奇妙的 clip-path 几何图形

CSS 新属性 clip-path，意味裁剪路径的意思，让我们可以很便捷的生成各种几何图形。

clip-path 通过定义特殊的路径，实现我们想要的图形。而这个路径，正是 SVG 中的 path 。

clip-path  属性api:

/* Keyword values */
clip-path: none;

/* Image values */ 
clip-path: url(resources.svg#c1);

/* Box values
clip-path: fill-box;
clip-path: stroke-box;
clip-path: view-box;
clip-path: margin-box
clip-path: border-box
clip-path: padding-box
clip-path: content-box

/* Geometry values */
/*矩形可以2个值， 也可 4个值    top right bottom left
   矩形可以3个值  第一个值 大小 第二值圆角属性【round】  第三个值圆角大小
*/
clip-path: inset(100px 50px);  
 /*圆形  第一个值大小  第二值 左右水平位置  第三个上下垂直 位置*/
clip-path: circle(50px at 0 100px);   /* */
clip-path: polygon(50% 0%, 100% 50%, 50% 100%, 0% 50%);

/* Box and geometry values combined */
clip-path: padding-box circle(50px at 0 100px);

/* Global values */
clip-path: inherit;
clip-path: initial;
clip-path: unset;

例如 clip-path: circle(50px at 50px 50px) 表示在元素的 （50px, 50px）处，裁剪生成一个半径为 50px 的圆，以元素的左上角为坐标起点

而整个 clip-path 属性，最为重要的当属 polygon，可以利用 polygon 生成任意多边形, polygon 几对【x,y】几边形，值可以 是百分比，也可以使用具体的数值。

下面分别列举使用 clip-path 生成一个圆形和一个十边形：

/* 圆形 */
.circle {
  width: 100px;
  height: 100px;
  background-color: yellowgreen; 
  clip-path: circle(50px at 50px 50px);
}

/* 十边形 */
.polygon {
  width: 100px;
  height: 100px;
  background-color: yellowgreen; 
  /*polygon(x1,y1,x2,y2...)*/
  clip-path: polygon(50% 0%, 80% 10%, 100% 35%, 100% 70%, 80% 90%, 50% 100%, 20% 90%, 0% 70%, 0% 35%, 20% 10%);
}

clip-path 动画

clip-path 另外一个强大之处在于可以进行 CSS transtion 与 CSS animation，也就是过渡和动画。

<div class="polygon-animate"></div> /* 几何图形变换 polygon 坐标位置可以去 http://bennettfeely.com/clippy/ 获取 如果页面打开过慢 或点击图像选择不了请 使用翻墙软件 */

 .polygon-animate {
  position: absolute;
  width: 200px;
  height: 200px;
  top: 50%;
  left: 50%;
  -webkit-transform: translate(-50%, -50%);
          transform: translate(-50%, -50%);
  background-color: crimson;
  -webkit-transition: .3s;
  transition: .3s;
  -webkit-clip-path: polygon(50% 0%, 0% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%);
          clip-path: polygon(50% 0%, 0% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%);
  -webkit-animation: polygon-ani 5s linear infinite;
          animation: polygon-ani 5s linear infinite;
}

