• svg-star


    <!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Document</title>
        <style>
            html { text-align: center; }
    
            body { background: #000; color: #fff; }
    
            svg {  3vmin;}
    
            path { cursor: pointer }
    
            h1, p { font: 2em trebuchet ms, verdana, sans-serif; }
    
            p { font-size: 1em; }
    
            a { color: greenyellow; }
        </style>
    </head>
    <body>
        <p><a href='https://codepen.io/thebabydino/pen/RWvaZW' target='_blank'>hello world</a></p>
    <svg>
      <path id='shape'/>
    </svg>
    <script>
        const _SVG = document.querySelector('svg'), 
                _SHAPE = document.getElementById('shape'), 
                D = 1000 /* viewBox size */,
                O = {} /* data object */,
                /* number of cubic curves/ polygon vertices */
                P = 5, 
                NF = 50 /* total number of frames for transition */, 
                TFN = { /* timing functions */
            'ease-out': function(k) {
              return 1 - Math.pow(1 - k, 1.675)
            }, 
            'ease-in-out': function(k) {
              return .5*(Math.sin((k - .5)*Math.PI) + 1)
            },
            'bounce-ini-fin': function(k, s = -.65*Math.PI, e = -s) {
              return (Math.sin(k*(e - s) + s) - Math.sin(s))/(Math.sin(e) - Math.sin(s))
            }
          };
    
    let dir = -1, rID = null, cf = 0, m;
    
    function getStarPoints(f = .5) {
        const RCO = f*D /* outer (pentagram) circumradius*/, 
                    BAS = 2*(2*Math.PI/P) /* base angle for star poly */, 
                    BAC = 2*Math.PI/P /* base angle for convex poly */, 
                    RI = RCO*Math.cos(.5*BAS) /*pentagram/ inner pentagon inradius */, 
                    RCI = RI/Math.cos(.5*BAC) /* inner pentagon circumradius */, 
                    ND = 2*P /* total number of distinct points we need to get */, 
                    BAD = 2*Math.PI/ND /* base angle for point distribution */, 
                    PTS = [] /* array we fill with point coordinates */;
    
        for(let i = 0; i < ND; i++) {
            let /* radius at end point (inner)/ control point (outer) */
                    cr = i%2 ? RCI : RCO, 
                    /* angle of radial segment from origin to current point */
                    ca = i*BAD + .5*Math.PI, 
                    x = Math.round(cr*Math.cos(ca)), 
                    y = Math.round(cr*Math.sin(ca));
    
            PTS.push([x, y]);
            /* for even indices double it, control points coincide here */
            if(!(i%2)) PTS.push([x, y]);
        }
    
        return PTS
    };
    
    function getHeartPoints(f = .25) {
        const R = f*D /* helper circle radius  */, 
        RC = Math.round(R/Math.SQRT2) /* circumradius of square of edge R */, 
        XT = 0, YT = -RC /* coords of point T */, 
        XA = 2*RC, YA = -RC /* coords of A points (x in abs value) */, 
        XB = 2*RC, YB = RC /* coords of B points (x in abs value) */, 
        XC = 0, YC = 3*RC /* coords of point C */, 
        XD = RC, YD = -2*RC /* coords of D points (x in abs value) */, 
        XE = 3*RC, YE = 0 /* coords of E points (x in abs value) */, 
        /* const for cubic curve approx of quarter circle */
        C = .551915, 
        CC = 1 - C, 
        /* coords of ctrl points on TD segs */
        XTD = Math.round(CC*XT + C*XD), YTD = Math.round(CC*YT + C*YD), 
            /* coords of ctrl points on AD segs */
            XAD = Math.round(CC*XA + C*XD), YAD = Math.round(CC*YA + C*YD), 
            /* coords of ctrl points on AE segs */
            XAE = Math.round(CC*XA + C*XE), YAE = Math.round(CC*YA + C*YE), 
            /* coords of ctrl points on BE segs */
            XBE = Math.round(CC*XB + C*XE), YBE = Math.round(CC*YB + C*YE);
        
        return [
            [XC, YC], [XC, YC], [-XB, YB], 
            [-XBE, YBE], [-XAE, YAE], [-XA, YA], 
            [-XAD, YAD], [-XTD, YTD], [XT, YT], 
            [XTD, YTD], [XAD, YAD], [XA, YA], 
            [XAE, YAE], [XBE, YBE], [XB, YB]
        ].map(([x, y]) => [x, y - .09*R]);
    };
    
    function fnStr(fname, farg) { return `${fname}(${farg})` };
    
    function range(ini, fin) {
        return (typeof ini == 'number') ? 
                        fin - ini : 
                        ini.map((c, i) => range(ini[i], fin[i]))
    };
    
    function int(ini, rng, tfn, k, cnt) {
        return (typeof ini == 'number') ? 
                        Math.round(ini + cnt*(m + dir*tfn(m + dir*k))*rng) : 
                        ini.map((c, i) => int(ini[i], rng[i], tfn, k, cnt))
    };
    
    function stopAni() {
      cancelAnimationFrame(rID);
      rID = null;  
    };
    
    function update() {
      cf += dir;
        
      let k = cf/NF;
        
        for(let p in O) {
            let c = O[p];
            
            _SHAPE.setAttribute(...[
                p, 
                c.afn(int(c.ini, c.rng, TFN[c.tfn], k, c.cnt ? dir : 1))
            ]);
        }
      
      if(!(cf%NF)) {
        stopAni();
        return
      }
      
      rID = requestAnimationFrame(update)
    };
    
    (function init() {  
        _SVG.setAttribute('viewBox', [-.5*D, -.5*D, D, D].join(' '));
        
        O.d = {
            ini: getStarPoints(), 
            fin: getHeartPoints(), 
            afn: function(pts) {
                return pts.reduce((a, c, i) => {
                    return a + (i%3 ? ' ' : 'C') + c
                }, `M${pts[pts.length - 1]}`)
            },
            tfn: 'ease-in-out'
        };
        
        O.transform = {
            ini: -180, 
            fin: 0, 
            afn: (ang) => fnStr('rotate', ang),
            tfn: 'bounce-ini-fin',
            cnt: 1
        };
        
        O.fill = {
            ini: [255, 215, 0], 
            fin: [220, 20, 60], 
            afn: (rgb) => fnStr('rgb', rgb),
            tfn: 'ease-out'
        };
        
        for(let p in O) {
            O[p].rng = range(O[p].ini, O[p].fin);
            _SHAPE.setAttribute(p, O[p].afn(O[p].ini));
        }
        
        _SHAPE.addEventListener('click', e => {
            if(rID) stopAni();
            dir *= -1;
            m = .5*(1 - dir);
            update();
        }, false);
    })();
    </script>
    </body>
    </html>
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  • 原文地址:https://www.cnblogs.com/SharkChilli/p/8477068.html
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