {
        
            var old = !window.addEventListener && window.attachEvent,slice = Array.prototype.slice,
            evt = {
              add: old ? 'attachEvent' : 'addEventListener',
              remove: old ? 'detachEvent' : 'removeEventListener' };
        
        
            function getArgs(oArgs) {
              var args = slice.call(oArgs),len = args.length;
              if (old) {
                args[1] = 'on' + args[1]; // prefix
                if (len > 3) {
                  args.pop(); // no capture
                }
              } else if (len === 3) {
                args.push(false);
              }
              return args;
            }
        
            function apply(args, sType) {
              var element = args.shift(),
              method = [evt[sType]];
              if (old) {
                element[method](args[0], args[1]);
              } else {
                element[method].apply(element, args);
              }
            }
        
            function addEvent() {
              apply(getArgs(arguments), 'add');
            }
        
            function removeEvent() {
              apply(getArgs(arguments), 'remove');
            }
        
            return {
              add: addEvent,
              remove: removeEvent };
        
        
          }();
        
          function rnd(n, min) {
            if (isNaN(min)) {
              min = 0;
            }
            return Math.random() * n + min;
          }
        
          function plusMinus(n) {
            return parseInt(rnd(2), 10) === 1 ? n * -1 : n;
          }
        
          this.randomizeWind = function () {
            var i;
            vRndX = plusMinus(rnd(storm.vMaxX, 0.2));
            vRndY = rnd(storm.vMaxY, 0.2);
            if (this.flakes) {
              for (i = 0; i < this.flakes.length; i++) {
                if (this.flakes[i].active) {
                  this.flakes[i].setVelocities();
                }
              }
            }
          };
        
          this.scrollHandler = function () {
            var i;
            // "attach" snowflakes to bottom of window if no absolute bottom value was given
            scrollY = storm.flakeBottom ? 0 : parseInt(window.scrollY || document.documentElement.scrollTop || (noFixed ? document.body.scrollTop : 0), 10);
            if (isNaN(scrollY)) {
              scrollY = 0; // Netscape 6 scroll fix
            }
            if (!fixedForEverything && !storm.flakeBottom && storm.flakes) {
              for (i = 0; i < storm.flakes.length; i++) {
                if (storm.flakes[i].active === 0) {
                  storm.flakes[i].stick();
                }
              }
            }
          };
        
          this.resizeHandler = function () {
            if (window.innerWidth || window.innerHeight) {
              screenX = window.innerWidth - 16 - storm.flakeRightOffset;
              screenY = storm.flakeBottom || window.innerHeight;
            } else {
              screenX = (document.documentElement.clientWidth || document.body.clientWidth || document.body.scrollWidth) - (!isIE ? 8 : 0) - storm.flakeRightOffset;
              screenY = storm.flakeBottom || document.documentElement.clientHeight || document.body.clientHeight || document.body.scrollHeight;
            }
            docHeight = document.body.offsetHeight;
            screenX2 = parseInt(screenX / 2, 10);
          };
        
          this.resizeHandlerAlt = function () {
            screenX = storm.targetElement.offsetWidth - storm.flakeRightOffset;
            screenY = storm.flakeBottom || storm.targetElement.offsetHeight;
            screenX2 = parseInt(screenX / 2, 10);
            docHeight = document.body.offsetHeight;
          };
        
          this.freeze = function () {
            // pause animation
            if (!storm.disabled) {
              storm.disabled = 1;
            } else {
              return false;
            }
            storm.timer = null;
          };
        
          this.resume = function () {
            if (storm.disabled) {
              storm.disabled = 0;
            } else {
              return false;
            }
            storm.timerInit();
          };
        
          this.toggleSnow = function () {
            if (!storm.flakes.length) {
              // first run
              storm.start();
            } else {
              storm.active = !storm.active;
              if (storm.active) {
                storm.show();
                storm.resume();
              } else {
                storm.stop();
                storm.freeze();
              }
            }
          };
        
          this.stop = function () {
            var i;
            this.freeze();
            for (i = 0; i < this.flakes.length; i++) {
              this.flakes[i].o.style.display = 'none';
            }
            storm.events.remove(window, 'scroll', storm.scrollHandler);
            storm.events.remove(window, 'resize', storm.resizeHandler);
            if (storm.freezeOnBlur) {
              if (isIE) {
                storm.events.remove(document, 'focusout', .........完整代码请登录后点击上方下载按钮下载查看