<svg version="1.1" id="Layer_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
	 width="800px" height="400px" viewBox="0 0 800 400" style="enable-background:new 0 0 800 400;" xml:space="preserve">
<style type="text/css">
	.st0{fill:#1D1D1D;stroke:#000000;stroke-miterlimit:10;}
	.st1{fill:#88C540;}
	.st2{fill:none;stroke:#E5285D;stroke-miterlimit:10;}
</style>
<rect id="background" class="st0" width="800" height="400"/>
<path id="square" class="st1" d="M525.667,321.333H274.333V78.667h251.333V321.333z"/>
<path id="star" class="st2" d="M400,82.531l38.168,77.336l85.346,12.401l-61.757,60.198l14.579,85.001L400,277.336l-76.336,40.132
	l14.579-85.001l-61.757-60.198l85.346-12.401L400,82.531z"/>
</svg>

svg {
  display: block;
  margin: 0 auto;
  overflow: visible;
}
body {
  background: #333;
  text-align:center;
  color:#ccc; 
  font-family:Asap, 'sans-serif';
}

button {
  padding:6px;
  font-size:22px;
}
.nav{
   margin:30px;
   font-size:18px;
}

/*
		For use with GreenSock's MorphSVGPlugin - helps find the best-looking shapeIndex value.

		USAGE:
		findShapeIndex("#yourTarget", "#otherShape", {duration:3, ease:"none", size:10});

		You can pass in either the other shape's selector text, or the full path data, like:

		findShapeIndex("#yourTarget", "M506.066,200L400,306.066L293.934,200L400,93.934L506.066,200z", {duration:3, ease:"none", size:10});

		Tap the up/down arrows (or left/right or "u"/"d") to change the shapeIndex.

		Requires: GSAP 3.0.0 (or later), MorphSVGPlugin

		LAST UPDATED: 2019-11-10
		Copyright 2019, GreenSock Inc.
		@author: Jack Doyle, jack@greensock.com
		*/

function findShapeIndex(target, endShape, vars) {
  vars = vars || {};
  var _doc = document,
      _get = function(e) {
        return _doc.querySelectorAll(e);
      },
      _createSVG = function(type, attributes) {
        var element = _doc.createElementNS("http://www.w3.org/2000/svg", type),
            reg = /([a-z])([A-Z])/g,
            p;
        for (p in attributes) {
          element.setAttributeNS(null, p.replace(reg, "$1-$2").toLowerCase(), attributes[p]);
        }
        return element;
      },
      _numExp = /[-+=\.]*\d+[\.e\-\+]*\d*[e\-\+]*\d*/gi, //finds any numbers, including ones that start with += or -=, negative numbers, and ones in scientific notation like 1e-8.
      _selectorExp = /(^[#\.][a-z]|[a-y][a-z])/gi,
      _parseShape = (shape, forcePath, target) => {
        let isString = typeof(shape) === "string",
            e, type;
        if (!isString || _selectorExp.test(shape) || (shape.match(_numExp) || []).length < 3) {
          e = gsap.utils.toArray(shape)[0];
          if (e) {
            type = (e.nodeName + "").toUpperCase();
            if (forcePath && type !== "PATH") { //if we were passed an element (or selector text for an element) that isn't a path, convert it.
              e = MorphSVGPlugin.convertToPath(e, false);
              type = "PATH";
            }
            shape = e.getAttribute(type === "PATH" ? "d" : "points") || "";
            if (e === target) { //if the shape matches the target element, the user wants to revert to the original which should have been stored in the data-original attribute
              shape = e.getAttributeNS(null, "data-original") || shape;
            }
          } else {
            console.warn("Invalid morph to: " + shape);
            shape = false;
          }
        }
        return shape;
      },
      startDot, endDot, incrementButton, decrementButton,
      _setup = function() {
        var e = _doc.createElement("div"),
            label = _doc.createElement("div"),
            body = _get("body")[0];
        incrementButton = _doc.createElement("div");
        decrementButton = _doc.createElement("div");
        label.setAttribute("id", "shapeIndexLabel");
        startDot = _createSVG("circle", {cx:0, cy:0, r:(vars.startStrokeWidth || 3) + 3, fill:vars.startStroke || "red"});
        endDot = _createSVG("circle", {cx:0, cy:0, r:(vars.endStrokeWidth || 3) + 3, fill:vars.endStroke || "yellow"});
        gsap.set(e, {padding:"0px", position:"absolute", bottom:0, fontSize:"20px", textAlign:"center", backgroundColor: "black", color:"#91e600", border:"1px solid #999", left:"50%", xPercent:-50, yPercent:-50, userSelect:"none", fontFamily:"sans-serif", zIndex: 100});
        gsap.set(label, {display:"inline-block", minWidth:"210px", marginRight:"10px", textAlign:"center", marginLeft:"10px"});
        gsap.set([incrementButton, decrementButton], {display:"inline-block", padding:"0 15px", color:"#ccc", height:"50px", lineHeight:"48px", cursor:"pointer"});
        gsap.set(decrementButton, {borderRight:"1px solid #999"});
        gsap.set(incrementButton, {borderLeft:"1px solid #999"});
        decrementButton.innerHTML = " - ";
        incrementButton.innerHTML = " + ";
        e.appendChild(decrementButton);
        e.appendChild(label);
        e.appendChild(incrementButton);
        if (body) {
          body.appendChild(e);
        }
        return label;
      },
      label = _get("#shapeIndexLabel")[0] || _setup(),
      index = 0,
      _yoyo = function() {
        shapeTween.reversed(!shapeTween.reversed()).resume();
        dotTween.reversed(!dotTween.reversed()).resume();
      },
      shapeTween,	dotTween, startBezier, endBezier,
      dotProxy = {x:0, y:0},
      _getFirstCoordinates = function(start, end, shapeIndex) {
        startBezier = MorphSVGPlugin.stringToRawPath(start);
        endBezier = MorphSVGPlugin.stringToRawPath(end);