@-webkit-keyframes polygon-ani {
  10% {
    background-color: darkorange;
    -webkit-clip-path: polygon(50% 0%, 100% 50%, 50% 100%, 0% 50%, 0% 50%, 0% 50%, 0% 50%, 0% 50%, 0% 50%);
            clip-path: polygon(50% 0%, 100% 50%, 50% 100%, 0% 50%, 0% 50%, 0% 50%, 0% 50%, 0% 50%, 0% 50%);
  }
  14% {
    -webkit-clip-path: polygon(50% 0%, 100% 50%, 50% 100%, 0% 50%, 0% 50%, 0% 50%, 0% 50%, 0% 50%, 0% 50%);
            clip-path: polygon(50% 0%, 100% 50%, 50% 100%, 0% 50%, 0% 50%, 0% 50%, 0% 50%, 0% 50%, 0% 50%);
  }
  24% {
    background-color: lemonchiffon;
    -webkit-clip-path: polygon(100% 38%, 82% 100%, 82% 100%, 18% 100%, 0% 38%, 0% 38%, 0% 38%, 0% 38%, 50% 0%);
            clip-path: polygon(100% 38%, 82% 100%, 82% 100%, 18% 100%, 0% 38%, 0% 38%, 0% 38%, 0% 38%, 50% 0%);
  }
  28% {
    -webkit-clip-path: polygon(100% 38%, 82% 100%, 82% 100%, 18% 100%, 0% 38%, 0% 38%, 0% 38%, 0% 38%, 50% 0%);
            clip-path: polygon(100% 38%, 82% 100%, 82% 100%, 18% 100%, 0% 38%, 0% 38%, 0% 38%, 0% 38%, 50% 0%);
  }
  38% {
    background-color: darkturquoise;
    -webkit-clip-path: polygon(50% 0%, 100% 25%, 100% 75%, 100% 75%, 50% 100%, 0% 75%, 0% 75%, 0% 25%, 0% 25%);
            clip-path: polygon(50% 0%, 100% 25%, 100% 75%, 100% 75%, 50% 100%, 0% 75%, 0% 75%, 0% 25%, 0% 25%);
  }
  42% {
    -webkit-clip-path: polygon(50% 0%, 100% 25%, 100% 75%, 100% 75%, 50% 100%, 0% 75%, 0% 75%, 0% 25%, 0% 25%);
            clip-path: polygon(50% 0%, 100% 25%, 100% 75%, 100% 75%, 50% 100%, 0% 75%, 0% 75%, 0% 25%, 0% 25%);
  }
  52% {
    background-color: darkcyan;
    -webkit-clip-path: polygon(50% 0%, 90% 20%, 100% 60%, 75% 100%, 25% 100%, 25% 100%, 0% 60%, 10% 20%, 50% 0%);
            clip-path: polygon(50% 0%, 90% 20%, 100% 60%, 75% 100%, 25% 100%, 25% 100%, 0% 60%, 10% 20%, 50% 0%);
  }
  56% {
    -webkit-clip-path: polygon(50% 0%, 90% 20%, 100% 60%, 75% 100%, 25% 100%, 25% 100%, 0% 60%, 10% 20%, 50% 0%);
            clip-path: polygon(50% 0%, 90% 20%, 100% 60%, 75% 100%, 25% 100%, 25% 100%, 0% 60%, 10% 20%, 50% 0%);
  }
  66% {
    background-color: deepskyblue;
    -webkit-clip-path: polygon(30% 0%, 70% 0%, 70% 0%, 100% 30%, 100% 70%, 70% 100%, 30% 100%, 0% 70%, 0% 30%);
            clip-path: polygon(30% 0%, 70% 0%, 70% 0%, 100% 30%, 100% 70%, 70% 100%, 30% 100%, 0% 70%, 0% 30%);
  }
  70% {
    -webkit-clip-path: polygon(30% 0%, 70% 0%, 70% 0%, 100% 30%, 100% 70%, 70% 100%, 30% 100%, 0% 70%, 0% 30%);
            clip-path: polygon(30% 0%, 70% 0%, 70% 0%, 100% 30%, 100% 70%, 70% 100%, 30% 100%, 0% 70%, 0% 30%);
  }
  80% {
    background-color: indigo;
    -webkit-clip-path: polygon(83% 12%, 100% 43%, 94% 78%, 68% 100%, 32% 100%, 6% 78%, 0% 43%, 17% 12%, 50% 0%);
            clip-path: polygon(83% 12%, 100% 43%, 94% 78%, 68% 100%, 32% 100%, 6% 78%, 0% 43%, 17% 12%, 50% 0%);
  }
  84% {
    -webkit-clip-path: polygon(83% 12%, 100% 43%, 94% 78%, 68% 100%, 32% 100%, 6% 78%, 0% 43%, 17% 12%, 50% 0%);
            clip-path: polygon(83% 12%, 100% 43%, 94% 78%, 68% 100%, 32% 100%, 6% 78%, 0% 43%, 17% 12%, 50% 0%);
  }
  94% {
    background-color: crimson;
    -webkit-clip-path: polygon(50% 0%, 0% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%);
            clip-path: polygon(50% 0%, 0% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%);
  }
}

