Implementing SVG Shape Morphing Animations on a Website
SVG morphing is animation of transforming one vector shape into another. Technically this is animation of the d attribute (path data) — numeric coordinates of points. Limitation: start and end shapes must have the same number of points and commands in path. That's why native SMIL and CSS are poorly suited for arbitrary morphing — specialized libraries are needed that interpolate points.
Tools
- GSAP MorphSVGPlugin — paid, part of Club GreenSock. Most powerful, aligns point count automatically
- Flubber.js — MIT, good for simple shapes
- SVG.js + @svgdotjs/svg.filter.js — via built-in morphing
- CSS/SMIL with same point count — for simple cases without libraries
GSAP MorphSVGPlugin (Most Reliable Approach)
// lib/gsap-morph.ts
import { gsap } from 'gsap'
import { MorphSVGPlugin } from 'gsap/MorphSVGPlugin'
gsap.registerPlugin(MorphSVGPlugin)
export { gsap }
// components/MorphingIcon.tsx
import { useEffect, useRef, useState } from 'react'
import { gsap } from '../lib/gsap-morph'
const shapes = {
circle: 'M 50,10 A 40,40 0 1,1 49.9,10',
star: 'M50,5 L61,35 L95,35 L68,57 L79,91 L50,70 L21,91 L32,57 L5,35 L39,35 Z',
heart: 'M50,85 C10,60 5,30 25,15 C35,7 45,10 50,18 C55,10 65,7 75,15 C95,30 90,60 50,85 Z',
arrow: 'M 10,50 L 40,20 L 40,35 L 90,35 L 90,65 L 40,65 L 40,80 Z',
}
type ShapeKey = keyof typeof shapes
export function MorphingIcon() {
const pathRef = useRef<SVGPathElement>(null)
const [current, setCurrent] = useState<ShapeKey>('circle')
const morphTo = (target: ShapeKey) => {
if (!pathRef.current || target === current) return
gsap.to(pathRef.current, {
morphSVG: {
shape: shapes[target],
// Anchor point for alignment (0–1, rotation in degrees)
origin: '50% 50%',
// Alignment type: position or matching degree
type: 'rotational',
},
duration: 0.8,
ease: 'power2.inOut',
})
setCurrent(target)
}
return (
<div>
<svg viewBox="0 0 100 100" className="w-32 h-32">
<path
ref={pathRef}
d={shapes.circle}
fill="none"
stroke="#3b82f6"
strokeWidth="2"
/>
</svg>
<div className="flex gap-2 mt-4">
{(Object.keys(shapes) as ShapeKey[]).map(key => (
<button
key={key}
onClick={() => morphTo(key)}
className={`px-3 py-1 text-sm rounded ${
current === key ? 'bg-blue-500 text-white' : 'bg-gray-100'
}`}
>
{key}
</button>
))}
</div>
</div>
)
}
Flubber.js: Free Alternative
npm install flubber
// components/FlubberMorph.tsx
import { useEffect, useRef, useState } from 'react'
import { interpolate, fromCircle, toCircle } from 'flubber'
// Flubber returns interpolator function: t(0) = start, t(1) = end
export function FlubberMorph() {
const pathRef = useRef<SVGPathElement>(null)
const animFrameRef = useRef<number | null>(null)
const morphBetween = (
startPath: string,
endPath: string,
durationMs = 800
) => {
const interpolator = interpolate(startPath, endPath, { maxSegmentLength: 2 })
const start = performance.now()
const animate = (now: number) => {
const elapsed = now - start
const t = Math.min(elapsed / durationMs, 1)
const ease = t < 0.5 ? 2 * t * t : -1 + (4 - 2 * t) * t // easeInOut
if (pathRef.current) {
pathRef.current.setAttribute('d', interpolator(ease))
}
if (t < 1) {
animFrameRef.current = requestAnimationFrame(animate)
}
}
if (animFrameRef.current) cancelAnimationFrame(animFrameRef.current)
animFrameRef.current = requestAnimationFrame(animate)
}
const squarePath =
'M 20,20 L 80,20 L 80,80 L 20,80 Z'
const blobPath =
'M 50,10 C 80,10 90,30 90,50 C 90,70 70,90 50,90 C 30,90 10,70 10,50 C 10,30 20,10 50,10 Z'
const [isBlob, setIsBlob] = useState(false)
useEffect(() => {
if (pathRef.current) {
pathRef.current.setAttribute('d', squarePath)
}
}, [])
const toggle = () => {
morphBetween(
isBlob ? blobPath : squarePath,
isBlob ? squarePath : blobPath
)
setIsBlob(!isBlob)
}
return (
<div>
<svg viewBox="0 0 100 100" className="w-48 h-48">
<path ref={pathRef} fill="#8b5cf6" />
</svg>
<button onClick={toggle} className="mt-4 px-4 py-2 bg-purple-500 text-white rounded">
Morph
</button>
</div>
)
}
SMIL Morphing without Libraries (Same Contours)
When both shapes have the same number of points — SMIL works without additional tools:
// Square → diamond → square (4 points, one command L)
export function SMILMorph() {
return (
<svg viewBox="0 0 100 100" className="w-32 h-32">
<path fill="#f59e0b">
<animate
attributeName="d"
dur="1.5s"
repeatCount="indefinite"
values="
M 20,20 L 80,20 L 80,80 L 20,80 Z;
M 50,10 L 90,50 L 50,90 L 10,50 Z;
M 20,20 L 80,20 L 80,80 L 20,80 Z
"
keyTimes="0; 0.5; 1"
calcMode="spline"
keySplines="0.4 0 0.2 1; 0.4 0 0.2 1"
/>
</path>
</svg>
)
}
Morphing with Multiple Target Shapes (GSAP Timeline)
// components/MorphSequence.tsx
import { useEffect, useRef } from 'react'
import { gsap } from '../lib/gsap-morph'
const sequence = [
'M 50,10 A 40,40 0 1,1 49.9,10', // circle
'M50,5 L61,35 L95,35 L68,57 L79,91 L50,70 Z', // star
'M10,50 L50,10 L90,50 L50,90 Z', // diamond
]
export function MorphSequence() {
const pathRef = useRef<SVGPathElement>(null)
useEffect(() => {
const tl = gsap.timeline({ repeat: -1, yoyo: false })
sequence.forEach((shape, i) => {
const next = sequence[(i + 1) % sequence.length]
tl.to(pathRef.current, {
morphSVG: next,
duration: 1.2,
ease: 'power1.inOut',
}, `+=${i === 0 ? 0 : 0.5}`) // pause between morphs
})
return () => { tl.kill() }
}, [])
return (
<svg viewBox="0 0 100 100" className="w-40 h-40">
<path
ref={pathRef}
d={sequence[0]}
fill="none"
stroke="#3b82f6"
strokeWidth="2"
strokeLinejoin="round"
/>
</svg>
)
}
Path Preparation: Tools
For morphing, shapes must be optimized:
- SVGO — path minimization and normalization
- Inkscape → "Modifications > Path > Add Nodes" — point count alignment
-
GSAP MorphSVGPlugin.convertToPath() — converts
<circle>,<rect>etc. to<path>
import { MorphSVGPlugin } from 'gsap/MorphSVGPlugin'
// Convert all primitives before registering morphing
MorphSVGPlugin.convertToPath('#my-circle, #my-rect')
Typical Timeline
Simple two-state morphing via SMIL — 4 hours. Interactive morphing with shape selection via GSAP — 1–2 working days. Complex animated illustration with sequences, color transitions and interactivity — 4–6 days.