        MorphSVGPlugin.equalizeSegmentQuantity(startBezier, endBezier, shapeIndex);
        return [startBezier[0][0], startBezier[0][1], endBezier[0][0], endBezier[0][1]];
      },
      _startTween = function() {
        var coordinates = _getFirstCoordinates(origStartShape, origEndShape, index);
        dotProxy.x = coordinates[0];
        dotProxy.y = coordinates[1];
        startDot.setAttribute("cx", dotProxy.x);
        startDot.setAttribute("cy", dotProxy.y);
        endDot.setAttribute("cx", coordinates[2]);
        endDot.setAttribute("cy", coordinates[3]);
        shapeTween = gsap.fromTo(target, {morphSVG: origStartShape}, {delay:0.5, duration:vars.duration || 3, morphSVG:{shape:origEndShape, shapeIndex:index}, ease:vars.ease || "none", onComplete:_yoyo, onReverseComplete:_yoyo, overwrite:true});
        dotTween = gsap.to(dotProxy, {delay:0.5, duration:vars.duration || 3, x:coordinates[2], y:coordinates[3], ease:vars.ease || "none", onUpdate:function() {
          startDot.setAttribute("cx", dotProxy.x);
          startDot.setAttribute("cy", dotProxy.y);
        }});
      },
      _refresh = function() {
        label.innerHTML = "shapeIndex: " +  index + (index === autoIndex ? " (auto)" : "");
        shapeTween.seek(0).kill();
        dotTween.seek(0).kill();
        _startTween();
        gsap.fromTo(label.parentNode, 0.4, {backgroundColor:"#777"}, {backgroundColor:"black", ease:"none"});
      },
      _increment = function() {
        index = (index + 1) % (maxIndex + 1);
        _refresh();
      },
      _decrement = function() {
        index = (index - 1) % (maxIndex + 1);
        _refresh();
      },
      autoIndex,	maxIndex, endTarget;
  if (typeof(target) === "string") {
    target = gsap.utils.toArray(target)[0];
  }
  if (!target) {
    console.log("ERROR: target not found for findShapeIndex(). Please use a valid target.");
    return;
  } else if (target.nodeName && target.nodeName.toUpperCase() !== "PATH") {
    console.log("ERROR: target of findShapeIndex() must be a path.");
    return;
  } else if (target.push && target[0] && target[0].nodeName) {
    target = target[0];
  }
  if (target.parentNode) {
    target.parentNode.appendChild(endDot);
    target.parentNode.appendChild(startDot);
  }
  if (typeof(endShape) !== "string" || (endShape.match(_numExp) || []).length < 3) {
    endTarget = gsap.utils.toArray(endShape);
    if (endTarget && endTarget[0]) {
      endTarget = endTarget[0];
      gsap.set(endTarget, {display:"block", strokeWidth:vars.endStrokeWidth || 3, stroke:vars.endStroke || "yellow", fill:vars.endFill || "none", visibility:"visible", opacity:vars.endOpacity || 0.7});
    }
  }
  gsap.set(target, {display:"block", strokeWidth:vars.startStrokeWidth || 3, stroke:vars.startStroke || "red", fill:vars.startFill || "none", visibility:"visible", opacity:vars.startOpacity || 0.7});
  startBezier = MorphSVGPlugin.stringToRawPath(target.getAttribute("d"));
  endBezier = MorphSVGPlugin.stringToRawPath(_parseShape(endShape, true));
  autoIndex = index = Math.round(MorphSVGPlugin.equalizeSegmentQuantity(startBezier, endBezier, "auto")[0]); //also handles subdividing!
  maxIndex = (startBezier[0].length / 6) | 0;
  gsap.killTweensOf([target, endShape]); //kill other tweens so they don't interfere with our yoyo-ing one.

  const origStartShape = _parseShape(target, true);
  const origEndShape = _parseShape(endShape, true);
  _startTween();
  label.innerHTML = "shapeIndex: " +  index + (index === autoIndex ? " (auto)" : "");
  window.addEventListener("keydown", function(event) {
    var key = event.keyCode;
    if (key === 38 || key === 39 || key === 85) { //right or up arrows (increment)
      _increment();
    } else if (key === 37 || key === 40 || key === 68) { //left or down arrows (decrement)
      _decrement();
    }
  });
  incrementButton.addEventListener("click", _increment);
  decrementButton.addEventListener("click", _decrement);
}

gsap.to("#square", {duration: 3, morphSVG:{shape:"#star", shapeIndex:5}});
//comment out next line to disable findShapeIndex() UI
findShapeIndex("#square", "#star");

External CSS

  1. https://codepen.io/GreenSock/pen/ee8ac247ddeb87e229d660127c6fe73d

External JavaScript

  1. https://s3-us-west-2.amazonaws.com/s.cdpn.io/16327/gsap-latest-beta.min.js?r=2314
  2. https://s3-us-west-2.amazonaws.com/s.cdpn.io/16327/MorphSVGPlugin3.min.js