@keyframes polygon-ani {
  10% {
    background-color: darkorange;
    -webkit-clip-path: polygon(50% 0%, 100% 50%, 50% 100%, 0% 50%, 0% 50%, 0% 50%, 0% 50%, 0% 50%, 0% 50%);
            clip-path: polygon(50% 0%, 100% 50%, 50% 100%, 0% 50%, 0% 50%, 0% 50%, 0% 50%, 0% 50%, 0% 50%);
  }
  14% {
    -webkit-clip-path: polygon(50% 0%, 100% 50%, 50% 100%, 0% 50%, 0% 50%, 0% 50%, 0% 50%, 0% 50%, 0% 50%);
            clip-path: polygon(50% 0%, 100% 50%, 50% 100%, 0% 50%, 0% 50%, 0% 50%, 0% 50%, 0% 50%, 0% 50%);
  }
  24% {
    background-color: lemonchiffon;
    -webkit-clip-path: polygon(100% 38%, 82% 100%, 82% 100%, 18% 100%, 0% 38%, 0% 38%, 0% 38%, 0% 38%, 50% 0%);
            clip-path: polygon(100% 38%, 82% 100%, 82% 100%, 18% 100%, 0% 38%, 0% 38%, 0% 38%, 0% 38%, 50% 0%);
  }
  28% {
    -webkit-clip-path: polygon(100% 38%, 82% 100%, 82% 100%, 18% 100%, 0% 38%, 0% 38%, 0% 38%, 0% 38%, 50% 0%);
            clip-path: polygon(100% 38%, 82% 100%, 82% 100%, 18% 100%, 0% 38%, 0% 38%, 0% 38%, 0% 38%, 50% 0%);
  }
  38% {
    background-color: darkturquoise;
    -webkit-clip-path: polygon(50% 0%, 100% 25%, 100% 75%, 100% 75%, 50% 100%, 0% 75%, 0% 75%, 0% 25%, 0% 25%);
            clip-path: polygon(50% 0%, 100% 25%, 100% 75%, 100% 75%, 50% 100%, 0% 75%, 0% 75%, 0% 25%, 0% 25%);
  }
  42% {
    -webkit-clip-path: polygon(50% 0%, 100% 25%, 100% 75%, 100% 75%, 50% 100%, 0% 75%, 0% 75%, 0% 25%, 0% 25%);
            clip-path: polygon(50% 0%, 100% 25%, 100% 75%, 100% 75%, 50% 100%, 0% 75%, 0% 75%, 0% 25%, 0% 25%);
  }
  52% {
    background-color: darkcyan;
    -webkit-clip-path: polygon(50% 0%, 90% 20%, 100% 60%, 75% 100%, 25% 100%, 25% 100%, 0% 60%, 10% 20%, 50% 0%);
            clip-path: polygon(50% 0%, 90% 20%, 100% 60%, 75% 100%, 25% 100%, 25% 100%, 0% 60%, 10% 20%, 50% 0%);
  }
  56% {
    -webkit-clip-path: polygon(50% 0%, 90% 20%, 100% 60%, 75% 100%, 25% 100%, 25% 100%, 0% 60%, 10% 20%, 50% 0%);
            clip-path: polygon(50% 0%, 90% 20%, 100% 60%, 75% 100%, 25% 100%, 25% 100%, 0% 60%, 10% 20%, 50% 0%);
  }
  66% {
    background-color: deepskyblue;
    -webkit-clip-path: polygon(30% 0%, 70% 0%, 70% 0%, 100% 30%, 100% 70%, 70% 100%, 30% 100%, 0% 70%, 0% 30%);
            clip-path: polygon(30% 0%, 70% 0%, 70% 0%, 100% 30%, 100% 70%, 70% 100%, 30% 100%, 0% 70%, 0% 30%);
  }
  70% {
    -webkit-clip-path: polygon(30% 0%, 70% 0%, 70% 0%, 100% 30%, 100% 70%, 70% 100%, 30% 100%, 0% 70%, 0% 30%);
            clip-path: polygon(30% 0%, 70% 0%, 70% 0%, 100% 30%, 100% 70%, 70% 100%, 30% 100%, 0% 70%, 0% 30%);
  }
  80% {
    background-color: indigo;
    -webkit-clip-path: polygon(83% 12%, 100% 43%, 94% 78%, 68% 100%, 32% 100%, 6% 78%, 0% 43%, 17% 12%, 50% 0%);
            clip-path: polygon(83% 12%, 100% 43%, 94% 78%, 68% 100%, 32% 100%, 6% 78%, 0% 43%, 17% 12%, 50% 0%);
  }
  84% {
    -webkit-clip-path: polygon(83% 12%, 100% 43%, 94% 78%, 68% 100%, 32% 100%, 6% 78%, 0% 43%, 17% 12%, 50% 0%);
            clip-path: polygon(83% 12%, 100% 43%, 94% 78%, 68% 100%, 32% 100%, 6% 78%, 0% 43%, 17% 12%, 50% 0%);
  }
  94% {
    background-color: crimson;
    -webkit-clip-path: polygon(50% 0%, 0% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%);
            clip-path: polygon(50% 0%, 0% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%, 100% 100%);
  }
}

除此之外，我们还可以尝试，将一个完整的图形，分割成多个小图形

<hgroup class="triangle2rect">
    <div class="a"></div>
    <div class="b"></div>
    <div class="c"></div>
    <div class="d"></div>
</hgroup>

.triangle2rect {
    position: absolute;
    width: 100px;
    height: 100px;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    animation: aniContainer 2s infinite alternate;
}
.triangle2rect div {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}
.a {
    background: deeppink;
    clip-path: polygon(0% 0%, 0% 100%, 50% 50%);
    animation: a 2s infinite alternate;
}
.b {
    background: deeppink;
    clip-path: polygon(0% 0%, 100% 0%, 50% 50%);
    animation: b 2s infinite alternate;
}
.c {
    background: deeppink;
    clip-path: polygon(100% 0%, 100% 100%, 50% 50%);
    animation: c 2s infinite alternate;
}
.d {
    background: deeppink;
    clip-path: polygon(100% 100%, 0% 100%, 50% 50%);
    animation: d 2s infinite alternate;
}
@keyframes a {
    0%, 10% {
        background: deeppink;
        clip-path: polygon(0% 0%, 0% 100%, 50% 50%);
    }
    90%, 100% {
        background: #000;
        clip-path: polygon(0% 100%, 25% 100%, 12.5% 0%);
    }
}
@keyframes b {
    0%, 10% {
        background: deeppink;
        clip-path: polygon(0% 0%, 100% 0%, 50% 50%);
    }
    90%, 100% {
        background: #000;
        clip-path: polygon(25% 0%, 50% 0%, 37.5% 100%);
    }
}
@keyframes c {
    0%, 10% {
        background: deeppink;
        clip-path: polygon(100% 0%, 100% 100%, 50% 50%);
    }
    90%, 100% {
        background: #000;
        clip-path: polygon(62.5% 0%, 75% 100%, 50% 100%);
    }
}
@keyframes d {
    0%, 10% {
        background: deeppink;
        clip-path: polygon(100% 100%, 0% 100%, 50% 50%);
    }
    90%, 100% {
        background: #000;
        clip-path: polygon(100% 0%, 87.5% 100%, 75% 0%);
    }
}
@keyframes aniContainer {
    0%, 10% {
        width: 100px;
        height: 100px;
    }
    90%, 100% {
        width: 250px;
        height: 60px;
    }
}

clip-path 动画的局限

clip-path 动画虽然美好，但是存在一定的局限性，那就是进行过渡的两个状态，坐标顶点的数量必须一致。

也就是如果我希望从三角形过渡到矩形。假设三角形和矩形的 clip-path 分别为：

• 三角形：clip-path: polygon(50% 0, 0 100%, 100% 0)
• 矩形： clip-path: polygon(0 0, 100% 0, 100% 100%, 0 100%)

进行过渡动画时候，直接从 polygon(50% 0, 0 100%, 100% 0) --> polygon(0 0, 100% 0, 100% 100%, 0 100%) 是不行的，因为是从 3 个坐标点变换到 4 个坐标点。

因此这里需要这用一个讨巧的办法，在三角形的表示方法中，使用四个坐标点表示，其中两个坐标点进行重合即可。也就是：

• 三角形：clip-path: polygon(50% 0, 0 100%, 100% 0) -> clip-path: polygon(50% 0, 50% 0, 0 100%, 100% 0)

N边形过渡动画

如果脑洞够大，随机生成 N（N>=1000）边形  //只是随机生成了 2000 个坐标点，然后使用 clip-path 将这些坐标点连接起来，并不是符合要求的多边形

https://codepen.io/Chokcoco/pen/XgJRzO?editors=1010

<div></div>

div {
    width: 300px;
    height: 300px;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    transition: all .5s;
    transition-timing-function: cubic-bezier(.92,-0.5,1,.12);
    border-radius: 50%;
}

setInterval(function() {
    const length = 2000;

    let el = document.querySelectorAll("div")[0];
    let coordinate = "";

    for (let i = 0; i < length; i++) {
        coordinate +=
            parseInt(Math.random() * 10000) / 100 +
            "% " +
            parseInt(Math.random() * 10000) / 100 +
            "%, ";
    }

    coordinate = "polygon(" + coordinate.slice(0, -2) + ")";

    el.style.clipPath = coordinate;
    el.style.backgroundColor =
        "#" + (~~(Math.random() * (1 << 24))).toString(16);
}, 500);

改良后的 (VUE官网)  https://codepen.io/Chokcoco/pen/NgqGOo?editors=1111

<div id="app">
    <!-- 使用 clip-path -->
    <div id="svgpolygon" v-bind:style="styleObject"></div>
    <label>Sides: {{ sides }}</label>
    <input type="range" min="3" max="500" v-model.number="sides">
    <label>Minimum Radius: {{ minRadius }}%</label>
    <input type="range" min="0" max="90" v-model.number="minRadius">
    <label>Update Interval: {{ updateInterval }} milliseconds</label>
    <input type="range" min="10" max="2000" v-model.number="updateInterval">
</div>

#svgpolygon {
    display: block;
    width: 180px;
    height: 180px;
    border-radius: 50%;
    border: 1px solid #333;
}

input[type="range"] {
  display: block;
  width: 100%;
  margin-bottom: 15px;
}

new Vue({
    el: "#app",
    data: function() {
        var defaultSides = 500;
        var stats = Array.apply(null, { length: defaultSides }).map(function() {
            return 100;
        });
        return {
            stats: stats,
            points: generatePoints(stats),
            sides: defaultSides,
            minRadius: 50,
            interval: null,
            updateInterval: 500
        };
    },
    computed: {
        styleObject: function() {
            return {
                background: '#41B883',
                'clip-path': 'polygon(' + this.points +')'
            }
        }
    },
    watch: {
        sides: function(newSides, oldSides) {
            var sidesDifference = newSides - oldSides;
            if (sidesDifference > 0) {
                for (var i = 1; i <= sidesDifference; i++) {
                    this.stats.push(this.newRandomValue());
                }
            } else {
                var absoluteSidesDifference = Math.abs(sidesDifference);
                for (var i = 1; i <= absoluteSidesDifference; i++) {
                    this.stats.shift();
                }
            }
        },
        stats: function(newStats) {
            TweenLite.to(this.$data, this.updateInterval / 1000, {
                points: generatePoints(newStats)
            });
        },
        updateInterval: function() {
            this.resetInterval();
        }
    },
    mounted: function() {
        this.resetInterval();
    },
    methods: {
        randomizeStats: function() {
            var vm = this;
            this.stats = this.stats.map(function() {
                return vm.newRandomValue();
            });
        },
        newRandomValue: function() {
            return Math.ceil(
                this.minRadius + Math.random() * (100 - this.minRadius)
            );
        },
        resetInterval: function() {
            var vm = this;
            clearInterval(this.interval);
            this.randomizeStats();
            this.interval = setInterval(function() {
                vm.randomizeStats();
            }, this.updateInterval);
        }
    }
});

function valueToPoint(value, index, total) {
    var x = 0;
    var y = -value * 0.9;
    var angle = Math.PI * 2 / total * index;
    var cos = Math.cos(angle);
    var sin = Math.sin(angle);
    var tx = x * cos - y * sin + 100;
    var ty = x * sin + y * cos + 100;
    return { x: tx, y: ty };
}

function generatePoints(stats) {
    var total = stats.length;
    var points = stats
        .map(function(stat, index) {
            var point = valueToPoint(stat, index, total);
            return point.x + "px " + point.y +"px,";
        })
        .join(" ");
    
    points = points.slice(0, -1);
     
    return points;
}